research article specimen test of large-heat-input fusion

Research ArticleSpecimen Test of Large-Heat-Input Fusion Welding Method forUse of SM570TMCP

Dongkyu Lee1 and Soomi Shin2

1Department of Architectural Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747, Republic of Korea2Research Institute of Industrial Technology, Pusan National University, Jangjeon-dong, Gumjeong-gu,Busan 609-735, Republic of Korea

Correspondence should be addressed to Soomi Shin; [email protected]

Received 4 December 2014; Revised 4 January 2015; Accepted 5 January 2015

Academic Editor: Min Wang

Copyright © 2015 D. Lee and S. Shin. This is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

In this research, the large-heat-input welding conditions optimized to use the rear plate and the high-performance steel ofSM570TMCP, a new kind of steel suitable for the requirements of prospective customers, are proposed. The goal of this researchis to contribute to securing the welding fabrication optimized to use the high-strength steel and rear steel plates in the field ofconstruction industry in the future. This research is judged to contribute to securing the welding fabrication optimized to use thehigh-strength steel and rear steel plates in the field of construction industry in the future.

1. Introduction

Since the rigidity and strength required formembers increaseaccording to recent trends of the large space and high risesuch as diagrid [1–4] of architectural structures and the largespan of steel bridges, steel materials gradually tend to aim athigh strength, extremely thick plate, and high performance,and its application is introduced by Schroeter andLehnert [5].Such steel materials, while structured, require mutual con-nection betweenmembers and inevitably accompanyweldingduring the work. Thus, in order to secure the safety ofstructures and the efficiency of work, it is essential to improvewelding quality and secure reliability.

According to the questionnaire survey conducted byKorea Research on the basis of a contract with POSCOand Research Institute of Industrial Science and Technology(RIST) regarding the demand analysis of high-performancesteel types [6] targeting over 500 experts from academia,structural designers, and construction companies, most ofthe experts preferred, as performance standards of high-performance steel kinds, (i) a high design standard strength;(ii) no reduction in the design standard strength in the over40mm thickness; and (iii) excellent weldability. Out of thesepreferences, the first and second preferences are fundamentalrequirements which may cause troubles in securing the

expected performance of steel kinds, while the third onemay be regarded as a secondary requirement which can bepreferentially improved on the basis of the weldability data ofexisting general steels.

In response to such requirements, POSCO has developedPILAC-BT45 steel in 2004, which is denoted as SM570TMC,a 600MPa-class new steel material, for application to archi-tectural structures, whose weldability is improved by reduc-ing the carbon equivalent a great deal, while raising the designstandard strength of steel materials, with the thermomechan-ically controlled (TMC) process. As representative researchesrelated to SM570TMC, Chang et al. [7] introduced experi-mental and numerical investigations on residual stresses ofSM570TMC. Lee et al. [8] provided characteristics of hightemperature tensile properties and residual stresses in weldedjoints.

In general, for high strength and extremely thick steelmaterials, alloying elements are added, which accompaniesthe quality nonuniformity of steel materials. In the weldingwork of using such steel materials, the reduction in thewelding constructability and the structural performance ofwelded areas has been known to be inevitable. Lately, in caseof fabricating steel structures, the application of such a large-heat-input welding method for which Kojima et al. [9]developed high HAZ toughness steel plates of box columns,

Hindawi Publishing CorporationAdvances in Materials Science and EngineeringVolume 2015, Article ID 264798, 13 pageshttp://dx.doi.org/10.1155/2015/264798

2 Advances in Materials Science and Engineering

SAW, FCAW

t

A

A-A section

AWS D 1.1 and KS code

A

SM490TMC (t = 40mm, 80mm)

200mm 20mm

410mm

800

mm

SM570TMC (t = 40mm, 80mm and 100mm)

Figure 1: Welding test steel plate before being cut.

as SAW, has increased to improve the productivity. In case ofapplying steel types of high strength and extremely thick plateunder increasing demand, the verification of such weldabilityis always essential.The rear plate is mostly used as a structureassembled by cutting and welding and so its weldabilityshould sufficiently be considered. In addition, in case ofwelding at low temperatures, the weldingmethod should alsobe reviewed.Meanwhile, though the large-heat-inputweldingmethod has an advantage that it improves work efficiency,the amount of heat input, groove shape, and welding methodshould be sufficiently reviewed in selecting large-heat-inputsteel materials.

