Outline - 大阪大学 · ... forum and seminar ... report in the commission on welding metallurgy,...

The state-of-the-art and future prospects of research on weldingmetallurgy in Japan

Kenji SHINOZAKIHiroshima University, Higashi-Hiroshima, Japan

[email protected], +81-82-424-7570

AbstractThe road map for future research over 10 years concerning welding and joining was discussed in

each eight technical commissions in JWS in 2010 under the following philosophy. (I) To construct asustainable, stable and growth society (to construct a safe and secure society). (II) To innovatewelding and joining technology. (III) To pull out of welding and joining technology called “specialprocess”/ remedies for shortages of welding engineers and researchers.

The technical issues and target concerning the welding metallurgy in future based on the abovephilosophy was discussed and the road map for future research over 10 years was made in thetechnical commission on Welding Metallurgy.

The road map for welding metallurgy research and recent researches concerning welding metallurgysuch as development of welding consumables, modeling/simulation and visualization, dissimilarwelding and joining, and joining technologies for advanced materials are introduced.

Hiroshima University Graduate School of Engineering

Outline

1. Activities of the Commission on WeldingMetallurgy in JWS

2. Road map for research on welding metallurgyin Japan

2.1 Technical issues and target in future

2.2 Trends on welding metallurgy in Japan

3. Introduction of recent researches on weldingmetallurgy in Japan


The Commission on Welding Metallurgy in JWS

Welding Metallurgy

Welding Process

Welding Mechanics and Design

Interfacial Joining

Micro Joining

Joining and Materials Processing for Light Structures

High Energy Beam Processing

Fatigue Strength

Eight technical commissions in JWS


History and activities of the commission on welding metallurgy

【The establishment year】 1960【The first chairman】 Prof. I. OHNISHI （Osaka University）【Present chairman】 Prof. K. SAIDA (Osaka University)【An action policy】

“The commission aims to study the most advancedresearch in welding metallurgy and to become anauthoritative and worldwide”【Number of members】 68

University professors: 37Researchers in companies: 31

【Activities】① Regular meeting fourth a year② Organizing symposium, forum and seminar③ Publication


Recent main publications

No.Publish

year Title Pages

1 2016 Simulation and visualization of phenomena regarding welding metallurgy 495

2 2013 Metallographic atlas of steel and non-ferrous alloy welds (a new edition) 721

3 2003 Progress and future prospect of research in welding metallurgy 411

4 1999 Modeling and simulation on metallographic behavior of weld zone 342

5 1984 Metallographic atlas of steel and non-ferrous alloy welds 490

6 1982 Fractographic atlas of steel welds 550

2 21


Road map for research on welding metallurgy in Japan

Road map for research in welding & joining wasdiscussed in JWS in 2010 under the following philosophy.

(Ⅰ) To construct a sustainable, stable and growth society (toconstruct a safe and secure society)

(i) through to produce sound and high performance weld joint(Ⅱ) To Innovate welding and joining technology

(ii) through to weld the next generation materials and to developnew welding & joining process

(Ⅲ) To pull out of welding & joining technology called “specialprocess”/ remedies for shortages of welding engineers andresearchers(iii) through to sophisticate and systematize material science of

welding


Technical issues-(i) to produce soundness and high performance weld joint -

(i-1) Realization of weld cracking and defect-freejoint

(i-2) Improvement of welded joint properties (highstrength, high toughness and high corrosionresistance)

(i-3) Improvement of the reliability of the weldrepair and maintenance technology


Technical issues- (ii) to weld the next generation materials and to develop

new welding & joining process -

(ii-1) Development of welding and joiningtechnology for the next generation material

(ii-2) Elucidation of the metallurgical phenomenonin new welding and joining process

(ii-3) Sophistication of dissimilar welding andjoining technology


Technical issues-(iii) to sophisticate and systematize material science of welding-

