A Study of the Effect Of Extrusion Parameters On the ... · PDF fileA Study of the Effect Of Extrusion Parameters On the Properties Of Extruded Zr-2.5Nb Pressure Tubes N Saibaba Chief

A Study of the Effect Of Extrusion Parameters yOn the Properties Of Extruded

Zr-2.5Nb Pressure Tubes

N SaibabaChief Executive

Nuclear Fuel ComplexHyderabad-INDIA

ASTM STP 4th t 7th F b 2013ASTM –STP-4th to 7th Feb 2013

Hot Extrusion is the process by which a block of metal or

HOT EXTRUSIONHot Extrusion is the process by which a block of metal oralloy is reduced in X-section by forcing it to flow through a dieorifice under high pressure and above Recrystallizationorifice under high pressure and above Recrystallizationtemperature. It is used to produce long straight, semi-finishedproducts such as Bars, Solids & Hollow sections & tubes.

Multi axial compression in Extrusion is responsible for veryhigh strain in extrusion.Workability: “Deformation to the point of Fracture” increaseswith increasing mean pressure or hydrostatic pressure

m = (1 + 2 + 3 ) / 3or decreasing relative mean valueor decreasing relative mean value

Mean value = m / Kƒ

STATE OF STRESS IN VARIOUS METALWORKING PROCESSESMETALWORKING PROCESSES

f COMPRESSIVE HYDROSTATIC STRESSES ACT TO CLOSE UP SMALL

PORES OR SEPARATIONS AT THE PHASE INTERFACES AND GENERALLY MAKE THE FRACTURE PROPAGATION

1 2 3> frMAKE THE FRACTURE PROPAGATION

PROCESS MORE DIFFICULT

UNIAXIAL TENSILE TESTROLLING & FORGING

OF BILLETS & INGOTSTENSION

TEST

1 2 3>

UNIAXIAL COMPRESSION TEST

-1/3 1/30

m

Kf

EXTRUSION PROCESS PARAMETERS

• INTRINSIC VARIABLES Temperature of extrusion St i t ( t ll d b R d) Strain rate (as controlled by Ram speed) Strain rate sensitivity

• EXTRINSIC VARIABLES Tooling

Inter dependence Of Principal Variables

gTool geometryTool TemperatureM t i l f t lMaterial of tool

Lubrication Heat loss during transportation of billetHeat loss during transportation of billet

3780T HORIZONTAL EXTRUSION PRESS

Extrusion Data Acquisition

OBJECTIVE OF EXTRUSION SIMULATION STUDYSIMULATION STUDY

To carry out the “Design and Control of Experiments to arrive at the optimisedExperiments to arrive at the optimisedparameters of Billet preheat temp, extrusion speed extrusion ratio toolextrusion speed, extrusion ratio, tool geometry etc.”

• Hit-and-Trial Method :• Hit-and-Trial Method : Expensive Time consuming unreliable.

• Computer simulation : Customizable Safe Inexpensive,

METHODOLOGY OF SIMULATION/ PRINCIPLES OF HYPERXTRUDE

Billet cavity, Die Cavity, Land Cavity & Profile.

HEX 8 l t t ti 8 t HEX‐8 element, aspect ratio 8 to avoid non‐convergence.

Elements across any dimension6. 30° Sector , Axi‐symmetric problem.

Structured Arbitrary Lagrangian Eulerian mesh consisting of 37200 to 39600 elements .

30°HyperXtrudehp‐adaptive FE‐based software;

bi CAD l d i li icombines CAD, solver and visualization tools.Extrusion‐specific interface.Inputs finite element mesh materialInputs finite element mesh, material data, boundary conditions & process parameters

CONSTITUTIVE EQUATIONFlow in Extrusion is modeled as Viscous incompressible flowFlow in Extrusion is modeled as Viscous incompressible flow.

