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Dt-01/06/2015Comparisons of mechanical and metallurgical
properties of GMAW,
FCAW & MCAW weldments of SA516 GR70 steel Material
Pandit Deendayal Petroleum UniversitySchool of Technology
,Mechanical Engineering
Sponsored project of Department ofScience and Technology, New
Delhi
1
SupervisorDr. Vishvesh J Badheka, IWEAssociate Professor,
Mechanical Engineering DeptSchool of Technology,Pandit Deendayal
Petroleum University.
Review Presentation (4th Sem)
Presented ByPritesh J. PrajapatiRo.No- 13RME011PhD Student,
PDPU
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Content of Presentation
PhD journey Introduction.
GMAW FCAW MCAW
Gap Analyses. Research Plan Proposed Objectives Material
Selection. Experimental Procedure. Acknowledgement.
PhD journey Introduction.
GMAW FCAW MCAW
Gap Analyses. Research Plan Proposed Objectives Material
Selection. Experimental Procedure. Acknowledgement.
2
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SEM WORK DONE DURATION REMARKSem -I Course work
1).Fundamentals of Welding (ME-704)2).Advanced welding processes
(ME-701)3).Research Methodology (PET-701)
July-Dec2013
Good
Sem -II Compressive exam and Review ofLiterature survey
Jan-June2013
Good
PhD Journey Enrolled in July 2013
3
Sem -II Compressive exam and Review ofLiterature survey
Jan-June2013
Good
Sem -III Experiment-I July-Dec2014
Very good
Sem -IV Experiment-II Jan-June2015
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4
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IntroductionGMAW is an electric arc welding process
Fig.1
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6Fig.2
FCAW, has a hollow wire with flux in the center, Just as the
name states, a FluxCore.
The main difference between MIG welding and FCAW is, FCAW gets
its shieldingfrom the flux core, so use at weld outdoors. MIG
welding is the way the electrode isshielded from the air.
-
7The internal components of a metal cored wire are composed
chiefly of the alloys,manganese, silicon, and in some cases,
nickel. chromium and molybdenum as well as verysmall amounts of arc
stabilizers such as sodium and potassium, with the balance being
ironpowder.
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Gap Analyses Existing literature available in the area of the
GMAW and FCAW. Most of research
papers published are the comparison of the solid wire with flux
cored wire.
Metal cored wires are the latest development in the area of
advances consumables.There is general comparison of characteristics
of wires (solid, flux cored and metalcored) are available but
effect of different wire on mechanical and metallurgical isnot
reported.
Conventionally root run are being filled with the GTAW process
because it hasexcellent weld metal properties and subsequently
passes with GMAW or SAWdepending on the size of the job.
In addition to the above mentioned detail there is very little
research has beencarried out in the area of application of hybrid
welds using GMAW, FCAW &MCAW process.
Mechanical and metallurgical properties of solid, flux cored
wires ,metal coredwires are also will be compared with hybrid
welds.
Existing literature available in the area of the GMAW and FCAW.
Most of researchpapers published are the comparison of the solid
wire with flux cored wire.
Metal cored wires are the latest development in the area of
advances consumables.There is general comparison of characteristics
of wires (solid, flux cored and metalcored) are available but
effect of different wire on mechanical and metallurgical isnot
reported.
Conventionally root run are being filled with the GTAW process
because it hasexcellent weld metal properties and subsequently
passes with GMAW or SAWdepending on the size of the job.
In addition to the above mentioned detail there is very little
research has beencarried out in the area of application of hybrid
welds using GMAW, FCAW &MCAW process.
Mechanical and metallurgical properties of solid, flux cored
wires ,metal coredwires are also will be compared with hybrid
welds.
8
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Hybrid Welds
Hybrid welds in which root and filler pass filled with different
process.
Hybrid Welding Process
9
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Parameters Filler Wire diameter = 1.2mm. Welding Current - 200
A,Voltage - 28 V, Travel Speed 200
Shielding Gas Composition Ar/CO2 =90/10
I II III
ROOT SIDE GMAW FCAW MCAW
FILLER PASSES (OP-1) GMAW FCAW MCAW
Research Plan
FILLER PASSES (OP-1) GMAW FCAW MCAW
FILLER PASSES (OP-2) FCAW GMAW GMAW
FILLER PASSES (OP-3) MCAW MCAW FCAW
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SAMPLE ID ROOT RUN FILLER RUN
A GMAW GMAW
B GMAW FCAW
C GMAW MCAW
D FCAW GMAW
E FCAW FCAW
11
E FCAW FCAW
F FCAW MCAW
G MCAW GMAW
H MCAW FCAW
I MCAW MCAW
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Root passes andfiller pass filled withsolid wire flux coredand
metal cord wire.
Root passes filled withmetal cord wire and fillerpass with solid
wire.
Root passes -solid wire.filler pass with metal cordor flux cored
wire.
Fig.3
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Proposed Objectives
Experiments are made to in single V (60) groove joint design for
10mm thickSA516 Gr70 carbon steel plate using Solid wire (ER70S6),
flux cored wire (E71T-1C), and Metal Cored wire (E70C-6M) of 1.2 mm
in diameter.
Establishment of Welding Parameters for welding SA516 Gr70
Carbon steel plateusing GMAW ,FCAW and MCAW process.
Destructive and Non-destructive testing and characterization of
the welded joint asper applicable standards is carried out.
Comparison of Metallurgical & Mechanical properties of GMAW,
FCAW &MCAW welded Joints.
Experiments are made to in single V (60) groove joint design for
10mm thickSA516 Gr70 carbon steel plate using Solid wire (ER70S6),
flux cored wire (E71T-1C), and Metal Cored wire (E70C-6M) of 1.2 mm
in diameter.
Establishment of Welding Parameters for welding SA516 Gr70
Carbon steel plateusing GMAW ,FCAW and MCAW process.
Destructive and Non-destructive testing and characterization of
the welded joint asper applicable standards is carried out.
Comparison of Metallurgical & Mechanical properties of GMAW,
FCAW &MCAW welded Joints.
13
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Material Selection
SA516Gr70 carbon steel materials are widely used in heavy
fabrication applicationin which cost saving factor and high
strength are most important.
SA516 Grade 70 offers greater tensile and yield strength when
compared to ASTMSA516 Grade 65 and can operate in even lower
temperature service.
Table 1. Mechanical properties of consumables
Mechanical PropertiesSolid Wire
(ER70S-6)Flux Cored Wire
(E71T-1C)
Metal CoredWire
(E70C-6M)
Base metal
(SA516Gr70)
SA516Gr70 carbon steel materials are widely used in heavy
fabrication applicationin which cost saving factor and high
strength are most important.
SA516 Grade 70 offers greater tensile and yield strength when
compared to ASTMSA516 Grade 65 and can operate in even lower
temperature service.
Table 1. Mechanical properties of consumables
14
Solid Wire
(ER70S-6)Flux Cored Wire
(E71T-1C)
Metal CoredWire
(E70C-6M)
Yield Strength 427 MPa 605 MPa 448 MPa 446.9 MPa
Tensile Strength 529 MPa 579 MPa 549 MPa 590.60 MPa
Elongation 26% 31 % 31 % 24.8 %
CVN Impact Value
(Temp. C)35 J (30C)
80J (-20C) 103J(-30 C)
48J (-29C) 62J(-18C)
---
Shielding Gas --- 100% CO275% Ar-25%
CO2
---
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Contents Solid Wire
(ER70S-6)Flux cored
wire
(E71T-1C)
Metal cored wire
(E70C-6M)Base metal
(SA516Gr70)
C 0.07 0.03 0.048 0.186
Si 0.86 0.56 0.582 0.322
Mn 1.44 1.29 1.375 1.112
0.014
Table 2. Chemical composition of the filler wire and SA516 Gr70
carbon steel material.