In this research, experiments were conducted by takingthe amount of heat input, including the numerical value spec-ified for the rear plate by the fabricator, and the kind of steel(SM490TMC, SM570TMC) as variables and applying theweldingmethods of ESW, SAW, and FCAW, inwhichKou [10]dealt with fusion welding processes of steel, Schwartz [11]described metal joining manual in advance, and Song et al.[12] introduced single-side resistance spot welding as abasis of welding methods, and the large-heat-input weldingconditions are presented in accordancewith the experimentalresults. SM570TMC as newly high strength steel is alternativewhich is the most appropriate to build mega steel structures,as it may save material quantity such as reduction of steelthickness. For the purpose, it is necessary to execute large-heat-input welding, but there is rarely detailed informationof the welding condition of SM570TMC.

In this research, in order to present the optimumlarge-heat-input welding conditions of SM570TMC high-performance steel, the following sequential verification pro-cesses were performed in comparison with the existing char-acteristics of SM490TMC: cutting inspection of steel mate-rials, review of existing welding conditions, amount of heatinput for SAW and FCAW, establishment and verification oflarge-heat-input welding conditions through tensile, flexural,impact, macro, and hardness performance experiments, andpreparation of large-heat-input welding manual.

2. Fabrication of Large Heat InputTest Specimen

2.1. Fabrication of Welding Specimen for SAW and FCAWWelding Test. Thick steel plates are basically used as the steelplates for large-heat-input welding test specimen for SAWand FCAW [13].The thicknesses of SM490TMCP 40mm and80mm and SM570TMCP steels are 40mm, 80mm, and100mm, respectively. Forwelding parts, singleVGroove, rootopening 10mm, root face 0, and angle 30∘ are applied. For pre-heating [14], normal temperature is applied to specimen withthickness below 50mm, and temperature above 50∘C isapplied to thickness 100mm, respectively. Welding test steelplates, shapes of welding specimen, and specification of spec-imen are in accordance with AWS D 1.1 and KS D 3503 code[15], and these are shown in Figures 1 and 2, respectively.

2.2. Fabrication of ESWWelding Specimen. Thick steel platesare basically used as the steel plates for large-heat-input weld-ing test specimen for ESW. The thicknesses of SM490TMCPand SM570TMCP steels are 35mm.Welding parts details arein accordance with AWS D 1.1 and KS code, which are shownin Figure 3.

For ESW, a CES weldingmachine as shown in Figure 4(a)is used, and its status of attachment before welding and afterwelding are shown in Figures 4(b) and 4(c).

3. Experimental Results of Large-Heat-InputWelding Specimen

3.1. Large-Heat-Input Welding Test Details and Test Set-UpProcedures. As a consideration during planning of large-heat-input welding, it is necessary to confirm the weldablethickness in case of ESW [16, 17]. For the case of TAG Com-pany of Japan, in case of using two nozzles, a weldable thick-ness of 100mm has been reported to be feasible. In Korea,the optimumweldable thickness of CESwelder [18] is 60mm,the limit of quality assurance. In this research, the thicknessof parent materials is based on 35mm.

Advances in Materials Science and Engineering 3

Impact test (WM)

Bending test

Tensile test

Rolling direction

Tensile test

Impact test (FL)

1-2W1-1W

1-1F1-2F1-3F

1-3W

1-1

1-1

1-21-31-4

Macro/hardness test

410mm

Impact test (FL + 2mm)

800

mm

1-1F21-2F21-3F2

1-0

1-2

These edges may be the thermally cutThis surface machined preferably B

T

6mm

6mm

T

T

t

W

W C

2

250mm

25mm Rmin.