Fundamental equations: conservation of mass, momentum and energy· U = 0· U = 0

ρ (U · ) U = · (σ)ρCP U · T = · q + φρCP U T q φ

Where, U is the velocity vector, σ is the total stress tensor, Tis the temperature, ρ is the mass density, CP is the specific heat ofthe fluid at constant pressure, q is the heat flux vector, and φ

The material behavior is specified by the constitutive relations for

p , q , φrepresents internal heat generation rate due to viscous dissipation.

p ythe viscous stress tensor, (τ ) and the heat flux vector (q)

τ = 2µγ;γ = [( U ) + ( U )]T

U is the velocity vector, µ isthe viscosity and k is theγ [( U ) + ( U )]T

q = −k Tthe viscosity, and k is theisotropic thermal conductivityof the material.

APPROXIMATIONS/ASSUMPTIONS

• Constant Ram velocity

• Heat transfer & friction coefficientsoptimization and comparison with p pexperimental ram-force curve

MESHING SCHEME, MODEL COMPONENTS AND BOUNDARY CONDITIONS

Convective heat transfer to container and die, Coulomb friction

Conical Die

Coulomb friction

BilletDieSymmetry

Free Surface

Traction force = 0Convective heat transfer to mandrel, Coulomb

frictionfriction

BOUNDARY CONDITIONS• Convective Heat Transfer boundary: All tool face boundaries areassigned convective heat transfer boundary, i.e., heat removal from thesefaces is through convection.

• Friction Boundary: When shear stress over contact surfaces exceedscritical shear stress, material starts to flow.

I fl B d A t t l it d t t b d• Inflow Boundary: A constant velocity and temperature boundarycondition is assigned at billet ram face.

• Free Surface Boundary: Free surface boundary is assigned at profilesurface. This boundary is assigned an insulated boundary

i.e. q (heat flux) = 0.

• Outflow Boundary: This boundary is assigned to profile face.Outflow Boundary: This boundary is assigned to profile face.Traction forces = 0 (as the extrudate is not pulled out of the die),Displacement 0 (as extrudate is free to expand), Heat Flux = 0

• Symmetric Boundary: This is assigned to symmetric faces.

BOUNDARY CONDITIONS (MATHEMATICAL FORM)(MATHEMATICAL FORM)

Bill t R I t f U U T TBillet-Ram Interface : U = URam ; T = TRam

Billet Container Interface : τ = µσ ; T = TBillet-Container Interface : τS = µσN ; T = TContainer

Die Face : τS = C (U − UTool ) ; T = TContainerS ( Tool ) ; Container

Bearing Surface : τS = C (U − UTool )

Free Surface : σ · n = 0

FLOW BEHAVIOUR DATA FOR ZR-2.5NB ALLOY

Flow Stress (MPa) at Temperature (°C)

ZR 2.5NB ALLOY

StrainStrain

rate (s-1)650 700 750 800 850 900 950

0.001 72.7 50.3 33.5 15.1 13.8 10.9 8.1

0.01 122.3 80.8 61.8 36.5 27.8 18.2 16

0.50.1 143 118.4 75 66.4 44.2 30.2 25.8

1 332.8 180.1 129.7 92.7 60.4 45.7 39.3

10 303.1 234.6 179.6 120.5 88.1 78 70.7

100 286.3 264.1 222.4 151.2 120 100.7 87.3

EXTRUSION PARAMETERS RANGE FOR EXTRUSION SIMULATIONSEXTRUSION SIMULATIONS

• Effect of ram velocity : OD 119 mm, WT 6 mm, billet preheattemperature 815°C, included die angle 90°, fillet radius of 10 mm,

d ti ti 14 44 l iti 1 / 3 / 30 / 47reduction ratio 14.44, ram velocities: 1 mm/s, 3mm/sec, 30 mm/s, 47mm/s, 75 mm/s, 125 mm/s.

• Role of reduction ratio: OD 119 mm, ram velocity 30 mm/s, filletradius of 10 mm, Billet preheat temperature 815°C, included die angle90°, reduction ratios: 6, 8, 10, 12, 14.44, 20.

• Effect of preheat temperature: OD 119 mm, WT 6 mm, ram velocity 30mm/s, included die angle 90°, fillet radius of 10 mm, reduction ratio14.44, billet pre-heat temperatures: 775°C to 855°C at intervals of 10°C.

• Effect of fillet radius: OD 119 mm, WT 6 mm, ram velocity 30 mm/s,yincluded die angle 90°, billet preheat temperature 815°C, reduction ratio14.44, fillet radii: 1 mm, 5 mm, 10 mm, 20 mm.