(iii-1) Visualization and modeling of metallurgicalphenomenon of weld zone


Example of road map(i-1) Realization of weld cracking & defect-free joint

Technical issues

Technical target

(i-1) Realization

of weld cracking &defect-free

joint

Estab-lishment ofweldingtechnology

・Steels・ Corrosion-resistantsteels・Light alloys

To make clear the crackand defect condition

To elucidate the cracking mechanism

To elucidate the dominantfactor and to evaluate itquantitatively

To design the materialwithout crack and defect

2010 2015 2020


Number of reports published from 2000 to 2016 in theCommission on Welding Metallurgy regardingtechnical issues in road map

(i-1) Realization of weld cracking &defect-free joint

(i-2) Improvement of welded jointproperties

(i-3) Improvement of the reliability of theweld repair and maintenance technology

(ii-1) Development of welding and joiningtechnology for the next generation material

(ii-2) Elucidation of the metallurgical phenomenonin new welding and joining process

(ii-3) Sophistication of dissimilar weldingand joining technology

(iii-1) Visualization and modeling ofmetallurgical phenomenon of weld zone

Technical issues

Hiroshima Univ.Graduate School of Engineering

Introduction of recent researches onwelding metallurgy in Japan


Example of recent researches on weldingmetallurgy in each technical issues

(i-1) Realization of weldcracking & defect-free joint

Development of filler wire for HT980 steel welds without preheating Hot cracking susceptibility of ultra high purity stainless steels

(i-2) Improvement ofwelded joint properties

Mechanical properties of ultra-fine grained high strength steels welded by high powerlaser

(ii-2) Elucidation of themetallurgical phenomenonin new welding and joiningprocess

Clarification of defect formation mechanism in friction stir welding by X-rayradiography

(ii-3) Sophistication ofdissimilar welding andjoining technology

Evaluation of solidification cracking susceptibility of stainless steel on Schaefllerdiagram

(iii-1) Visualization andmodeling of metallurgicalphenomenon of weld zone

Analysis of solidification process on austenitic stainless steel weld metal usingsynchrotron radiation

In-situ observation of solidification front during laser welding Prediction of hardness in HAZ of multi-pass welds in low-alloy steel using neural

network Prediction of occurrence of solidification cracking during laser welding by in-situ

observation

In-situ observation method → to understand phenomena preciselyModeling and simulation → to predict phenomena Dissimilar welding and joining → to take advantage of multi-materials


Development of filler wire for HT980 steel welds without preheating

C Si Mn Ni Cr Mo N Fe

NR1 0.027 0.27 0.80 7.10 13.45 0.47 0.0055 Bal.

NR2 0.028 0.27 0.80 8.16 13.37 0.46 0.0055 Bal.

NR3 0.028 0.31 0.79 8.45 13.40 0.51 0.0056 Bal.

NR4 0.028 0.27 0.80 9.07 13.43 0.47 0.0057 Bal.

NR5 0.029 0.32 0.80 9.83 13.05 0.51 0.0055 Bal.

RA6 0.014 0.36 0.80 7.89 13.52 0.52 0.0060 Bal.

RA7 0.071 0.32 0.81 8.87 13.50 0.51 0.0055 Bal.

RA8 0.049 0.33 0.81 8.85 13.47 0.53 0.0053 Bal.

RA9 0.014 0.32 0.81 6.93 13.50 0.53 0.0055 Bal.

13%Cr + 7-9%Ni steels

■ NR-series varied in Ni content, and RA-series additionally varied in C content.

The new filler metals for HT980high strength steel consist of Fe-Cr-Ni ternary alloys weredeveloped in order to weldwithout preheating utilizingretained in national projectprogram.

K. Saida et al.: Science and Technology of Welding and Joining, 15, 3(2010), 185-193


Weld metal

Base metal

HAZ

Micro-model analysis

H concentration (ppm)M

M

M

MM

MM

γγ

Austenite trapped a large amountof H in a cell.