6mm min. (TYP)

<25mm

Weld face

width

150mm10mm min.

10mm min.

20mm min.

See note 2

3mm R max.

10 ± 0.05

10±0.05

8±0.05

45∘± 2

∘

55 ± 0.6

27.5 ± 0.0427.5 ± 0.04

min.

R0.25 ± 0.025

≥25mm38 = 0.3mm25 = 0.3mm

Figure 2: Welding specimen collection drawing and their shape.

FCAW

ESW

FCAW joint details:

Single bevel, backing bar

Angle = 45∘

Position = 1G

Preheating = 25∘C

SM490TMC (t = 35mm)SM570TMC (t = 35mm)

25mm

50

mm

35t

35t32 ∗ 50mm

Root face = 0

Root gap = 7

Filler metal = supercored 81-k2

Max. interpass temp. = 250

Figure 3: Welding test steel plate before being cut.


(a) CES welding machine (b) Status of attachment before welding

(c) Status of attachment after welding

Figure 4: ESW welding status.

Table 1: Large-heat-input welding test conditions.

Welding process Amount of weldingheat input Welding materials Thickness of parent

materialDetails of welded areasand welding posture

(i) Consider thewelding methodsused mainly infabricating themembers and joints ofarchitecturalstructures.ex) Large-heat-inputwelding: SAW, FCAW,ESW

(i) Fix current andvoltage.(ii) Control theamount of weldingheat input by varyingthe welding speed.

(i) Depending on thechemical composition ofwelding materials,affected are thedeposited metal bylarge-heat-input weldingand the embrittlement ofHAZ part.(ii) Consider theapplication to weldingrod products.

(i) In general, the thickerthe base materials get,cracks may be createddue to the increase in thedegree of constraints forwelded areas and thecontraction stress.(ii) Apply to 35mm,40mm, 80mm, and100mm rear plates.

(i) AWS D 1.1. Applystandard welding detailsto V/dam welding(35mm, 40mm) andX-type groove welding(80mm, 100mm)examined in advance inthe standardspecifications ofarchitecturalconstruction.(ii) The welding postureis 1 G.

The conditions of large-heat-input welding tests estab-lished on the basis of the above contents in this research aregiven in Table 1.

Large-heat-input welding test according to AWSD 1.1 [19]includes visual inspection,NDE, cutting inspection, sectionaltensile test, side face bending test, impact test, and macroand hardness test. Test types carried out in this study aresummarized in Table 2.

Tables 3 and 4 show the specimens for large-heat-inputwelding of SM490TMCP and SM570TMCPwhich are carriedout in this study.

3.2. Tensile Test Results. The results for tensile tests of large-heat-input welding for SM490TMCP and SM570TMCP areshown in Tables 5 and 6, respectively. In case of ESW,

SM570TMCP requires 1.5 to 2 times the amount of heat inputof SM570TMCP and has shown satisfactory yield strength.The elongation at break of SM570TMCP, high strength steel,is found to be about 25, lower than that of SM490TMCP 33,a general steel type.

It has been found that, in case of SAW, an automatic weld-ing, at the same amount of heat input of 50 or 70KJ/cm, asthe plate thickness of SM490TMCP increases from 40mm to80mm, the tensile strength falls from about 550 to about 520.It has also been found that, at the same amount of heat inputof 70KJ/cm, as the plate thickness of SM570TMCP increasesfrom 40mm to 80mm, the tensile strength falls from about660 to about 620.Therefore, in case of SAW, it is judged that asthe thickness increases, it is necessary to increase the amountof heat input from 70 to about 100 in the aspect of securingthe safety of welded areas.


Table2:Testtypeso

flarge-heat-inp

utweld

ing.