OPTIMIZATION OF CONVECTIVE HEAT TRANSFER COEFFICIENT (W/m2 .K)

3000 CONSTANT FRICTION COEFFICIENT VALUE OF 0.1

2000

2500

)

1500

2000

Forc

e (T

on)

Conv. 10Conv. 100Conv. 250

1000Ram

F Conv. 500Conv. 750Conv. 1000

0

500DAS_Total Force

00 100 200 300 400 500

Ram Travel (mm)

OPTIMIZATION OF FRICTION COEFFICIENT

2500 CONSTANT HEAT TRANSFERVALUE OF 100 W/m2 K

2000

n)

VALUE OF 100 W/m2 .K

1500

Forc

e (T

on

DAS_Total Force

Friction 0.01

Friction 0 1

500

1000

Ram

F Friction 0.1

Friction 0.5

Friction 0.7

0

500 Friction 0.9

0 100 200 300 400 500

Ram Travel (mm)

OPTIMIZATION OF CONVECTIVE HEAT TRANSFER AND FRICTION COEFFICIENTS

2500

3000

AGREEMENT OF SIMULATED LOAD PROFILES AND EXPERIMENTAL LOAD

2000

2500

ons)

AND EXPERIMENTAL LOADOptimized values: 100 W/m-2 /K and 0.1

1500

Forc

e (T

o

Shop Floor Data

1000

Ram

F

p47mm/s_500W/m-2/K_FrCoef0.0147mm/s_100W/m-2/K_FrCoef0.147mm/s_100W/m-2/K_FrCoef0.947mm/s_50W/m-2/K_FrCoef0.14 / 0 / 2/ C f0 9

50047mm/s_50W/m-2/K_FrCoef0.9

00 50 100 150 200 250 300 350 400

Ram Displacement (mm)

SCHEMATIC GEOMETRY OF EXTRUSION SETUPDETAILS OF THE EXTRUSION MODEL

Billet

Fillet Radius

Tube WT

Length of the billet 450mm

Fillet Radius 10mmBillet OD

TUBE

semi Die Angle Land length 6 mm

Profile length 10mm

225TUBE ID

Billet O.D 225mm

Tube O.D 119 mm

Tube I D 107 mmTube I.D 107 mm

Sector modeled 30°Average no. of elements 38000elements

No. of element layers in Radial direction

15

fNo. of elementlayers along circumferential direction

20

TYPICAL TEMPERATURE CONTOURS

Location of highest

temperature

EFFECT OF RAM VELOCITY ON EXTRSUION LOAD

2300

2500Peak Ram Force

EXTRSUION LOAD

2100

2300

ns)

Steady State Ram Force

1700

1900

Forc

e (To

n

1300

1500

Ram

F

900

1100

9000 20 40 60 80 100 120 140

Ram Velocity (mm/s)

EFFECT OF RAM VELOCITY ON CROSS SECTIONAL TEMPERATURE DISTRIBUTION

960

980LETE 960

980LETEa bRAM VELOCITY RAM VELOCITY

900

920

940

960

atur

e (

C)

TE

900

920

940

atur

e (

C)

TEa bRAM VELOCITY20mm/sec

RAM VELOCITY47mm/sec

820

840

860

880

Tem

pera

820

840

860

880

Tem

pera

20mm/s 47mm/s

800

820

0 1 2 3 4 5 6 7

Distance from ID (mm)

800

820

0 1 2 3 4 5 6 7

Distance from ID (mm)980 LE

980LE

/ 47mm/s

920

940

960

e (

C)

LETE

900

920

940

960

re (

C)

LETEc d RAM VELOCITY

125mm/secRAM VELOCITY

75mm/sec

840

860

880

900

Tem

pera

tur

840

860

880

900Te

mpe

ratu

r

800

820

0 1 2 3 4 5 6 7


800

820

0 1 2 3 4 5 6 7


75mm/s 125mm/s

EFFECT OF LOWER RAM VELOCITY ON LEADING AND TRAILING END TEMPERATURE PROFILES

(AT FILLET REGION)