P 0.014 0.011 0.014 0.014
S 0.008 0.005 0.012 0.009
Cr 0.025 0.04 0.023 0.030
Ni 0.014 0.02 0.014 0.026
Mo 0.002 0.01 0.001 0.019
V 0.002 0.02 0.004 0.001
Nb N/A N/A 0.002 Nil
Cu 0.15 0.01 0.015 0.033
15
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Experiment Procedure.
16
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Power Source Equipment
Photograph of Experimental Setup
Ar/CO2Gas Mixer
Power Source Equipment
WeldingTorch
SPMHead
StandardGas
Cylinders
FumeExtractor
Data Monitoring System
Above setup available at PDPU( Research work carried out under
sponsored project ofDepartment of Science and Technology (DST), New
Delhi)
Fig.4
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Experimental Condition
Base metal : SA516Grade70 Size : 30010010 mm Joint Design : V-
groove (60 angle, Root Gap= 04 mm) Wire Type : 1.2 mm Solid
(ER70S6), Flux cored (E71T-1C/M), MetalCored(E70C-6M) Welding
Variable:
a) Normal Fe modeb) Welding Current -200 Ac) Welding Voltage 28
Vd) Travel Speed 200mm/mine) Nozzle to Plate Distance -15 mmf)
Electrode Extension -8 to 10 mmg) Shielding Gas -90%Ar + 10%
CO2
Base metal : SA516Grade70 Size : 30010010 mm Joint Design : V-
groove (60 angle, Root Gap= 04 mm) Wire Type : 1.2 mm Solid
(ER70S6), Flux cored (E71T-1C/M), MetalCored(E70C-6M) Welding
Variable:
a) Normal Fe modeb) Welding Current -200 Ac) Welding Voltage 28
Vd) Travel Speed 200mm/mine) Nozzle to Plate Distance -15 mmf)
Electrode Extension -8 to 10 mmg) Shielding Gas -90%Ar + 10%
CO2
18
Fig.5 Joint Design
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Fig.6.Photographs of welded plates
FMFSFF
19
Carbon steel plate SA516Gr70 welded using FF shows that both
root pass and fillerpass filled with flux cored wire.
FS indicate Hybrid welds in which root pass filled with flux
cored wire and fillerpass with solid wire.
FM indicate Hybrid shows that root pass filled with flux cored
wire and filler passwith metal cored wired.
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Table 3. Full plate Experimental Data
ID Current in Amp Voltage in VoltWeldingspeed inmm/min
Heat input KJ/mm
Set 1 (*) 2 (*) ActualAvg.(*) Set 1 (*) 2 (*)ActualAvg.(*) Set
Cal. Cal.1 (*) Cal.2 (*)
ActualAvg.(*)
FF 200 273 282 277.5 28 27.9 28 27.95 200 1.68 2.28 2.36
2.32
FS 200 234 272 253.0 28 27.9 28.1 28.00 200 1.68 1.95 2.29
2.12
FM 200 228 271 249.5 28 27.9 28 27.95 200 1.68 1.90 2.27
2.09
20
1: First Trial 2: Second Trial .ctual (*): Values recorded by
online data monitoring system (During Welding).
KJ/mm Where, V- Voltage,I- Current,S- Welding Speed-Welding
Efficiency 0.9
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Angular Distortion
Dial Indicator
21 Angular distortion measurement were carried as per the
following procedure.
Fig.7 Schematic diagram of angular distortion measurements
[30]
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Weldingprocess
VerticalDisplacement Z in mm
HorizontalDisplacement
X in mm
Root runTemp.
Filler runTemp.
Avg. PeckTemperature
FF 4.66 100 2.68 420 394 407.0 Co
FS 4.98 100 2.66367 411 389Co
FM 3.94 100 1.72287 358 322.5 Co
Table 4. Angular Distortion and peck temperature Data
Contact typethermocouple
(K-Type- Nibase,chromel & alumel)
22Fig.(8) Calculated Angular Distortions
Contact typethermocouple
(K-Type- Nibase,chromel & alumel)
012345
FF FS FM
% Ang
u Dist
Consumables
Average pick temperature with flux coredwire is higher compare
to other welds, becauseof high input recorded using flux cored
wire, asshown in table 4That may be the reason for higher
angulardistortion in FF and lowest in FM.
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Macro preparation
The test specimen were cut from the welded plate after removing
run on and runoff.
Each metallographic specimens were prepared by:- Mechanical
grinding.- Polishing (120 and 320 grit silicon carbide),- Etching
(solution of 35% concentrated HCL (60%) and 35%
concentrated HNO3 (40%) for 2-3 min to produce a bright
surface.
The test specimen were cut from the welded plate after removing
run on and runoff.
Each metallographic specimens were prepared by:- Mechanical
grinding.- Polishing (120 and 320 grit silicon carbide),- Etching
(solution of 35% concentrated HCL (60%) and 35%
concentrated HNO3 (40%) for 2-3 min to produce a bright
surface.
23
FF FS FM
Fig.9
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Table 5. Radiography Test Results of Full Plate.Sample Id Film
Size (inch) Position Observation
FF 3 X 15 A/B Miner defect arereported andaccepted
withinstandard
FS 3 X 15 A/B
FM 3 X 15 A/B
FFFF
24
FSFS
FMFM
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25
Figure 10. . Plate less than 19mm Thickness Procedure
Qualification(Pressurevessel and boiler code. ASME, Section IX)
[25].
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Destructive TestingTable 6. Tensile Test Specimens
Sample IdTensile test photos
RemarksFirst set
FF Specimen break from parent metal
26
FS Specimen break from parent metal
FM Specimen break from parent metal
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Table- 7. Yield Strength and Tensile Strength for Welded
joints.Sample Id Set of
ExperimentsYield
Strength(MPa)
Avg. YieldStrength(MPa)
TensileStrength(MPa)
Avg. TensileStrength(MPa)
Observation
FF 1387
359611
565 Broken fromparent
330 519
382 517
27
FS 2
382
385517
568 Broken fromparent
388 619
FM 3375
379562
559 Broken fromparent
382 555
Average yield strength and tensile strength values are higher
for FS hybrid weld.
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Fig.11 Effect of wires on mechanical yieldstrength
Fig.12 Effect of wires on mechanical Tensilestrength.
300320340360380400420
FF FS FM
YS in
MPa
Consumables
500520540560580600
FF FS FM
TS in
MPa
Consumables
28
Fig.11 Effect of wires on mechanical yieldstrength
Fig.12 Effect of wires on mechanical Tensilestrength.
This may be due to the externally fine microstructure (ferrite,
Widmanstttenferrite, and acicular ferrite) developed.Additionally,
it is future conform through the weld metal chemical analysis as
shown intable 9.it was found that C-Mn-S for FS weld metal is
higher compared to filler metal.The variation in properties across
the weld can be attributed
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Table-8 %Elongation Area for welded Joints
SampleId
Set ofspecimen
%Elongation
Avg. %Elongation
FF1 25 232 21
FS1 08
152 22
FM1 20
232 26
29
05
1015202530
FF FS FM
% Elon
gation
ConsumablesFig.(13) Effect of wires on % Elongation
Result:- Percent elongation is higher forflux cored weld (FF) as
compare to hybridwelds
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Table-9 Joint efficiency of welded joint.