Testitem

Testmetho

dSpecim

enQuantity

Judg

mentcriteria

Visualinspectio

nVisual

—Goo

dbead

appearance

onsurfa

ce/noun

dercut

nor

blow

hole

Non

destructivee

xamination

UT

—Th

ereisn

ointernalcrack(hightemperature

crackand

lowtemperature

crack)

onweld

edmetalandHAZpart,

impu

rity,no

rdisc

ontin

uity

Cutting

inspectio

nArchitectural

worksta

ndard

specificatio

n1

(i)Ro

ughn

esso

ncutsurface:refer

to4.2

(ii)C

utdeform

ation:

referto4.3

Sectionaltensiletest

KSB0833

2Tensile

strengthwill

beabovethe

specified

valueo

fbase

metal.

Side

face

bend

ingtest

KSB0832

4Cr

ackedleng

thon

weld

edpartwhenbent

in180∘

will

bebelowthev

alue

requ

iredby

KSB0832.

Impacttest(0,−

5,−20∘

C)Heataffected

part(H

AZ)

KSB0810

3Th

evalue

ofweldedmetalwill

beabovethe

specified

valueo

fbasem

etal.

Weld

edmetalpart(W

M)

3Targetste

eltype

Testtemp.

Criteria

Weld

metalpartFL

3SM

490T

MC

0∘C

27Jo

rabo

veSM

570T

MC

−5∘C

47Jo

rabo

ve

Macro/hardn

esstest

—1

Thereisn

ocrackno

rdeficiency

onweldedmetalpart

andHAZpart.H

ardn

esso

nweldedmetalpartand

HAZpartwill

beabovethe

valuer

equiredby

KS/architecturalworkstandard

specificatio

n.


Table3:Large-heat-in

putw

elding

testdetails

andspecim

ens(SM

490T

MCP

).

Steeltype

Plate

thickn

ess

(mm)

Preheattem

.(∘ C

)Interla

yer

tem.(∘

C)Weld

ing

metho

dInpu

theat

(kJ/c

m)

Voltage

(V)

Current(A)

Speed

(Cm/m

in)

Weld

ingmaterials

SM490

TMCP

35Non

eNon

eES

W61

40±5

380±10

15KD

-50

Non

eNon

e56

45±5

380±10

18KD

-50

40

Non

eMax.250∘

C

SAW

50DC

DC

Weld

ing

rod

Flux

1st:

22∼30

2nd:

26∼34

3rd:

28∼36

1st:

510∼

540

2nd:

580∼

640

3rd:

560∼

620

1st:

22∼30

2nd:

34∼42

3rd:

36∼40

Korea

KD60

EF260

Non

eMax.250∘

C70

Samefor

SAW

Non

eMax.250∘

CFC

AW50

1st:

20∼26

2nd:

26∼34

3rd:

22∼30

1st:

138∼

155

2nd:

180∼

220

3rd:

160∼

200

1st:

6∼12

2nd:

10∼18

3rd:

12∼20

Hyund

aiSupercored

81-k2

8050∘

CMax.250∘

CSA

W50

Samefor

SAW

50∘

CMax.250∘

C70

Samefor

SAW

50∘

CMax.250∘

CFC

AWDangjin

(50)

Samefor

FCAW

Hyund

aiSupercored

81-k2


Table4:Large-heat-in

putw

elding

testdetails

andspecim

ens(SM

570T

MCP

).

Steeltype

Plate

thickn

ess

(mm)

Preheattem

.(∘ C

)Interla

yer

tem.(∘

C)Weld

ing

metho

dInpu

theat

(kJ/c

m)

Voltage

(V)

Current(A)

Speed

(Cm/m

in)

Weld

ingmaterials

SM570

TMCP

35Non

eNon

eES

W80

45±5

390±10

12KD

-60

Non

eNon

e120

50±5

400±10

11KD

-60

40

50∘

CMax.250∘

C

SAW

70

DC

DC

Weld

ing

rod

Flux

1st:

1st:

1st:

Korea

KD60

EF260

22∼30

660∼

740

60∼67

2nd:

2nd:

2nd:

Hyund

aiA-

3S800MX

26∼36

760∼

840

66∼78

3rd:

3rd:

3rd:

28∼34

760∼

860

64∼76

50∘

CMax.250∘

C100

Samefor

SAW

50∘

CMax.250∘

CFC

AW60

1st:

1st:

1st:

20∼28

148∼

154

7∼12

2nd:

2nd:

2nd:

Hyund

aisupercored

81-k2

24∼32

160∼

260

16∼22

3rd:

3rd:

3rd:

22∼30

158∼

240

14∼20

8050∘

CMax.250∘

CSA

W70

Samefor

SAW

50∘

CMax.250∘

CFC

AW60

Sameincase

ofFC

AWweld

ing

100

50∘

CMax.250∘

CSA

W70

Samefor

SAW

50∘

CMax.250∘

CFC

AW60

Sameincase

ofFC

AWweld

ing


Table 5: Results of tensile test in large-heat-input welding test (SM490TMCP).

Steel typePlatethickness(mm)

Preheattem. (∘C)

Interlayertem. (∘C)

Weldingmethod

Input heat(kJ/cm)

Yieldstrength(0.2%,MPa)

Tensilestrength(MPa)

Elongation(%) Fracture part

SM490TMC

35 None None ESW

61 354354

558532

33.432.7

Weld MetalBase Metal

56 342352

518563

31.735.5

Weld MetalWeld Metal

40 None Max.250∘C

SAW

50 411404

557557

27.531.3

Base MetalBase Metal

70 355405

555561

29.931.4


FCAW50 419

416553574

21.323.0

Base MetalWeld Metal

80 50∘C Max.250∘C

SAW

50 339336

523513

34.235.8


70 342355

519529

34.235.8


FCAW 50 348344

528527

28.130.0


Table 6: Results of tensile test in large-heat-input welding test (SM570TMCP).

Steel typePlatethickness(mm)

Preheattem. (∘C)

Interlayertem. (∘C)

Weldingmethod

Input heat(kJ/cm)

Yieldstrength(0.2%,MPa)

Tensilestrength(MPa)

Elongation(%) Fracture part

SM570TMC

35 None None ESW

80 445460

610624

25.226.5


120 456466

616625

22.424.5


40 50∘C Max.250∘C

SAW

70 579583

660655

22.624.2


100 567530

652648

19.322.7


FCAW 60 535531

606407

19.115.9


80 50∘C Max.250∘C

SAW 70 452455

611627

29.834.0


FCAW 60 532529

604589

25.529.7


100 50∘C Max.250∘C

SAW 70 554561

627639

23.336.0

Weld MetalBase Metal

FCAW 60 499502

597596

22.722.5


In case of FCAW, a semiautomatic welding, bothSM490TMCP and SM570TMCP show the tensile strengthwithout deviations regardless of the plate thickness, demon-strating the performance stability for welding fabrication ofspecimens. And, in all cases, breakups occurred at the baseor welded areas.

Figure 5 shows the tensile test result of SAW and FCAWfor SM570TMCP with the thickness of 80mm and 100mm.As can be seen, all tensile test specimens collapse at the weld-ing part, not the parent metal part, after making plastic hingebehaviors. It verifies the superiority of welding connections.

3.3. Side Face Bending Test Results. According to varyinginput heat and thickness, side face bending test results ofSM490TMCPand SM570TMCPare shown in Figure 6.Theseresults are satisfactory in general; however, welding defectsare found in SM490TMCP-40mm-SAW input heat 70 and itshows manufacturing defect of the specimen.

As can be seen in Figures 6(a), 6(d), and 6(f), large heatinput of 70 can be used for the thick and high strengthSM570TMCP specimen of SAW, but SM490TMCP of SAWmay produce welding error owing to too large heat input andrelatively thin specimen condition.


(a) SM570TMCP-80mm-SAW (b) SM570TMCP-80mm-FCAW

(c) SM570TMCP-100mm-SAW (d) SM570TMCP-100mm-FCAW

Figure 5: Tensile test result of SAW and FCAW for SM570TMCP 80mm and 100mm.