RAM VELOCITY1mm/sec

RAM VELOCITY3mm/sec

1 mm/s 3 mm/s

2700Peak Ram

EFFECT OF EXTRUSION RATIO ON EXTRUSION LOAD

2300

2500Force


1900

2100

(Ton

s)

1700

1900

m F

orce

(

1300

1500Ram

900

1100

9000 5 10 15 20 25

Reduction Ratio

EXTRUDATE PROFILES AT DIFFERENT REDUCTION RATIOS

EFFECT OF EXTRUSION RATIO ON TEMPERATURE PROFILES BETWEEN LE AND TE OF EXTRUSION

(AT FILLET REGION)(AT FILLET REGION)

980LE 980

LE

900

920

940

960

re (

C)

TE

900

920

940

960

re (

C)

LETERR=6 RR=20

840

860

880

900

Tem

pera

tu

840

860

880

900

Tem

pera

tur

800

820

0 5 10 15 20


800

820

0 1 2 3 4 5


RR = 6 RR = 20

EFFECT OF EXTRUSION RATIO ON TEMPERATURE GRADIENTS ACROSS THE SECTION

200

160

180

200m

m)

RR6

RR20

120

140

ent (

C/m

80

100

e G

radi

e

20

40

60

pera

ture

-20

0

20

Tem

-200 0.2 0.4 0.6 0.8 1

% Wt Away from ID

2900

EFFECT OF PREHEAT TEMPERATURE ONEXTRUSION LOAD

2500

2700

2900 Peak Ram Force


2100

2300

2500

Tons

)

1700

1900

2100

m F

orce

(T

1300

1500

1700

Ram

900

1100

1300

900770 780 790 800 810 820 830 840 850 860

Preheat Temperature (oC)

960

980LETE 960

980LETEa b

EFFECT OF PREHEAT TEMPERATURE ON CROSS SECTIONAL TEMPERATURE DISTRIBUTION

900

920

940

960

ture

(C

)

TE

900

920

940

960

ture

(C

)

TE

820

840

860

880

Tem

pera

t

820

840

860

880

Tem

pera

t

8 °C 80 °C800

820

0 1 2 3 4 5 6 7


800

820

0 1 2 3 4 5 6 7

Distance from ID (mm)980

LE 980LEd

785°C 805°C

900

920

940

960

re (

C)

LETE

920

940

960

re (

C)

LETEc d

840

860

880

900

Tem

pera

tur

840

860

880

900

Tem

pera

tur

800

820

0 1 2 3 4 5 6 7


800

820

0 1 2 3 4 5 6 7


825°C 855°C

2700Peak Ram

EFFECT OF DIE FILLET RADIUS ON RAM FORCE

2300

2500Force


2100

2300

Tons

)

1700

1900

m F

orce

(T

1300

1500Ram

900

1100

9000 5 10 15 20 25

Fillet Radius (mm)

960

980LETE 960

980LETE

a b

EFFECT OF DIE FILLET RADIUS ON CROSS SECTIONALTEMPERATURE DISTRIBUTION

900

920

940

960

ture

(C

)

TE

900

920

940

960

ture

(C

)

TE

820

840

860

880

Tem

pera

t

820

840

860

880

Tem

pera

t

1 5800

820

0 1 2 3 4 5 6 7


800

820

0 1 2 3 4 5 6 7

Distance from ID (mm)980

LE980

LEd

1 mm 5 mm

920

940

960

re (

C)

LETE

920

940

960

re (

C)

LETEc d

840

860

880

900

Tem

pera

tur

840

860

880

900

Tem

pera

tur

800

820

0 1 2 3 4 5 6 7


800

820

0 1 2 3 4 5 6 7


10 mm 20 mm

Zr‐2 5Nb Alloy Pressure TubeZr 2.5Nb Alloy Pressure Tube Produced With Modified Route

Fabrication Routes550 di M lti I t

Forging to

350mm dia Melted Ingot 550 mm dia Melting Ingot

Extrusion to

I stage forging to 350mm diaForging to

230mm diaExtrusion to

230mm diaII stage forging to 230mm dia

quenching(1000C/30min)

Extrusion to119mm OD x 6mm WT(8150 C)