Sample Id Weld Joint Strengthin MPa
Joint Efficiency in %
FF 565.05 96
FS 568.00 96
FM 558.20 95
Result:- Joint efficiency of weldedjoint is defined as a ratio
of strengthof weld metal to the strength ofparent metal.Strength of
parent metal is590MPa.
Joint efficiency is very by 2%only.
100
30Fig. (14) Different wires on joint efficiency
Result:- Joint efficiency of weldedjoint is defined as a ratio
of strengthof weld metal to the strength ofparent metal.Strength of
parent metal is590MPa.
Joint efficiency is very by 2%only.
80859095
100
FF FS FM
Joint
Efficie
ncy
Consumables
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Table -8 Bend test photos
ID
Bend Test
RemarksFace bend Root BendSet. 1 Set. 2
FFPass
31
FSPass
FM Pass
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Table -9 Impact Test Results.
Weldingprocess
Charpy impact test at -49 C. energy absorbed in Joule
set of specimen Avg.Weld
set of specimen Avg.HAZI II II I I III
FF 46 44 38 43 32 38 36 35
FS 44 50 52 49 26 22 22 24
FM 20 24 18 21 24 28 22 25
60
32
(G) Impact test results Weld and HAZ
Fig.(15) Impact test results Weld and HAZ
Result:- Highest Impact value reported forFS welds and lowest
for FM welds. Whilein HAZ highest impact values reported
forFF..
1015202530354045505560
FF FS FM
Impa
ct Tes
t in J
Consumables
WELD
HAZ
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Vickers Hardness Measurement Specimens prepared for
macrostructure observation were utilized for VHN measurement.
Specification of the machine as follow. Vickers hardness was
measured as per standard ASTM,A 370-07 in both in both
transverse(weld metal, HAZ, and parent metal) direction and
vertical(root to filler pass)direction.
Each indentation was separated by 1mm at 10 Kg for macro
hardness and 300grms formicro hardness.
Equipment : ESEWAY-4000.Modal-4302 Load : 10 Kg & 300grm
Dwell Time : 15 Sec. Objective : 20 X
Specimens prepared for macrostructure observation were utilized
for VHN measurement.Specification of the machine as follow.
Vickers hardness was measured as per standard ASTM,A 370-07 in
both in bothtransverse(weld metal, HAZ, and parent metal) direction
and vertical(root to filler pass)direction.
Each indentation was separated by 1mm at 10 Kg for macro
hardness and 300grms formicro hardness.
Equipment : ESEWAY-4000.Modal-4302 Load : 10 Kg & 300grm
Dwell Time : 15 Sec. Objective : 20 X
33Fig- 16: Vicker hardness tester - (ESEWAY-4000.Modal-4302) at
PDPU
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Fig17. VHN at different (transverse direction) zones at
(HV10)
100115130145160175190205220235250265280
-15
-14
-13
-12
-11
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13
14 15
HV
10
Dist. from Center of weld to both side
FF
FS
FM
34
Fig 18. VHN at different (vertical direction) zones at
(HV10)
150165180195210225240255270285300
-5 -4 -3 -2 -1 0 1 2 3 4 5
HV
10
Dist. from Center of weld to both side
FF
FS
FM
Root side Filler side
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Fig 19. VHN at different (transverse direction) zones at
(HV0.3)
Fig 20. VHN at different (Vertical direction) zones at
(HV0.3)
100115130145160175190205220235250265280295310325340355370385400
-15
-14
-13
-12
-11
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13
14 15
HV
0.3
Dist. from Center of weld to both side
FF
FS
FM
35
Fig 20. VHN at different (Vertical direction) zones at
(HV0.3)
120140160180200220240260280300320340360380400
-5 -4 -3 -2 -1 0 1 2 3 4 5
HV
0.3
Dist. from Center of weld to both side
FF
FSFM
Root side Filler side
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Contentin %
FF FS FM
Filler
WireWeldedSample Filler Wire
WeldedSample Filler Wire
WeldedSample
Carbon 0.07 0.112 0.03 0.092 0.048 0.108
Manganese 1.44 1.510 1.29 1.415 1.375 1.309
TABLE 10. Chemical analysis of weld metal
36
Silicon 0.86 0.618 0.56 0.674 0.582 0.391
= increased and = decreased compared with filler wire %.
From above table , C-Mn-Si for FS welds metal is higher compared
to filler metal.
In second cases, C-Mn % for FF welds metal is higher compared to
filler metal, while Si islow record. C for FM weld higher while
Mn-Si is lower compared to filler metal.
-
From table 10, in some cause % for Manganese and % of silicon in
weld metal isreduced as compared to filler wire because of all this
element react with oxygenstrongly during welding.
The loss of manganese and silicon may be caused by oxidation
reactions in theweld pool: [20]
Carbon, decreases. the ductility, formability, weldability and
increases the strengthand hardenability.
Manganese slightly increases the strength of ferrite, and also
increases the hardnesspenetration of steel in the quench by
decreasing the critical quenching speed. Thisalso makes the steel
more stable in the quench
Silicon is used as a deoxidizer in the manufacture of steel. It
slightly increases the strength of ferrite, and when used in
conjunction with other
alloys can help increase the toughness and hardness penetration
of steel.
From table 10, in some cause % for Manganese and % of silicon in
weld metal isreduced as compared to filler wire because of all this
element react with oxygenstrongly during welding.
The loss of manganese and silicon may be caused by oxidation
reactions in theweld pool: [20]
Carbon, decreases. the ductility, formability, weldability and
increases the strengthand hardenability.
Manganese slightly increases the strength of ferrite, and also
increases the hardnesspenetration of steel in the quench by
decreasing the critical quenching speed. Thisalso makes the steel
more stable in the quench
Silicon is used as a deoxidizer in the manufacture of steel. It
slightly increases the strength of ferrite, and when used in
conjunction with other
alloys can help increase the toughness and hardness penetration
of steel.
37
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(a) Microstructure ofFCAWParent
(b) Microstructure of PM &HAZleft (interface)
(c) Microstructure ofTop run
Microstructure of the FF Samples at (200X)
Normalweld
38
(d) Microstructure ofMiddle run
(f) Microstructure of Root run
Hybridweld
(g) Microstructure ofPM &HAZ Right
(interface)
-
(a) Microstructure ofParent
(b) Microstructure of PM &HAZleft (interface)
(c) Microstructure ofTop run
Hybridweld
Microstructure of the FS Samples at (200X)
(d) Microstructure ofMiddle run
(e) Microstructure of Root run
Hybridweld
(f) Microstructure of PM &HAZ Right(interface)
-
(a) Microstructure ofParent (b) Microstructure of PM
&HAZ
left(interface)
(c) Microstructure ofTop run
Hybridweld
Microstructure of the FM Samples at (200X)
(d) Microstructure ofMiddle run
(g) Microstructure ofRoot run
(h) Microstructure ofPM &HAZ
Right (interface)(f) Microstructure ofMiddle run (50 X)
-
The properties of the steel depends upon the microstructure.
Decreasing the size of thegrains and decreasing the amount of
pearlite improve the strength, ductility andtoughness of the
steelMicrostructure investigation reflects the extremely fine grain
structure of weld and aswell HAZ of FS weld.It has two major
constituents, which are ferrite and pearlite.Its major components
include allotriomorphic ferrite, Widmansttten (called side
plateferrite) ferrite, and acicular ferrite.The dark regions are
the microstructure is the pearlite. it is made up from a
finemixture of ferrite and iron carbide.The light coloured region
is the ferrite. boundary ferrite is called
allotriomorphicferrite.
41
The properties of the steel depends upon the microstructure.