(a) SM570-80mm-SAW input heat 70 (b) SM490-35mm-ESW input heat 60 (c) SM570-35mm-ESW input heat 80

(d) SM490-40mm-SAW input heat 70 (e) SM490-80mm-FCAW input heat 50 (f) SM490-40mm-SAW input heat 70

Figure 6: Side face bending test result of SM490TMCP and SM570TMCP.

Notch location (mm)

350

300

250

200

150

100

50

0

W.M HZ F.L

CVN

impa

ct en

ergy

at−5∘C

(J)

Spec. �E −5∘C ≥ 47 J

40t—70kJ/cm 80t—70kJ/cm100t—70kJ/cm40t—100 kJ/cm

(a) SAW

Notch location (mm)

350

300

250

200

150

100

50

0

W.M HZ F.L

CVN

impa

ct en

ergy

at−5∘C

(J)

40t—70kJ/cm80t—70kJ/cm

100t—70kJ/cm

Spec. �E −5∘C ≥ 47 J

(b) FCAW

Figure 7: Impact test result of SM570TMCP welding part.


Notch location (mm)

350

300

250

200

150

100

50

0

W.M HZ F.L

CVN

impa

ct en

ergy

at−5∘C

(J)

35t—80kJ/cm35t—120 kJ/cm

Spec. �E −5∘C ≥ 47 J

(a) SM570TMCP of ESW

Notch location (mm)

350

300

250

200

150

100

50

0

W.M HZ F.L

CVN

impa

ct en

ergy

at−5∘C

(J)

Spec. �E −5∘C ≥ 47 J

35t—61kJ/cm35t—56kJ/cm

(b) SM490TMCP of ESW

Figure 8: Impact test result of SM570TMCP and SM490TMCP welding part.

(a) SM570TMCP-40mm-SAW (b) SM570TMCP-40mm-FCAW

Figure 9: Impact test result of SAW and FCAW for SM570TMCP 40mm.

SM570TMC ESW (120 kJ/cm) SM490TMC ESW (56kJ/cm)

Figure 10: Macro test result of ESW welding for SM490TMCP and SM570TMCP.

3.4. Impact Test Results. Charpy impact characteristics ofwelding parts of weld metal (WM), hard zone (HZ), andfusion line (FL), in case SM570TMCP for both SAW andFCAW meet the requirements in the standards of the reddash line, which are shown in Figure 7. As can be seen,SM570TMCP with thickness of 100mm also produces largeimpact energy at WM, HZ, and FL.

Figure 8 shows impact energies of SM570TMCP andSM490TMCP of ESW at WM, HZ, and PL. As can be seen,impact energies of WM and HZ of the red circle line are notsatisfactory to the standards. It can be found that weldingconditions such as heat input, in especial, for ESW should becontrolled to take manufacturing quality, regardless of steeltype.


100

150

200

250

300

0 5 10 15 20Distance (mm)

HAZ WMBMVick

ers h

ardn

ess (

H�,98.07

N)

(a) SM570-40mm-SAW (70 kJ/cm)

100

150

200

250

300


HAZ WMBMVick

ers h

ardn

ess (

H�,98.07

N)

(b) SM570-40mm-SAW (100 kJ/cm)

100

150

200

250

300


HAZ WMBMVick

ers h

ardn

ess (

H�,98.07

N)

(c) SM570-80mm-SAW (70 kJ/cm)

100

150

200

250

300


HAZ WMBMVick

ers h

ardn

ess (

H�,98.07

N)

(d) SM570-100mm-SAW (70 kJ/cm)

100

150

200

250

300


HAZ WMBMVick

ers h

ardn

ess (

H�,98.07

N)

(e) SM570-40mm-FCAW (60 kJ/cm)

100

150

200

250

300


HAZ WMBMVick

ers h

ardn

ess (

H�,98.07

N)

(f) SM570-80mm-FCAW (60 kJ/cm)

100

150

200

250

300


HAZ WMBMVick

ers h

ardn

ess (

H�,98.07

N)

(g) SM570-100mm-FCAW (60 kJ/cm)

100

150

200

250

300


HAZ WMBMVick

ers h

ardn

ess (

H�,98.07

N)

(h) SM570-35mm-ESW (60 kJ/cm)

Figure 11: Continued.