Extrusion to133mm OD x 9mm WT(8000 C)

Ist pilgering to 119mm OD x 6mm WT

( )(8150 C)( )(8000 C)

Stress relieving at 480C/3hStress relieving

at 480C/3hp g g

Final pilgering to 112 8mm OD 103 4mm ID

Annealing (550C/6h)

Final pilgering to 112.8mm OD 103.4mm ID

Autoclaving at 4000C/36 hrs

PROCESS FLOW SHEET FOR Zr‐2.5%NbPRESSURE TUBES FOR 700 MWe PHWR REACTORS

M j P i St A d V i bl

Vacuum Melted Ingots (550mm OD)

Major Processing Stages And Variables Affecting Metallurgical Characteristics

•Forging Temperature

1st Radial forging to 350mm Diameter logs

2nd Radial forging to 230mm Diameter Rods

Forging Temperature•Forging strain rate•Forging pass schedule

Machining, Expansion, Beta quenching, Machining

Bl k E i

•Ram Velocity•Extrusion Ratio•Preheating Temperature

ad a o g g to 30 a ete ods

Blank Extrusion

Vacuum Stress relieving

•Die Profile( Fillet Radius)

Pilgering to final size of 112.8 mm OD X 103.4 mm ID

UT ET Di i l Vi l I ti

• Temperature uniformity in vacuum furnace

• Variation in the cold work UT, ET, Dimensional, Visual Inspection

Autoclaving

CHANGES IN SPECIFICATIONS

CHEMISTRYElement 540 MWe 700 MWe

Nb 2.4‐2.8 % 2.5‐2.8 %

O 900‐1300 ppm 1100‐1400 ppmO 900 1300 ppm 1100 1400 ppm

Fe < 650 ppm (impurity) 900‐1300 ppm (alloying element)

C < 125 ppm (impurity) 40‐80 ppm (alloying element)

Other impurity limits remain same for 540 and 700 MWe pressure tubes

METALLURGICAL PROPERTIES

Description 540 MWe 700 MWe

Other impurity limits remain same for 540 and 700 MWe pressure tubes

Microstructure Radial ~0.3 micron Radial ~0.3 micron

Axial ~ 5‐10 micron Radial : Transverse: Axial ~ 1:5:50

Texture Ft: 0.5 to 0.6 Ft: 0.6 to 0.7Texture

Fr: 0.3 to 0.4 Fr: 0.25 to 0.35

Fl </=0.1 Fl </= 0.1

Other parameters like dislocation density hydride orientation parameters areOther parameters like dislocation density, hydride orientation parameters aresimilar for 540 and 700 MWe pressure tubes

Extruded microstructure formicrostructure for high and low E.R extruded blankextruded blank

Fig. 1 Bright field TEM g gmicrographs of pressure tube blanks extruded with different extrusion ratios; (a) leading end and (b) trailing end ( ) g ( ) g

of tube extruded with ER 7.3:1, (c) leading end and (d) trailing end o

(b) f tube extruded with ER ( )12.75:1.

Final autoclaved microstructure for two stage and single stage pilgered tube

Fig. (a) and (b) SEM micrographs of leading and trailing ends of pressure tube single extrusion-, tube blank extrusion with low ER (7.3:1), double pass pilgering with intermediate annealing followed by autoclaving,(c) and (d) double radial forged- extruded (12.75:1), single pass pilgered,

Final autoclaved microstructure formicrostructure for

two stage and single stagesingle stage pilgered tube

Fig. 3 Bright field TEM micrographs; (a) leading and (b) trailing end of pressure tubemanufactured through double pass pilgering with intermediate annealing, (c) leading and (d)trailing end of pressure tube manufactured through single pass pilgering.