Decreasing the size of thegrains and decreasing the amount of
pearlite improve the strength, ductility andtoughness of the
steelMicrostructure investigation reflects the extremely fine grain
structure of weld and aswell HAZ of FS weld.It has two major
constituents, which are ferrite and pearlite.Its major components
include allotriomorphic ferrite, Widmansttten (called side
plateferrite) ferrite, and acicular ferrite.The dark regions are
the microstructure is the pearlite. it is made up from a
finemixture of ferrite and iron carbide.The light coloured region
is the ferrite. boundary ferrite is called
allotriomorphicferrite.
-
42
Figure13. Fracture morphology (SEM image) of tensile specimen
fractured at room temperature, (a) FF sample,(b) FS sample. (C) FM
sample. The inclusion is indicated by the arrow. The EDAX spectra
of the inclusions areshown in Fig
FF sample FS sample
-
In all sample, the results of the EDXanalyses indicated that the
inclusionscontained manganese, iron, carbon andnickel, silicon as
shown in Fig .
43
Small spots within the ferrite grains. These inclusions are
silicon oxides and manganeseoxides, and sulphides etc.The
difference in composition of the inclusions is due to the different
sources of theinclusions.In MAG, the Impurities mainly arose from
the shielding gas. In FCAW, the impuritiesmainly arose from the ux
and shielding gas. [18]
FM sample
-
Image Analyser ERDA, Baroda
Model: Olympus
Scanning ElectronMicroscope - PDPU
Model : ZEISS ULTRA 55 44
-
CONCLUSIONS The angular distortion is higher with flux cored
wire compare to hybrid weld. Pick temperature reported with flux
cored wire is higher compare to hybrid weld
which shown that high hear input with welding with flux cored
wire. Yield strength and tensile strength values are higher for
with FS hybrid weld. Percent elongation is higher for flux cored
wire as compare to hybrid welds During tensile test all specimens
failed from parent material; means welded joints
are stronger then parent metal. Samples welded with different
consumables shows good integrity of welded
joints during bend test. Excellent impact toughness of the weld
metal reported for the FS hybrid welds
compared to other cases. Higher macro and micro hardness value
reported for flux cored welds compare to
others hybrid welds. Weld metal microstructure confirm the
presence of allotriomorphic ferrite,
Widmansttten ferrite, and acicular ferrite in the weld
metal.
The angular distortion is higher with flux cored wire compare to
hybrid weld. Pick temperature reported with flux cored wire is
higher compare to hybrid weld
which shown that high hear input with welding with flux cored
wire. Yield strength and tensile strength values are higher for
with FS hybrid weld. Percent elongation is higher for flux cored
wire as compare to hybrid welds During tensile test all specimens
failed from parent material; means welded joints
are stronger then parent metal. Samples welded with different
consumables shows good integrity of welded
joints during bend test. Excellent impact toughness of the weld
metal reported for the FS hybrid welds
compared to other cases. Higher macro and micro hardness value
reported for flux cored welds compare to
others hybrid welds. Weld metal microstructure confirm the
presence of allotriomorphic ferrite,
Widmansttten ferrite, and acicular ferrite in the weld
metal.
45
-
While comparing the mechanical properties of the FF welds with
FS and FM. It wasfound that FS weld is better compared to others in
terms of YS, TS JE and weldimpact. This may be due to the
externally fine microstructure (ferrite,Widmansttten ferrite, and
acicular ferrite) developed.
Additionally, it is future conform through the weld metal
chemical analysis asshown in table 9.it was found that C-Mn-S for
FS weld metal is higher compared tofiller metal.
46
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Paper submitted
1.International Journal of Pressure Vessels and Piping
(ELSEVIER).Impact Factor: 1.532,Date-26/12/2014, DC ON
12/12/2014
Title: The effect of welding consumables on the Mechanical and
Metallurgicalproperties of carbon Steel Material. Current Status:
Paper under review.
2. Journal of Pressure Vessel Technology ,ASMEsubmitted on
Date-13/04/2015
Title: The effect of Hybrid Weldments on the Mechanical and
Metallurgical.Properties of carbon Steel Material.
Current Status: comments received from reviewer.
47
Paper submitted
1.International Journal of Pressure Vessels and Piping
(ELSEVIER).Impact Factor: 1.532,Date-26/12/2014, DC ON
12/12/2014
Title: The effect of welding consumables on the Mechanical and
Metallurgicalproperties of carbon Steel Material. Current Status:
Paper under review.
2. Journal of Pressure Vessel Technology ,ASMEsubmitted on
Date-13/04/2015
Title: The effect of Hybrid Weldments on the Mechanical and
Metallurgical.Properties of carbon Steel Material.
Current Status: comments received from reviewer.
-
Originality AcceptableSignificance AcceptableScientific
relevance AcceptableCompleteness AcceptableAcknowledgment of the
Work of others by References AcceptableOrganization MarginalClarity
of Writing MarginalClarity of Tables, Graphs, and Illustrations
MarginalIn your opinion, is the technical treatment plausible and
free of technicalerrors?
Yes
Reviewer 1:
48
In your opinion, is the technical treatment plausible and free
of technicalerrors?
Yes
Have you checked the equations? NoAre you aware of prior
publication or presentation of this work? NoIs the work free of
commercialism? YesIs the title brief and descriptive? YesDoes the
abstract clearly indicate objective, scope, and results? Yes
This paper is Not Acceptable (Revision required; resubmit as
Tech. Brief) . The qualityof the paper is Good.
Recommendation
The work appears to be original and meaningful.
-
Originality Acceptable
Significance Acceptable
Scientific relevance Acceptable
Completeness Marginal
Acknowledgment of the Work of others by References Marginal
Organization Acceptable
Clarity of Writing Poor
Clarity of Tables, Graphs, and Illustrations Marginal
In your opinion, is the technical treatment plausible and free
of technical errors? Yes
Reviewer 2:
49
In your opinion, is the technical treatment plausible and free
of technical errors? Yes
Have you checked the equations? Yes
Are you aware of prior publication or presentation of this work?
No
Is the work free of commercialism? Yes
Is the title brief and descriptive? Yes
Does the abstract clearly indicate objective, scope, and
results? No
This paper is Not Acceptable (Revision and resubmitted required)
. The quality of thepaper is Average.
Recommendation
-
Internal Assessment seminar topics
(1) Non- Destructive testing of welds- all.(Delivered on
05/09/2013)(2) Heat Flow during welding. (Delivered on
10/10/2013)(3) M.Tech presentation. (Delivered on 27/01/ 2014)(4)
Destructive testing of welds- all. (Delivered 15th May 2014)(5)
Welding symbol (Delivered 29th Des 2014)(6) Welding Metallurgy
(will be deliver before 11nd June2015)
Internal Assessment seminar topics
(1) Non- Destructive testing of welds- all.(Delivered on
05/09/2013)(2) Heat Flow during welding. (Delivered on
10/10/2013)(3) M.Tech presentation. (Delivered on 27/01/ 2014)(4)
Destructive testing of welds- all. (Delivered 15th May 2014)(5)
Welding symbol (Delivered 29th Des 2014)(6) Welding Metallurgy
(will be deliver before 11nd June2015)
-
References
1. American Welding Society - Welding Hand book, Welding
Processes, Eighth Edition - Vol.II, pp 110, pp 157-190.2. American
Society of Metals Handbook, Vol. 6 Welding, Brazing and Soldering,
Published in 1993, pp 582-583.3. www.esabna.com, "Advantages and
Disadvantages of metal cored wire".4. Nasir Ahmed, "New development
in advance welding", Pub. Wood Head publishing limited Cambridge,
England; pp 23.5. Stanley E. Ferree, Michael S, Sierdzinski,
"Stainless steel metal cored wires for welding automotive exhaust
systems" ESAB
Welding and Cutting Products, Hanover (PA) USA. Svetsaren nr i ,
2000, pp 15-18.6. Kevin A. Lyttle, Praxair, Inc Senior Development
Associate; "Metal Cored Wire: Where Do They Fit In Your Future?"
