How to Make p Wps Din

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APPROVAL TECHNOLOGY FOR ARC WELDING OF St S2-3N STEEL PLATES WIT H...

WELDING PROCEDURE SPECIFICATION FOR ARC W ELDING

OF St 52-3N STEEL PLA TES W ITH COVERED ELECTRODES

S.Cvetkovski, Faculty of Technology and m etallurgy - Skopje

D.

Slavkov, Faculty of Technology and metallurgy - Skopje

J. Magdeski, Faculty of Technology and m etallurgy - Skopje

A bs tra ct : In this paper the results of approval welding technology for arc welding of plates made of St 52-3N steel

are presented. Metal arc welding with covered electrode is used welding process. Test specimens are butt welded in

different welding positions P

A

,PF,Pcand P

D

. Before start welding preliminary welding proced ure was prepared . A fter

welding of test specimens non destructive and destructive testing was performed. Obtained results were compared

with standard DIN 17100 which concerns to chemical composition and mechanical properties of base material. It

was confirmed that in all cases mechanical properties of welded joint are higher than those of base material, so

preliminary welding procedure (pWPS) can be accepted as welding procedure specification WPS for metal arc

welding of St52-3N steel.

INTRODUCTION

Welding is a special process which requires the coordination of welding operation in order to establish

confidence in welding fabrication and reliable performance in service. The tasks and responsibilities of

personnel involved in welding related activities, e.g. planning, executing, supervising and inspection,

should be clearly defined. Welding is considered a special process in the terminology of standards for

quality systems. Standards for quality systems usually require that special processes be carried out in

accordance with written procedure specifications. So welding procedure specifications are needed in order

to provide a well-defined basis for planning of the welding operations and for quality control during

welding. It can be said that Welding procedure (WP) is a specified course of action to be followed in

making a weld, inducing reference to materials, preparation, preheating (if necessary), method and control

of welding and post-weld heat treatment (if relevant), and necessary equipment to be used. But as first

Preliminary welding procedure specification (pWPS) has to be prepared. Preliminary w elding procedure

specification is a tentative welding procedure specification, which is assumed to be adequate by the

manufacturer, but which has not been approved. Welding of test pieces is needed for approval of a

welding procedure specification and has to be carried ou t on the basis of a preliminary w elding p rocedure

specification. If standard requirements are fulfilled, welding procedure specification (WPS) become a

document providing in detail the required variables for a specific application to assure repeatability.

PRELIMINARY WELDING PROCEDURE (pWPS)

The preliminary welding procedure specification was prepared in accordance w ith EN 288-2. It specu

v

tolerance range for all the relevant parameters.

The base material are plates with thickness 30 mm , made of St 52-3N steel. This steel belongs to fir&t

group of steels, according to EN 28 8 as can be seen below:

Steels with a minimum yield strength Re

h

< 360 N/mm

2

and with analysis not exceeding, in %:

c

=

Si =

Mn =

Mo =

C —

p =

Any other single element =

All elements total =

0,24 (0,25 for castings)

0,60

1,70

0,70

0,045

0,045



152 Proceedings of 3

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APPROVAL TECHNOLOGY FOR ARC WELDING OF St 52-3N STEEL PLATES W ITH...

As a welding process metal arc welding process with covered electrode is choosen (111 EN 24063).

Covered electrode EVB 50 intended for welding of carbon and low alloyed steels with yield strength till

610 N/mm

2

is recommended to be used a filler material for welding. Before start with w elding, drying of

electrodes at temperature of 300 °C/2h is recommended.

Welding has to be done in 4 different positions according EN 288 which designation is shown at figure 1.

P

A

flat P

F

vertical upwards P

c

horizontal-vertical P

E

overhead

Figure 1. Welding positions for different specimens (Butt welds)

For those welding positions and thickness of base material, groove preparations like on the figure 2 are

given.

1

n

i

a b

Figure 2 Groove preparation for specimens P

A

,P F and P

G

(a) and P

c

(b)

Recommended preheating temperature is 100 °C (determined by m ethod of Seferian). The edges of

welding plates are grinded before start of welding.