FABRICATION ROUTE &STAGE

LOCATION ASPECT RATIO length thickness

Comparison of Morphology of Alpha grains in Various Routes

Double pilgeredEx P2 Leading 1:4:30 8-10 0.1-0.3

Trailing 1;5:45 6-11 0.1-0.3

F 1 P 2 Leading 1:4:35 5-12 0 2-0 4F 1 P 2 Leading 1:4:35 5-12 0.2-0.4Trailing 1:5:40 8-13 0.1-0.3

F2 P2 Leading 1:4:35 7-14 0.2-0.4Trailing 1;5;45 8-13 0.2-0.45

Si l il dSingle pilgeredEx P1 Leading 1:6:60 10-14 0.2-0.5

Trailing 1:5:50 12-19 0.1-0.4F1P1 Leading 1:6:55 12-18 0.2-0.4

Trailing 1:5:45 14-22 0.1-0.4F2P1 Leading 1:5:50 14-21 0.2-0.5

Trailing 1:5:60 12-20 0.2-0.6F1R2 Leading 1:10:50 20-30 0.5-0.6

Trailing 1:10:55 22-30 0.5-0.55

R1R2 Leading 1:10:65 25-30 0.4-0.5

Trailing 1:10:70 25-32 0.35-0.45

Canadian 1:5:60 10-25 0.2-0.4Note: Double pilger route results in small grain length and width and low A.R.

Double forge route with radial forging show thicker grain, highest AR and large lengthForged route shows uniform structure R1R2 shows best uniformity in microstructure

TEXTURE RESULTS OF AUTOCLAVED PRESSURE TUBES PRODUCED FROM DIFFERENT ROUTES (Leading End)

Fabrication Route and stage FR FT FA FT ‐FRDouble pass pilgered

ExP2 (standard NFC route) 0.33 0.59 0.08 0.25PF1P2 0.34 0.62 0.04 0.28PF12P2 0 38 0 67 0 07 0 29PF12P2 0.38 0.67 0.07 0.29

Single pass pilgered

ExP1 0.27 0.68 0.05 0.40PF1P1 0.27 0.68 0.05 0.42PF12P1 0.27 0.72 0.05 0.45PFIR2P1 0.29 0.68 0.04 0.39R1R2P1 0.26 0.68 0.06 0.42

High FT and High FT-FR values with Single pass pilgering.High FT and High FT FR values with Single pass pilgering.Highly reproducible texture in single pass pilgered tubes. Independent of the primary hot working process.

Texture: Variation between the ends

Fabricate Route FR FT FA FT ‐FR

d 0 29 0 61 0 10 0 32EX1P1

Leading 0.29 0.61 0.10 0.32

Trailing 0.28 0.66 0.06 0.38

PF1P1Leading 0.27 0.68 0.05 0.41

PF1P1Trailing 0.26 0.71 0.03 0.45

PF12P1Leading 0.26 0.69 0.05 0.43

lTrailing 0.25 0.69 0.06 0.44

PF1R2P1Leading 0.27 0.68 0.05 0.41

Trailing 0.26 0.70 0.04 0.44

R1R2P1Leading 0.26 0.68 0.06 0.42

Trailing 0.28 0.68 0.04 0.40

Note: Primary deformation with extrusion shows higher variation in texture

TEXTURE (Autoclaved)

TUBE ENDFr Ft Fl

0.25‐0.35 0.6‐0.7 <0.1

Average# 0.29 0.67 0.05

O 0 29 0 68 0 03O 0.29 0.68 0.03

Std. Deviation

# 0.01 0.02 0.01

O 0.02 0.02 0.01

Maximum# 0.32 0.69 0.07

O 0.32 0.71 0.07

# 0 26 0 62 0 03Minimum

# 0.26 0.62 0.03

O 0.26 0.64 0.02

Mechanical Properties RT at 300C

RoutesRT at 300 C

UTS(KSI)

YS(KSI)

% EL UTS(KSI)

YS(KSI)

% EL

SPECIFICATION (540 MWe PHWR) ‐ <85 ‐ 67 (min) 47 (min) 14 min)

Double pilgeredExP2 (standard NFC route) 111.6 79.8 18.1 78.6 56.9 22.0PF1P2 114.4 81.4 18.0 76.4 57.4 18.0PF1P2 114.4 81.4 18.0 76.4 57.4 18.0PF12P2 (550mm new chem) 112.4 76.5 10.6 75.1 57.3 16.9