Reprinted
from Welding Journal, Oct. 1996, pp 35-38.7. www.esabmanualcom,
"Flux Core arc Welding, ESAB".8. David Widgery; Tubular wire
welding, Jaico Publishing House.9. Washington alloy co.
www.weldingwire.com.10. Avesatar welding www.avestarwelding.com.11.
BOC, IPRM 2006: Section 4: Welding processes.12. BOC, AU: IPRM
2007: Section 8: Consumables.13. M. Suban, J. Tusek, "Dependance of
melting rate in MIG/MAG welding on the type of shielding gas used",
Journal of Materials
Processing Technology 119 (2001), pp 185-192.14. American
Society of Metals Handbook, Vol. 6 Welding, Brazing and Soldering,
Published in 1993, pp 163-174.15. Tom Myers,"Choosing a shielding
Gas for FCAW", A senior application engineer, The Lincoln Electric
Co; Cleveland, Ohio.16. John Norrish, -Advanced welding processes
technologies and process control", Pub. Wood.17. Head publishing
limited Cambridge", England pp 108.18. V. V. Vaidya, "Theory and
practice of shielding gas mixtures for semiautomatic welds",
Director, welding Technology and Business
Development, Air Liquide Canada Inc., Canada.19. M Menzel, "The
influence of individual components of an industrial gas mixture on
the welding process and the properties of
welded joints". Linde Gas Poland; Welding International 2003 17
(4) 262-264.20. .S. Mukhopadhyay and T.K.Pal.; "Effect of shielding
gas mixture on gas metal arc welding of HSLA steel using solid and
flux-cored
wires". Welding Technology Centre, Metallurgical Engineering
Department, Jadavpur University, Kolkata.21. AMOS DAVIS, business
development manager, "Optimizing Metal Cored Performance" Hobart
Brothers Company, Feb 1, 2009;
12:00 PM.22. W. F. Garth Stapon, "Using Flux cored and Metal
Cored Wire". Praxair. Inc. Marketing Manager Metal Fabrication;
Reprinted from
Practical Welding Today Jan/Feb 2000.23. V. Vel Murugan and V.
Gunaraj, "Effect of process parameters on Angular Distortion of gas
metal arc welded structural steel plates",
Welding Journal, November 2005.51
References
1. American Welding Society - Welding Hand book, Welding
Processes, Eighth Edition - Vol.II, pp 110, pp 157-190.2. American
Society of Metals Handbook, Vol. 6 Welding, Brazing and Soldering,
Published in 1993, pp 582-583.3. www.esabna.com, "Advantages and
Disadvantages of metal cored wire".4. Nasir Ahmed, "New development
in advance welding", Pub. Wood Head publishing limited Cambridge,
England; pp 23.5. Stanley E. Ferree, Michael S, Sierdzinski,
"Stainless steel metal cored wires for welding automotive exhaust
systems" ESAB
Welding and Cutting Products, Hanover (PA) USA. Svetsaren nr i ,
2000, pp 15-18.6. Kevin A. Lyttle, Praxair, Inc Senior Development
Associate; "Metal Cored Wire: Where Do They Fit In Your Future?"
Reprinted
from Welding Journal, Oct. 1996, pp 35-38.7. www.esabmanualcom,
"Flux Core arc Welding, ESAB".8. David Widgery; Tubular wire
welding, Jaico Publishing House.9. Washington alloy co.
www.weldingwire.com.10. Avesatar welding www.avestarwelding.com.11.
BOC, IPRM 2006: Section 4: Welding processes.12. BOC, AU: IPRM
2007: Section 8: Consumables.13. M. Suban, J. Tusek, "Dependance of
melting rate in MIG/MAG welding on the type of shielding gas used",
Journal of Materials
Processing Technology 119 (2001), pp 185-192.14. American
Society of Metals Handbook, Vol. 6 Welding, Brazing and Soldering,
Published in 1993, pp 163-174.15. Tom Myers,"Choosing a shielding
Gas for FCAW", A senior application engineer, The Lincoln Electric
Co; Cleveland, Ohio.16. John Norrish, -Advanced welding processes
technologies and process control", Pub. Wood.17. Head publishing
limited Cambridge", England pp 108.18. V. V. Vaidya, "Theory and
practice of shielding gas mixtures for semiautomatic welds",
Director, welding Technology and Business
Development, Air Liquide Canada Inc., Canada.19. M Menzel, "The
influence of individual components of an industrial gas mixture on
the welding process and the properties of
welded joints". Linde Gas Poland; Welding International 2003 17
(4) 262-264.20. .S. Mukhopadhyay and T.K.Pal.; "Effect of shielding
gas mixture on gas metal arc welding of HSLA steel using solid and
flux-cored
wires". Welding Technology Centre, Metallurgical Engineering
Department, Jadavpur University, Kolkata.21. AMOS DAVIS, business
development manager, "Optimizing Metal Cored Performance" Hobart
Brothers Company, Feb 1, 2009;
12:00 PM.22. W. F. Garth Stapon, "Using Flux cored and Metal
Cored Wire". Praxair. Inc. Marketing Manager Metal Fabrication;
Reprinted from
Practical Welding Today Jan/Feb 2000.23. V. Vel Murugan and V.
Gunaraj, "Effect of process parameters on Angular Distortion of gas
metal arc welded structural steel plates",
Welding Journal, November 2005.
-
26. 26. ASTM-A ferrous metals 2006 SA 516 Gr-70.27. Gas metal
are welding of carbon steel (PRAXAIR).28. Mario Teske and Fabio
Martins, The influence of the shielding gas composition on GMA
welding of ASTM A 516 steel. Federal Technological
University of Parana, Campus Curitiba, Brazil.29. Cicero Murta
Diniz Starling, Paulo Jose Modenesi, and Tadeu Messias Donizete
Borba, Comparison of operational performance and bead
characteristics
when welding with different tubular wires, Welding
international, Vol. 24, No 8, August 2010, 579-592.30. R. M. Mirza
and R. Gee;Effects of shielding gases on weld diffusible hydrogen
contents using cored wire; Science and Technology of welding
and
joining, 1999, vol. 4, no.2.31. Ravi Menon,; Recent advances in
cored wires for hardfacing. Vice President, Technology, Stoody Co;
a Thermadyne company, Bowling Green.32. N. M. Ramini DE Rissone; H.
G. Svoboda; E. S. Surian, and L. A. DE Vedia; Influence of
procedure variables on C-Mn-Ni-Mo metal cored wire ferrites
all weld metal. Supplement to the welding journal, September
2005.33. Lucilene de Oliveira Rodrigues, Anderson Paulo de Paiva
and Sebastiao Carlos de Costa; Optimization of the FCAW process by
bead geometry
analysis, Welding International, Vol.23, No.4, Aprial 2009,
261-269.34. D. D. Harwig; D. P. Longeneker and J. H. Cruz; Effect
of welding parameters and electrode atmospheric exposure on the
diffusible hydrogen content of
shielding flux cored arc welds, AWS welding Journal, September
1999.35. K. S. Bang; D. H. Jung; C. Park and W. S. Chang; Effect of
welding parameters on tensile strength of weld metal in flux cored
arc welding, Science and
Technology of welding and joining, 2008, vol. 13, no.6, 509.36.