Used welding parameters are given in tables 1-4, and figures 3.

lable

Run

1

2

3

4

5

6

7

1 Number of runs and order of fil ling out the groove for PA welding position

Process

Traveling

Traveling

Traveling

Traveling

Traveling

Traveling

Traveling

Electrode

diameter

EVB50 (t>3.2

EVB50


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APPROVAL TECHNOLOGY

FOR ARC

WELDING

OF St

52-3N STEEL PLATES W ITH...

Table

2

Number

of

runs

and

order

of

filling

out the

groove

for P

F

welding p osition

Run

1

2

3

4

5

6

7

Process

Traveling

Traveling

Traveling

Traveling

Traveling

Traveling

Traveling

Electrode

diameter

EVB50

03.2

EVB50

4

E V B 5 0

(])4

E V B 5 0 4

EVB50 04

EVB50

04

EVB50

04

Current

[A]

110-120

150 -160

150 -160

140 -150

140 -150

140 -150

130 -140

Voltage

[V]

19-20

20-21

20-21

20-21

19-20

19-20

19-20

Type of current / polarity

DC/inverted polarity







Travel

speed

[mm/min]

55-60

70-75

70-75

80-85

75-80

75-80

70-75

Table

3

Number

of

runs

and

order

of

filling

out the

groove

for P

c

welding position

Run

1

2

3 .

4

5

6

7

8

Process

• Traveling

-

Traveling

Traveling

Traveling

Traveling

Traveling

Traveling

Traveling

Electrode

diameter

EVB50

03.2

EVB50 04

EVB50 05

EVB50

04

EVB50 04

EVB50 04

EVB50 04

EVB50 04

Current

[A]

110-120

150 - 170

200-210

200

- 210

160

-170

160

-170

170-180

160

-170

Voltage

[V]

19-20

20-21

22-23

22-23

20-21

20-21

20-21

20-21










Travel

speed

[mm/min]

75-80

120 -125

175

180

165

170

220

225

125

126

125 -130

125-130

Table

4

Number

of

runs

and

order

of

filing

out the

groove

for P

E

welding position

Run

1

2

3

4

5

6

7

Process

Traveling

Traveling

Traveling

Traveling

Traveling

Traveling

Traveling

Electrode

diameter

EVB50 03.2

EVB50, 04

EVB50 05

EVB50

04

EVB50 04

EVB50 04

EVB50 04

Current

[A]

110-120

140

- 150

200

- 210

130

- 140

130

-140

130

-140

120

- 130

Voltage

[V]

18-19

20-21

22-23

19-20

19-20

19-20

19-20









Travel

speed

[mm/min]

70-75

90-95

85-90

70-75

85-90

90-95

6 5 - 7 0

154

Proceedings

of

3

rd

B MC-2003-Ohrid,

R.

Macedonia


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APPROVAL TECHNOLOGY FOR ARC WELDING OF St 52-3N STEEL PLATES WITH...

P F

L

• 41-- -

\

J

m

Pc PE

Figure 3 Num ber of runs and order of filing out the groove for different welding position

WELDING PROCEDURE TEST

Making and testing of test pieces representing the type of welding used in production are in accordance

with EN

288-3.

The welder who undertakes the welding procedure test satisfactorily in accordance with

EN 288-3 is approved for the appropriate range of approval given in the relevant part of E N 287.

Test piece

The welder assembly to which the welding procedure will relate in production shall be represented by

making a standardized test piece or pieces. The test piece for butt welding of steel plates, like in our case,

is in accordance with figure 4. The length of the test piece shall be such as to provide for the appropriate

test specimens as given in Table 1.

Welding of test piece

Preparation and welding of test pieces were carried out in accordance with the pWPS, and under the

general conditions of welding in the production which they shall represent. Standard EN 288-2 defines a

format for the welding procedure specifications for arc welding of metallic materials, which is considered

to fulfill the requirements in current standards for quality systems as regards procedure specifications.