Single pilgeredExP1 106 7 78 7 18 0 72 9 61 4 18 4ExP1 106.7 78.7 18.0 72.9 61.4 18.4PF1P1 106.8 76.3 20.0 72.7 54.6 21.3PF12P1(550mm new chem) 119.1 86.0 15.5 80.5 62.8 19.1PF1R2 (550 h )PF1R2 (550mm new chem) 110.0 80.0 14.7 78.7 59.2 20.2R1R2 (550mm new chem) 115.0 89.0 16.0 84.3 62.8 20.7

N R1R2 d F1R2 h i b h dNote: R1R2 and F1R2 showing best strength and ductility values at high temp

High temperature mechanical properties (300C) (averaged) of autoclaved pressure tubes made from

g g( g ) p

double radial forged ingot

ROUTE SAMPLEUTS YS % Elongation

67 KSI (MIN) 47 KSI (MIN) 14

PF1R2 P1LE 78.7 59.2 20.23

TE 81.6 62.8 21.30

R1R2P1LE 84.3 62.8 20.70

TE 85.4 62.3 20.86

Note: Mechanical properties of leading and trailing end are nearly the same

MECHANICAL PROPERTIESMECHANICAL PROPERTIES: : Variation along the length of the pressure Variation along the length of the pressure tubestubes

(RT - YS: 85ksi(max))(HT UTS 68k i( i ) YS 47k i( i ) %El 12% ( i ))

Mechanical Room temperature High temperature (314C)

(HT - UTS: 68ksi(min), YS: 47ksi(min), %El: 12% (min))

properties Leading end Trailing end Leading end Trailing end

UTS (ksi) 102‐118 (115) 106‐118 (113) 70‐78 (84) 68‐80 (85)

YS (ksi) 71‐85 (89) 78‐85 (81) 50‐58 (63) 50‐59 (62)

% Elongation 16‐20 (16) 14‐19 (18) 17‐21 (21) 16‐20 (21)

Data in Red is from the previous trial

Observations: • RT Mech props: trailing end is showing slightly higher strength and lower ductility• HT Mech props: Both ends are showing nearly similar strength and ductility • Last trial mech props are also lying in the same range

Summary

• Grain shape: Both alpha and beta are lamaller and beta phase is Microstructure

continuous

• Grain Morphology: Av. length =40m, width 5m thickness ~0 7m (from SEM measurements) 0 3-0 7 m ( from TEM)0.7m (from SEM measurements) 0.3 0.7 m ( from TEM) Aspect ratio=1:5:50

• No appreciable difference in leading and trailing microstructure.• Tube to tube variation in microstructure was not significant.

Texture• Av. Ft =0.69; Ft-Fr = 0.36 nearly same at both ends. Variability inAv. Ft 0.69; Ft Fr 0.36 nearly same at both ends. Variability in

texture values is very low.

Summary Of TEM Observations

• Alpha and beta grains were lamellar.• Beta was continuousBeta was continuous.• Alpha thickness varying from 0.3 to 0.7 microns• No appreciable difference in leading and trailing• No appreciable difference in leading and trailing

microstructure.• Tube to tube variation in microstructure was not• Tube to tube variation in microstructure was not

significant.

Effect of Ram Velocity:

Summary of Simulation Studies

Effect of Ram Velocity: Lower ram velocities resulted in appreciable temperature loss at

tailing end thus giving rise to more leading end to tailing end variation higher ram velocities were found to increase the variation across theg

thickness. Simulations showed that peak force of extrusion is stronger function

of the ram velocity than the steady state force.

Effect of Reduction Ratio Higher reduction ratios resulted in increasing the temperature

di t th thi k d t i d t i di t t digradients across the thickness due to increased strain gradients at dieprofile side.

Effect Of Preheat TemperatureSimulations indicate that using of higher preheat temperature willSimulations indicate that using of higher preheat temperature willhave beneficial effect in terms of overall homogeneity.

Effect of Die fillet RadiusFrictional heating at the die profile was found to be moreFrictional heating at the die profile was found to be more

substantial than the temperature drop due to mandrel chilling effect.

Th k YThank You

A Study of the Effect Of Extrusion Parameters On the ... · PDF fileA Study of the Effect Of Extrusion Parameters On the Properties Of Extruded Zr-2.5Nb Pressure Tubes N Saibaba Chief

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