T. Kannan & J. Yoganandh, Effect of process parameters on clad
bead geometry and its shape relationships of stainless steel
claddings deposited by
GMAW, Int Adv Manuf Technology (2010), 30: 1083-1095.37. ESAB;
Welding Handbook; Eighth edition.38. Her-Yueh Huang; Effects of
activating flux on the welded joint characteristics in gas metal
arc welding. Department of Materials Science and
Engineering, National Formosa University, Yunlin 632, Taiwan.39.
The ABC's of Arc Welding; KOBELCO WELDING TODAY.40.
www.wikipedia.com Equivalent Carbon Content.41. H. K. D. H.
Bhadeshia and Sir Robert Honeycombe; Steels: Microstructure and
Properties: Third edition; Published by Elsevier Ltd. 2006.42. Flux
Cored Arc Welding Equipment, Setup, and Operation Chapter no 3.43.
Welding Kita-Shinagawa, Shinagawa-Ku Essential Factors in Gas Metal
Arc 2011 by Kobe Steel, Ltd Fourth Edition , Tokyo, 141-8688
Japan.44. Shielding Gases Selection Manual (Praxair).45. British
patent 8580854, Mar 29, 1957.46. Welding Design and Fabrication, a
Penton Media, Inc. publication. May 1999 6/8/1999, New AWS
Specs-Electrode Selection.47. Nick Kapustka Arc Welding
Capabilities at EWI, November 29, 2012 .ewi.org 614.688.5000.48.
Jeff Nadzam, Senior Application Engineer Lincon electrical, Gas
Metal Arc Welding , Carbon, Low Alloy, and Stainless Steels and
Aluminum, MIG
C4.200 9/06.49. Syarul Asraf Mohamat,, Izatul Aini Ibrahim, ,
Amalina Amir , Abdul Ghalib The Effect of Flux Core Arc Welding
(FCAW) processes on different
parameters SciVerse ScienceDirect , International Symposium on
Robotics and Intelligent Sensors 2012 (IRIS 2012) Procedia
Engineering 41 ( 2012 )1497 1501.
50. Vishvesh J Badheka , Hardik Vyas Comparisons of GMA, FCA and
MCA weldments of SA516 Gr70 Steel Material.51. Ramy Gadallah ,
Raouf Fahmy ,Tarek Khalifa, Alber Sadek Influence of Shielding Gas
Composition on the Properties of Flux-Cored Arc Welds of
Plain Carbon Steel.International Journal of Engineering and
Technology Innovation, vol. 2, no. 1, 2012, pp. 01-12.
52. ASME. Pressure vessel and boiler code. New York (NY): ASME,
Section IX.53. K.E. Dorschu. Factors affecting weld metal
properties in carbon and low alloy pressure vessel steels.
sponsored by the pressure vessel research committee
of the welding research council, WRC bulletin 231.
26. 26. ASTM-A ferrous metals 2006 SA 516 Gr-70.27. Gas metal
are welding of carbon steel (PRAXAIR).28. Mario Teske and Fabio
Martins, The influence of the shielding gas composition on GMA
welding of ASTM A 516 steel. Federal Technological
University of Parana, Campus Curitiba, Brazil.29. Cicero Murta
Diniz Starling, Paulo Jose Modenesi, and Tadeu Messias Donizete
Borba, Comparison of operational performance and bead
characteristics
when welding with different tubular wires, Welding
international, Vol. 24, No 8, August 2010, 579-592.30. R. M. Mirza
and R. Gee;Effects of shielding gases on weld diffusible hydrogen
contents using cored wire; Science and Technology of welding
and
joining, 1999, vol. 4, no.2.31. Ravi Menon,; Recent advances in
cored wires for hardfacing. Vice President, Technology, Stoody Co;
a Thermadyne company, Bowling Green.32. N. M. Ramini DE Rissone; H.
G. Svoboda; E. S. Surian, and L. A. DE Vedia; Influence of
procedure variables on C-Mn-Ni-Mo metal cored wire ferrites
all weld metal. Supplement to the welding journal, September
2005.33. Lucilene de Oliveira Rodrigues, Anderson Paulo de Paiva
and Sebastiao Carlos de Costa; Optimization of the FCAW process by
bead geometry
analysis, Welding International, Vol.23, No.4, Aprial 2009,
261-269.34. D. D. Harwig; D. P. Longeneker and J. H. Cruz; Effect
of welding parameters and electrode atmospheric exposure on the
diffusible hydrogen content of
shielding flux cored arc welds, AWS welding Journal, September
1999.35. K. S. Bang; D. H. Jung; C. Park and W. S. Chang; Effect of
welding parameters on tensile strength of weld metal in flux cored
arc welding, Science and
Technology of welding and joining, 2008, vol. 13, no.6, 509.36.
T. Kannan & J. Yoganandh, Effect of process parameters on clad
bead geometry and its shape relationships of stainless steel
claddings deposited by
GMAW, Int Adv Manuf Technology (2010), 30: 1083-1095.37. ESAB;
Welding Handbook; Eighth edition.38. Her-Yueh Huang; Effects of
activating flux on the welded joint characteristics in gas metal
arc welding. Department of Materials Science and
Engineering, National Formosa University, Yunlin 632, Taiwan.39.
The ABC's of Arc Welding; KOBELCO WELDING TODAY.40.
www.wikipedia.com Equivalent Carbon Content.41. H. K. D. H.
Bhadeshia and Sir Robert Honeycombe; Steels: Microstructure and
Properties: Third edition; Published by Elsevier Ltd. 2006.42. Flux
Cored Arc Welding Equipment, Setup, and Operation Chapter no 3.43.
Welding Kita-Shinagawa, Shinagawa-Ku Essential Factors in Gas Metal
Arc 2011 by Kobe Steel, Ltd Fourth Edition , Tokyo, 141-8688
Japan.44. Shielding Gases Selection Manual (Praxair).45. British
patent 8580854, Mar 29, 1957.46. Welding Design and Fabrication, a
Penton Media, Inc. publication. May 1999 6/8/1999, New AWS
Specs-Electrode Selection.47. Nick Kapustka Arc Welding
Capabilities at EWI, November 29, 2012 .ewi.org 614.688.5000.48.
Jeff Nadzam, Senior Application Engineer Lincon electrical, Gas
Metal Arc Welding , Carbon, Low Alloy, and Stainless Steels and
Aluminum, MIG
C4.200 9/06.49. Syarul Asraf Mohamat,, Izatul Aini Ibrahim, ,
Amalina Amir , Abdul Ghalib The Effect of Flux Core Arc Welding
(FCAW) processes on different
parameters SciVerse ScienceDirect , International Symposium on
Robotics and Intelligent Sensors 2012 (IRIS 2012) Procedia
Engineering 41 ( 2012 )1497 1501.
50. Vishvesh J Badheka , Hardik Vyas Comparisons of GMA, FCA and
MCA weldments of SA516 Gr70 Steel Material.51. Ramy Gadallah ,
Raouf Fahmy ,Tarek Khalifa, Alber Sadek Influence of Shielding Gas
Composition on the Properties of Flux-Cored Arc Welds of
Plain Carbon Steel.International Journal of Engineering and
Technology Innovation, vol. 2, no. 1, 2012, pp. 01-12.
52. ASME. Pressure vessel and boiler code. New York (NY): ASME,
Section IX.53. K.E. Dorschu. Factors affecting weld metal
properties in carbon and low alloy pressure vessel steels.
sponsored by the pressure vessel research committee
of the welding research council, WRC bulletin 231.52
-
53
-
EFFECT OF ALLOYING ELEMENT IN STEEL .[53]Carbon (C): Carbon is
an element whose presence is imperative in all steel. Indeed,
carbon is theprinciple hardening element of steel. That is, this
alloying element determines the level of hardness or strength that
can
be attained by quenching. Furthermore, carbon is essential for
the formation ofcementite (as well as other carbides) and of
pearlite, spheridite, bainite, and iron-carbon martensite, with
martensite being the hardest of the microstructures.