100

150

200

250

300


HAZ WMBMVick

ers h

ardn

ess (

H�,98.07

N)

(i) SM490-40mm-SAW (50 kJ/cm)

100

150

200

250

300


HAZ WMBMVick

ers h

ardn

ess (

H�,98.07

N)

(j) SM490-40mm-SAW (70 kJ/cm)

100

150

200

250

300


HAZ WMBMVick

ers h

ardn

ess (

H�,98.07

N)

(k) SM490-80mm-SAW (50 kJ/cm)

100

150

200

250

300


HAZ WMBMVick

ers h

ardn

ess (

H�,98.07

N)

(l) SM490-80mm-SAW (70 kJ/cm)

100

150

200

250

300


HAZ WMBMVick

ers h

ardn

ess (

H�,98.07

N)

(m) SM490-40mm-FCAW (50 kJ/cm)

100

150

200

250

300


HAZ WMBMVick

ers h

ardn

ess (

H�,98.07

N)

(n) SM490-80mm-FCAW (50 kJ/cm)

Figure 11: Hardness test results of SAW, FCAW, and ESW welding for SM490TMCP and SM570TMCP.

Figure 9 shows the impact test result of SM570TMCPspecimen. Requested requirements by the standard are thosefor SM490TMCP 27 J and, SM570TMCP 47 J.

3.5. Results for Macro and Hardness Tests. The cross sectionsof specimens for macro test results of ESW welding forSM490TMCP and SM570TMCP, to which heat inputamounts (kJ/cm) of 56 and 120, respectively, were applied,are shown in Figure 10.

Figure 11 shows the results for hardness distribution ofthe base metal (BM), HAZ, and welded metal (WM) areasduring SAW, FCAW, and ESW welding of SM490TMCP andSM570TMCP. As shown in Figure 11, in case the amounts ofheat input for SM570TMCP and SM490TMCP are large, theupper limit of hardness for HAZ part turned out to be large,and in case the amount of heat input are the same, the thickerthe plate, the larger the calculated hardness value. It is naturalto obtain these results, which means that the provided weld-ing conditions are appropriate overall, demonstrating thatthe welding fabrication by SAW, FCAW, and ESW is excellent.


4. Conclusions and Remarks

In this research, embodied are the proper welding conditionsof large-heat-input welding as an efficient welding methodfor performance improvement required for high strength andhigh performance of architectural steel materials. Weldingfabrication tests were conducted for SM490TMCP, a steelkind which is in general used a lot, and SM570TMCP, highstrength steel. An optimum amount of heat input, especially,was quantitatively analyzed for the case of rear plates withhigh strength properties.

In this research, conducted was the performance evalu-ation of the welded areas based on the welding fabricationmethods of SAW, FCAW, and ESW, and proposed are thelarge-heat-input welding conditions optimized to use the rearplates andhigh performance steel of SM570TMCP, a new steelkind suitable for the requirements of prospective customers.

In especial, welding conditions such as heat input forESW including SAW and FCAWhave to be controlled to takemanufacturing quality, regardless of steel type. Large-heat-input condition can be appropriately used for the thick andhigh strength SM570TMCP steel construction, but normalstrength steel such as SM490TMCP may produce weldingerror owing to too large heat input and relatively thinthickness condition.

This research is judged to contribute to securing the weld-ing fabrication optimized to use the high strength steel andrear steel plates in the field of construction industry in thefuture.

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper.

Acknowledgments

This research was supported by the MKE (The Ministryof Knowledge Economy), Korea, under the Convergence-ITRC (Convergence Information Technology Research Cen-ter), supervised by the NIPA (National IT Industry Pro-motion Agency), (NIPA-2013-H0401-13-1003) and a grant(code# 2010-0019373, 2011-0010300, 2012R1A2A1A01007405,2013R1A1A2057502, and 2014R1A1A3A04051296) from theNational Research Foundation of Korea (NRF) funded by theKorea government.

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