Test pieces for all welding position were prepared. Dimensions of test pieces are like on the picture 4.

a = 3t; minimum value 150 mm b = 6t; minimum value 350 mm

Fig ure 4 - T est piece for a butt weld of plates

Proceedings of 3

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EXAMINATION AND TESTING

The testing includes both nondestructive exam ination (N DE) and d estructive testing which shall be in

accordance with the requirements of Table 5.

Table 5 Exam ination and testing of the test pieces

Test piece

Butt-weld

Type of test

Visual

Radiographic or ultrasonic

Surface crack detection

Transverse tensile test

Transverse bend test

Impact test

Hardness test

Macro-examination

Extent of testing

100%

100%

100%

2 specimens

2 root and 2 face

specimens

2 sets

required

1 specimen

Footnote

—

d

a

-

b

f

c

-

Penetrant testing or m agnetic particle testing. For non-magnetic materials, penetrant testing.

2 root and 2 face bend test specimens may preferably be substituted by 4 side bend test specimens for / > 12 mm.

c

Not required for parent metals:

- ferrtic steels with R

m

430 N/mm

(R* 275 N/mm

2

);

- group 9 steels.

R« is defined in the relevant product standard.

Ultrasonic testing is only applicab le for ferritic steels and. for t > 8 mm.

Testing as detailed does not p rovide information on the mechanical properties of the joint. Where these properties are relevant to the

application an additional approval shall also be held e.g. a butt weld approval.

One set in the weld metal and one set in the HAZ . Required only for t > 12 mm and only for parent metals having specified impact

properties or when required by the application standard. If a testing temperature has not been specified, testing shall be performed at

room temperature.

NON DESTRUCTIVE TESTS

Visual control and radiographic testing were carried out to all test specimens. Unalowed defects were no

detected. The root and the face of welded joints are w ith regular shape.

DESTRUCTIVE TESTS

Machining probes for destructive testing from test specimens is given in figure 5.

Specimens and testing for transverse tensile testing for butt joint are in accordance with ISO 4136. One

probe for each specimen (welding position is used). Comparing obtained results (Table 6), and the values

for mechanical properties according to DIN 17100 standard (R^ = 345; R

m

= 490-r630; A

5

(%) = 22t, 201),

it can be seen that obtained results are in all cases higher than the values for base material.

1

I

~- Gitcans 2s -va

i

E

A-M 2

tr

- - HMK t*C tHSif«ar l

Figure 5 Machining probes of test specimens for a butt weld in plate

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APPROVAL T E C H N O L O G Y F O R ARC W E LD I N G O F St 52 3 N S T E E L P L AT E S W I T H . ..

Table 6 Results of transverse tensile testing of test specimen s for different welding positions

Specimen

PΑ

P F

P c

P E

R eh

[ N / r a m

2

]

366

365

364

369

Rm

[ N / m m

2

]

515

520

519

523

A

s

[ ]

26.1

25.2

26.0

25.8

Specimens and testing for bend testing for butt joints shall be in accordance with EN 910. The bending

angle should be minimum of 120°, and in our tests angle of 180° were obtained. Two probes were

prepared from each test specimen. As can be seen from Table 7 all results are allowed.

Table

7

Result

of

bending test

Specimen

PΑ

P F

P c

P E

Bending 18 °

allowed

allowed

allowed

allowed

Test specimens and testing for impact tests for butt joints are in accordance with EN 2883 for position of

specimens and temperature of testing, and with EN 875 for dimensions and testing. Testing of base metal,

welds and HAZ was performed. Machining probes for impact testing is shown in figure 6. Test

temperature was 20 °C. Minimum value for impact energy, according Din 17100 is 27 J. It can be seen

from Table 8, that all results are much higher than this value. Significant differences between obtained

results can be explained by heterogeneity of microstructure, because welding was performed with many

runs .

I N o t c h

o l c i

F i g u r e 6 M achining probes for impac t testing of welded joints

Proceedings of 3

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APPROVAL TECHNOLOGY FOR ARC WELDING OF St 52 3N STEEL PLATES WITH.