Carbon is also responsible for increase in tensile strength,
hardness, resistance towear and abrasion.
However, when present in high quantities it affects the
ductility, the toughness andthe machinability of steel.
They are described as follows:Low Carbon: Under 0.4 percent
Medium Carbon: 0.4 - 0.6 percent High Carbon: 0.7 - 1.5
percent Carbon is the single most important alloying element in
steel.
EFFECT OF ALLOYING ELEMENT IN STEEL .[53]Carbon (C): Carbon is
an element whose presence is imperative in all steel. Indeed,
carbon is theprinciple hardening element of steel. That is, this
alloying element determines the level of hardness or strength that
can
be attained by quenching. Furthermore, carbon is essential for
the formation ofcementite (as well as other carbides) and of
pearlite, spheridite, bainite, and iron-carbon martensite, with
martensite being the hardest of the microstructures.
Carbon is also responsible for increase in tensile strength,
hardness, resistance towear and abrasion.
However, when present in high quantities it affects the
ductility, the toughness andthe machinability of steel.
They are described as follows:Low Carbon: Under 0.4 percent
Medium Carbon: 0.4 - 0.6 percent High Carbon: 0.7 - 1.5
percent Carbon is the single most important alloying element in
steel.
54
-
Manganese (Mn):Increases the strength, shock resistance,
toughness, hardenability, weldebility, hotformability, no change in
ductility. In addition Mn is a strong austenite former by reducing
the eutectoid temperaturebelow to room temperature.Manganese
slightly increases the strength of ferrite, and also increases the
hardnesspenetration of steel in the quench by decreasing the
critical quenching speed. This alsomakes the steel more stable in
the quench.
Sulfur (S):The excess sulfur reduces the ability for hot (900C)
deformation of steel forming thebrittle FeS phase at the grain
boundaries (hot brittleness).
The solubility of S is higher than C therefore it restricts the
formation of pearlite in thezones with higher S contents, leading a
banded structure of pearlite and ferrite.(Macroscopy experiment:
flow lines). This causes severe anisotropy in the mechanicalprop of
steel therefore S content is limited 0.035%.
However, 0.3% S may be added to free cutting steels to increase
the chip formationthus the machinability
55
Manganese (Mn):Increases the strength, shock resistance,
toughness, hardenability, weldebility, hotformability, no change in
ductility. In addition Mn is a strong austenite former by reducing
the eutectoid temperaturebelow to room temperature.Manganese
slightly increases the strength of ferrite, and also increases the
hardnesspenetration of steel in the quench by decreasing the
critical quenching speed. This alsomakes the steel more stable in
the quench.
Sulfur (S):The excess sulfur reduces the ability for hot (900C)
deformation of steel forming thebrittle FeS phase at the grain
boundaries (hot brittleness).
The solubility of S is higher than C therefore it restricts the
formation of pearlite in thezones with higher S contents, leading a
banded structure of pearlite and ferrite.(Macroscopy experiment:
flow lines). This causes severe anisotropy in the mechanicalprop of
steel therefore S content is limited 0.035%.
However, 0.3% S may be added to free cutting steels to increase
the chip formationthus the machinability
-
Silicone (Si): Silicon is used as a deoxidizer in the
manufacture of steel. It slightly increases the strength of
ferrite, and when used in conjunction with other
alloys can help increase the toughness and hardness penetration
of steel. It increases strength, decreases the weldability,
magnetic losses, oxide formation
affinity, no change in ductility. In addition Si has higher
affinity to O than carbon therefore used as deoxizing agent
(semi-killed steels). It is also austenite former agent leading
the nucleation of austenite grain in many
size yielding finer grain size.Copper (Cu):
Copper The addition of copper in amounts of 0.2 to 0.5 percent
primarily improvessteels resistance to atmospheric corrosion. It
should be noted that with respect toknife steels, copper has a
detrimental effect to surface quality and to hot-workingbehavior
due to migration into the grain boundaries of the steel.
Copper (Cu): restricted to max. 0.35%. Up to 0.2 % provides some
resistanceagainst to atmospheric corrosion. Not desired in spring
steels.
Silicone (Si): Silicon is used as a deoxidizer in the
manufacture of steel. It slightly increases the strength of
ferrite, and when used in conjunction with other
alloys can help increase the toughness and hardness penetration
of steel. It increases strength, decreases the weldability,
magnetic losses, oxide formation
affinity, no change in ductility. In addition Si has higher
affinity to O than carbon therefore used as deoxizing agent
(semi-killed steels). It is also austenite former agent leading
the nucleation of austenite grain in many
size yielding finer grain size.Copper (Cu):
Copper The addition of copper in amounts of 0.2 to 0.5 percent
primarily improvessteels resistance to atmospheric corrosion. It
should be noted that with respect toknife steels, copper has a
detrimental effect to surface quality and to hot-workingbehavior
due to migration into the grain boundaries of the steel.
Copper (Cu): restricted to max. 0.35%. Up to 0.2 % provides some
resistanceagainst to atmospheric corrosion. Not desired in spring
steels.
56
-
Chromium (Cr): As the Cr content increases, strength,
hardenability, corrosion resistance, high
temperature strength, decreases the oxide formation tendency.
(forms a verycoherent oxide layer on the surface preventing further
oxidation-- in stainlesssteels).
It is also strong carbide former as an essential factor behaving
as a strong secondphase particle, therefore, obstructs the
dislocation motion particularly at elevatedtemperatures. Also
nitride former and used in nitriding steels.
Chromium As with manganese, chromium has a tendency to increase
hardnesspenetration. This element has many interesting effects on
steel.
Phosphorus It increases strength and hardness and decreases
ductility and notch impact
toughness of steel. The adverse effects on ductility and
toughness are greater in quenched and
tempered higher-carbon steels.
Nickel Nickel is a ferrite strengthener. Nickel does not form
carbides in steel. It remains
in solution in ferrite, strengthening and toughening the ferrite
phase. Nickelincreases the harden ability and impact strength of
steels.
Chromium (Cr): As the Cr content increases, strength,
hardenability, corrosion resistance, high
temperature strength, decreases the oxide formation tendency.
(forms a verycoherent oxide layer on the surface preventing further
oxidation-- in stainlesssteels).
It is also strong carbide former as an essential factor behaving
as a strong secondphase particle, therefore, obstructs the
dislocation motion particularly at elevatedtemperatures. Also
nitride former and used in nitriding steels.
Chromium As with manganese, chromium has a tendency to increase
hardnesspenetration. This element has many interesting effects on
steel.
Phosphorus It increases strength and hardness and decreases
ductility and notch impact
toughness of steel. The adverse effects on ductility and
toughness are greater in quenched and
tempered higher-carbon steels.
Nickel Nickel is a ferrite strengthener. Nickel does not form
carbides in steel. It remains
in solution in ferrite, strengthening and toughening the ferrite
phase. Nickelincreases the harden ability and impact strength of
steels.
57
-
The Iron-Iron Carbide Diagram A map of the temperature at which
different phase changes occur on very
slow heating and cooling in relation to Carbon, is called Iron-
CarbonDiagram.