H was accumulated in M at cell boundaries.

Maximizing H concentrationin M of M/γ interface

Micro-distribution of hydrogen in microstructure

K. Saida et al.: report in the commission on welding metallurgy, WM-2067-08, (2008)


RA9 RA6 NR1 NR2 NR3 RA8 NR4 RA7 NR5

Amount of retained (%)

1.46 1.64 3.41 9.59 14.9 22.6 34.8 36.7 58.8

Tensile strength

>880MPa○ ○ ◎ ○ ○ ○ ○ △ ×

Toughness

>88J/cm2 × × × × △ ○ ○ ○ ◎

Hot cracking>SUS304 △ ○ ○ ◎ ○ × ○ × ×

Cold cracking Crack-free ○ ○ × × ○ ○ ○ ○ ○

Summary of welding performances of triplexstainless steels

Excellent◎ ○ △ × PoorFairGood

NR3 & NR4 clear the all requirements.NR4 is superior to NR3 (low temp. toughness)

New welding consumable for HT980 could be designed by controlling the amount of retained austenite (approx. 15-35%).

K. Saida et al.: Science and Technology of Welding and Joining, 15, 3(2010), 185-193

Hiroshima University Graduate School of EngineeringChemical compositions of lab-melting EHP steels

(varying P, S, C and Mn contents)Chemical compositions of lab-melting EHP steels

(varying P, S, C and Mn contents)

Transverse-Varestraint testTransverse-Varestraint test

RBending block

Yoke

Specimen

TIG torch

Yoke Arc current : 150AArc voltage : 14VWelding speed : 1.67mm/s

Augmented strain : 0.15-0.83%

Essential effect of impurity & minor elements onsolidification cracking susceptibility

K. Saida et al.: Quarterly J. of JWS, 31,1 (2013), 56-65


Essential contribution to enlarging BTRP：S：C＝1：1.3：0.56

Mn : Negligibly improves S.C. susceptibility (reducing BTR)

Effect of C, P, S, Mn contents on BTR Potency atomic factor for enlarging BTR

← Advantage from previous results of conventional steels

Contribution of impurity & minor elements to BTRevaluated by Trans-Varestraint test

K. Saida et al.: Quarterly J. of JWS, 31,1 (2013), 56-65


Mechanical properties of ultra-fine grained high strength steels welded by high power laser

Fig. 2 SEM m icrostructures of ul tra-fine grained highstrength steel bar.

Fig. 6 D istributions of hardness and ferrite grain size in H AZof 0.05% C ultra-fine grained high strength steel

（ welding speed : 0.033 m/s）.Fig. 7 Relationship between notch location (HAZ, Bond and Weld

metal) and critical CTOD value.

Steel A

Steel A Steel B

Tensile test of weld joint ofSteel C by LBW: 706MPa(broken at the base metal)

T. Otani et al.: Quarterly J. of JWS, 21,2 (2003), 267/ 21,3(2003), 425


In-situ observation of metal flow in friction stirwelding using X-ray radiography

Y. Morisada and H. Fujii et al.: Quarterly J. of JWS, 32,1 (2014), 31-37

Metal flow during friction stir welding was observed throughbehavior of tracer observing by two direction X-ray radiography.


ASRS

Adequate condition: 600 rpm

Defect formation: 400 rpm

⽋陥

ASRS

AS

RS

AS

RS

Clarification of defect formationmechanism in friction stir welding

Cross section of friction stir welds

Concentriccircle flowpatternaroundprobe

A stagnantflow islocated.rotating

direction =movingdirection oftool

Y. Morisada and H. Fujii et al.: Quarterly J. of JWS, 32,1 (2014), 31-37


Evaluation of solidification cracking susceptibilityin austenitic region on Schaefller diagram

Solidification cracking susceptibility of austenitic region on Schaefller diagram wasquantitatively evaluated by Trans-Varestraint test using laser welding.