Table 8 Results of impact testing of test specimens

S p e c i m e n

P Α

P F

Pc

P D

B a s e m e t a l

1 4

85

96

89

7

7

1 1

1

2

86

8

63

Z

97

97

71

46

52

158

147

15

53

154

25

137

el

6

174

56

5

12

2

32

147

53

141

137

63

T h e

method of hardness testing shall be in accordance with EN 1043. The

Vickers

method HV10 was

used. The indentation was made in the weld, the HAZs and the base metal. Maximum hardness values

allowed with standard for this group of steel is 380 HV10 (without heat treatment).

Measured hardness values on test specimens are following:

Weld:

159 179 HV10

H A Z : 159 183HV10

Base metal 136 140 HV10

Those values are much lower from the values

given

in standard, and confirmed good welding parameters.

Metallographic testing

T h e test specimen for macro examination was prepared and etched on one side in accordance with

E N

1321, to clearly reveal the fusion line, the HAZ and the build up of the runs. Unallowed defect were

n o detected. Detailed microstructural examination was carried out to detect characteristic

microconstituents in welded joints, figure 7 a e ) . Microstructure of weld metal (fig 7a) consists of

proeutectoide ferrite which forms at higher transformation temperatures, at the boundaries of primary

austenite grains. Inside the grains, acicular ferrite is formed. This microconstituent enables high tensile

properties and

very

good impact toughness. Microstructure of coarse grained HAZ consists of ferrite and

bainite and generally has worsened properties, especially impact toughness (7b). The best mechanical

properties has fine grained HAZ which consists of equiaxed bainiticferrite grains, figure 7c. Intercritically

H A Z formed as results of non complete y/ a transformation is shown at figure 7d. It could have worsened

properties as a result of martensite forming during subsequent cooling. Striped ferritepearlite

microstructure is presented at figure 7e.

58

Proceedings of

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APPROVAL TECHNOLOGY FOR ARC WELDING OF St 52-3N STEEL PLATES WITH...

a

*V

^

1

5 ? ^ ^ .

1

- «

• e

Figure 7(a-e) Microstructure of test specimen PA, x500 a. weld metal b. coarse grained HAZ c. fine grained HAZ d.

Intercritically HAZ e. base metal

CONCLUSIONS

Basic idea of this paper was preparing of welding technology for steel plates made of St 52-3N in

accordance with EN 288 standard.

Concerning that, preliminary welding specification was written following standard requirements.

Test specimens for butt welds in positions P

A

, P

F>

P

c

and P

D

were prepared and welded according

preliminary welding procedure specification.

Non destructive and destructive tests were carried out to test specimens. Radiographic and visual

inspection didn't reveal presence of any significant imperfections. Results of mechanical properties of

welded joint were compared with requirements of DIN 17100 standard, for base material.. It was

confirmed that test results are higher than standard's requirements.

So, preliminary welding specification, become approved welding procedure for metal arc welding of steel

plates,

made of St 52-3N plates.

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Literature:

1.

EN 287-1 Approval testing of welders - Fusion welding - Part 1 - Steels;

2.

EN 288-1 Specifications and approval of welding procedure for metallic m aterials - Part 1 - General

rules for fusion welding;

3. EN 288-2 Specification and approval of welding procedure for metallic material - part 2 Welding

procedure specification for arc welding;

4.

EN 288-3 Specification and approval of welding procedure for metallic material - part 3 Welding

procedure tests for the arc welding of steels;

5. EN 1043 Welded joints in metallic materials - Hardness testing;

6. EN 910 Welded butt joints in metallic materials - Bend tests;

7.

EN 895 Welded butt joints in m etallic materials - Transverse tensile tests;

8. EN 875 Welded butt joints in metallic materials - Specimen, location and notch orientation for impact

test;

9. EN 26620 Classification of imperfections in metallic fusion welds, with explanations;

10. ISO 1106-1 Recommended practice for radiographic examination of fusion welded joints -Part 1

Fusion welded butt joints in steel up to 50 mm thick;

11.

ISO 4063 W elding brazing and soldering processes and braze welding of metals - Nom enclature of

processes and reference n umbers for symbolic presentation on drawings;

12.

ISO 6947 Welds - Working positions - Definitions of angles slope and rotations.

160 Proceedings of 3

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BMC-2003-Ohrid, R. M acedonia

How to Make p Wps Din

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