Iron- Carbon diagram shows the type of alloys formed under very
slow cooling, proper heat-treatment temperature and how the
properties of steels and cast irons can be radically changed
by heat-treatment. Plain carbon steels are generally defined as
being those alloys of iron
and carbon which contain up to 2.0% carbon The pure metal Iron,
at temperatures below 910C, has a
body-centred cubic structure, and if we heat it to above
thistemperature the structure will change to one which is face
centredcubic.
A map of the temperature at which different phase changes occur
on veryslow heating and cooling in relation to Carbon, is called
Iron- CarbonDiagram.
Iron- Carbon diagram shows the type of alloys formed under very
slow cooling, proper heat-treatment temperature and how the
properties of steels and cast irons can be radically changed
by heat-treatment. Plain carbon steels are generally defined as
being those alloys of iron
and carbon which contain up to 2.0% carbon The pure metal Iron,
at temperatures below 910C, has a
body-centred cubic structure, and if we heat it to above
thistemperature the structure will change to one which is face
centredcubic.
-
IRON IRON-CARBON DIAGRAM
Austenite
Pearlite andCementine
Eutecticeutectoid
Ferrite
Steel Cast iron
Pearlite
Pearlite andCarbide
-
The Iron-Iron Carbide Diagram
The diagram shows three horizontal lines which indicate
isothermal reactions (oncooling / heating):
First horizontal line is at 1490C, where peritectic reaction
takes place:Liquid + austenite
Second horizontal line is at 1130C, where eutectic reaction
takes place:liquid austenite + cementite
Third horizontal line is at 723C, where eutectoid reaction takes
place:austenite pearlite (mixture of ferrite & cementite).
The diagram shows three horizontal lines which indicate
isothermal reactions (oncooling / heating):
First horizontal line is at 1490C, where peritectic reaction
takes place:Liquid + austenite
Second horizontal line is at 1130C, where eutectic reaction
takes place:liquid austenite + cementite
Third horizontal line is at 723C, where eutectoid reaction takes
place:austenite pearlite (mixture of ferrite & cementite).
-
61
-
The solid solution formed when carbon atoms are absorbed into
the face-centred cubicstructure of iron is called Austenite and the
extremely low level of solid solution formedwhen carbon dissolves
in body-centred cubic iron is called Ferrite.
For many practical purposes we can regard ferrite as having the
same properties as pureiron.the symbol ('gamma') is used to denote
both the face-centred cubic form of iron and thesolid solution
austenite, whilst the symbol ('alpha') is used to denote both
thebody-centred cubic form of iron existing below 910C and the
solid-solution ferrite
62
-
Definition of structures
Ferrite is known as solid solution. It is an interstitial solid
solution of a small amount of carbon dissolved
in (BCC) iron. stable form of iron below 912 deg.C The maximum
solubility is 0.025 % C at 723C and it dissolves only
0.008 % C at room temperature. It is the softest structure that
appears on the diagram.
Ferrite is known as solid solution. It is an interstitial solid
solution of a small amount of carbon dissolved
in (BCC) iron. stable form of iron below 912 deg.C The maximum
solubility is 0.025 % C at 723C and it dissolves only
0.008 % C at room temperature. It is the softest structure that
appears on the diagram.
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Definition of structures
Pearlite is the eutectoid mixture containing 0.80% C and is
formed at 723C on very slow cooling.
It is a very fine platelike or lamellar mixture offerrite and
cementite.
The white ferritic background or matrix containsthin plates of
cementite (dark).
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Pearlite is the eutectoid mixture containing 0.80% C and is
formed at 723C on very slow cooling.
It is a very fine platelike or lamellar mixture offerrite and
cementite.
The white ferritic background or matrix containsthin plates of
cementite (dark).
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Austenite is an interstitial solid solution of Carbon dissolved
in (F.C.C.) iron.Maximum solubility is 2.0 % C at 1130C.High
formability, most of heat treatments begin with this single
phase.It is normally not stable at room temperature. But, under
certain conditions it is possibleto obtain austenite at room
temperature.
Cementite or iron carbide, is very hard, brittle
intermetalliccompound of iron & carbon, as Fe3C, contains 6.67
% C.It is the hardest structure that appears on the diagram,exact
melting point unknown.Its crystal structure is orthorhombic. It is
haslow tensile strength (approx. 5,000 psi), buthigh compressive
strength.
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Cementite or iron carbide, is very hard, brittle
intermetalliccompound of iron & carbon, as Fe3C, contains 6.67
% C.It is the hardest structure that appears on the diagram,exact
melting point unknown.Its crystal structure is orthorhombic. It is
haslow tensile strength (approx. 5,000 psi), buthigh compressive
strength.
Martensite - a super-saturated solid solution of carbon in
ferrite.It is formed when steel is cooled so rapidly that the
change from austenite to pearlite issuppressed.The interstitial
carbon atoms distort the BCC ferrite into a BC-tetragonal
structure(BCT).; responsible for the hardness of quenched
steel.
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Principal phases of steel and their Characteristics
Phase Crystal structure Characteristics
Ferrite BCC Soft, ductile, magnetic
Austenite FCC Soft, moderate strength,non-magnetic
Cementite Compound of Iron &Carbon Fe3CHard
&brittleCementite Compound of Iron &Carbon Fe3CHard
&brittle
Hypo-eutectoid steels: Steels having less than 0.8% carbon are
called hypo-eutectoid steels (hypo means "less than").
Hyper-eutectoid steels (hyper means "greater than") are those
that contain morethan the eutectoid amount of Carbon.
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In arc welding, energy is transferred from the welding electrode
to the basemetal by an electric arc.Heat input is a relative
measure of the energy transferred per unit length ofweld.It is an
important characteristic because, like preheat and interpass
temperature,it influences the cooling rate, which may affect the
mechanical properties andmetallurgical structure of the weld and
the HAZ (see Figure 1). Heat input is typically calculated as the
ratio of the power (i.e., voltage xcurrent) to the velocity of the
heat source (i.e., the arc) as follows:
Cooling Rate is a Function of Heat Input
67
In arc welding, energy is transferred from the welding electrode
to the basemetal by an electric arc.Heat input is a relative
measure of the energy transferred per unit length ofweld.It is an
important characteristic because, like preheat and interpass
temperature,it influences the cooling rate, which may affect the
mechanical properties andmetallurgical structure of the weld and
the HAZ (see Figure 1). Heat input is typically calculated as the
ratio of the power (i.e., voltage xcurrent) to the velocity of the
heat source (i.e., the arc) as follows:
H = heat input (kJ/in or kJ/mm)E = arc voltage (volts)I =
current (amps)S = travel speed (in/min or mm/min)
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The effect of heat input on cooling rate is similar to that of
the preheattemperature.As either the heat input or the preheat
temperature increases, the rate of coolingdecreases for a given
base metal thickness.
These two variables interact with others such as material
thickness, specificheat, density, and thermal conductivity to
influence the cooling rate.
The following proportionality function shows this relationship
between preheattemperature, heat input and cooling rate:
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The effect of heat input on cooling rate is similar to that of
the preheattemperature.As either the heat input or the preheat
temperature increases, the rate of coolingdecreases for a given
base metal thickness.
These two variables interact with others such as material
thickness, specificheat, density, and thermal conductivity to
influence the cooling rate.
The following proportionality function shows this relationship
between preheattemperature, heat input and cooling rate:
R = cooling rate (F/sec or C/sec)To = preheat temperature (F or
C)H = heat input (kJ/in or kJ/mm)
-
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The cooling rate is a primary factor that determines the final
metallurgical structure of theweld and heat affected zone (HAZ),
and is especially important with heat-treated steels.
When welding quenched and tempered steels, for example, slow
cooling rates (resultingfrom high heat inputs) can soften the
material adjacent to the weld, reducing the load-carrying capacity
of the connection.