Analysis of solidification process on maritensiticstainless steel weld metal using synchrotron radiation

H.Terasaki et al.: Materials letters, 74(2012), 187-190

Schematic illustration of time-resolved in-situobservation under rapid cooling for TIG welding

Wide-area detector

Diffraction beam

Water-cooled copper plate

Power: 10V, 150A

Torch scan (〜1mm/s)

Incident beam

Sample

Base metal: Martensitic stainless steel0.026C-0.34Si-0.82Mn-14Cr-8.2Ni-Fe (mass %)

Photon energy: 30 keVTime resolution: 0.1 s


Multi-dimensional (Time (Temp)-2q (Q)-Count)analysis of solidification weld

Dynamic diffraction from weld pool(halo pattern)

Dynamic diffractionduring solidificationprocess

Non-thermodynamic equilibrium of weld solidification

H.Terasaki et al.: Materials letters, 74(2012), 187-190


Residual liquid metal observed during laser welding

The area among fusion boundaryand white dot line show the areawhere residual liquid observed.Various materials clearly showdifferent size of residual liquid metalexisting zone. The region of IS36and SUS347 are much wider thanthose of other materials.

IS16(Inco.600/347=16/84) IS36(Inco.600/347=36/44) IS55(Inco.600/347=55/45)

K. Shinozaki et al.: Materials Science Forum, 782,3(2014), 3-7


Residual liquid metal and TL-TS*

Blue mark shows TL-TS*, which isobtained from high temperatureductility curves. This value mayindicate approximate BTR.Red mark shows the temperaturerange of the apparent residual liquidmetal according to in-situobservation.Comparing with both lines,although the absolute value aredifferent, the dependence of Inconel600 fraction in weld metal to thetemperature range is quite similar.This result means that the in-situobserved residual liquid metal cantell the tendency of solidificationtemperature range of variousmaterials, which may be used toevaluate solidification crackingsusceptibility.



Measurement of ductility curve at high temperature using in-situ observation

1.9mm

4.5mm

In-situ observation ofsolidification crack usingU-type hot cracking test

Strain-Temperature curve Ductility curve betweenliquidus (TL) and solidus(Ts) temperature



Prediction of solidification cracking

SUS347

Strain curves during welding in U-type hotcracking test were calculated by FEM.

U-type hot cracking test results

P. Wen, K. Shinozaki et al.: Quarterly J. of JWS,27,2(2009), 139s-143s


Calculated by Neural Network

400℃≤Tp≤1500℃Tp<400℃(All cycles)

Tp>1500℃(One cycle)

BM WMHAZ

1-cycleTp, CR

(2 Parameters)

1-cycle + temperTp1,CR1,TCTP

(3 Parameters)

2-cycleTp1,CR1,Tp2,CR2

(4 Parameters)

Hardness distribution in HAZ of temper bead welding

Thermal cycles Calculation with FEM

A533B: Tm =1500 ℃

2-cycle + temperTp1,CR1,Tp2,CR2,TCTP

(5 Parameters)

Y.Lina, K. Saida et al.: Quarterly J. ofJWS, 29,3(2011), 154-161

Prediction of hardness in HAZ of multi-pass welds in low-alloy steel using neural network


The predicted hardness in all region was lower than 350HV(the required specification in practical application)

The predicted hardness in all region was lower than 350HV(the required specification in practical application)

(mm)

BM

Predicted hardness distribution calculated by FEM results (7 Layer–88 pass)

Y.Lina, K. Saida et al.: Quarterly J. of JWS, 29,3(2011), 154-161


・The calculated hardness was in good accordance with measured ones. ・Max. hardness in HAZ was reduced to 350HV during temper bead welding.

Comparison between calculated values andmeasured ones (Hardness)

Y.Lina, K. Saida et al.: Quarterly J. of JWS, 29,3(2011), 154-161


Thank you for yourkind attention!!

Hiroshima UniversityItsukushima shrine at Miyajima

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