Microstructure and Crack Propagation Characteristics of SUS301L-HT Laser-MAG Hybrid-Welded Joint

Wu Xiangyang; Zhao Xu; Chen Hui; Zhang Zhiyi

doi:10.3788/CJL202047.0902002

Chinese Journal of Lasers, Volume. 47, Issue 9, 902002(2020)

Microstructure and Crack Propagation Characteristics of SUS301L-HT Laser-MAG Hybrid-Welded Joint

Wu Xiangyang^1,2, Zhao Xu^2,3, Chen Hui^2、*, and Zhang Zhiyi^1,2

Author Affiliations

¹CRRC Qingdao Sifang Locomotive & Rolling Co., Ltd., Qingdao, Shandong 261111, China

²School of Material Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China

³State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu, Sichuan 610031, China

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Figures & Tables(14)

Fig. 1. Shape and geometric dimension for crack propagation sample

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Fig. 2. Schematic map for welding and optimal processing parameters

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Fig. 3. Dimension for cross section of macro welded joint

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Fig. 4. Microstructures and hardness profile for welded joint. (a) Base metal; (b) weld center; (c) coarse grain zone; (d) fine grain zone; (e) incomplete phase transition zone; (f) hardness profile

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Fig. 5. Binarization for microstructure. (a) Original image; (b) processing image

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Fig. 6. Results for crack propagation experiment. (a) Crack length; (b) crack propagation rate curve

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Fig. 7. Characteristics for crack morphology. (a) Global feature; (b) crack initiation zone; (c) crack stable propagation zone 1; (d) crack stable propagation zone 2; (e) crack tip zone

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$Fracture morphology and feature analysis. (a) Macro fracture; (b) micro fracture; (c) stable crack propagation zone; (d) composition analysis$

Fig. 8. Fracture morphology and feature analysis. (a) Macro fracture; (b) micro fracture; (c) stable crack propagation zone; (d) composition analysis

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Fig. 9. Network distribution feature for ferrite

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Fig. 10. Curve for crack propagation behavior

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Table 1. Main chemical composite of SUS301L-HT stainless steel and filler metal
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Table 1. Main chemical composite of SUS301L-HT stainless steel and filler metal
Material Mass fraction /%
C Si Mn P S Cr Ni Cu N
SUS301L-HT 0.02 0.39 1.12 0.034 - 17.24 7.10 0.0460 0.10
ER308L 0.02 0.42 1.65 - - 20.1 10.3 0.0460 0.10

Table 2. Load for crack propagation experiment
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Table 2. Load for crack propagation experiment
Stress ratio Maximumload P_max /kN Minimumload P_min /kN
0.1 4.0 0.4
0.3 5.14 1.54
0.5 7.2 3.6

Table 3. Quality assessment for welding imperfections

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Table 3. Quality assessment for welding imperfections

Class	Quality grade
Class	D grade	C grade	B grade
Reinforcement	h₁≤1 mm+0.25l₁ & h₁≤10 mm	h₁≤1 mm+0.15l₁ & h₁≤7 mm	h₁≤1 mm+0.1l₁ & h₁≤5 mm
Excessive penetration	h₂≤1 mm+1.0l₂ & h₂≤5 mm	h₂≤1 mm+0.6l₂ & h₂≤4 mm	h₂≤1 mm+0.3l₂ & h₂≤3 mm

Table 4. Crack propagation parameters
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Table 4. Crack propagation parameters
Stress ratio Crack propagationexponent m Logarithmic crackpropagationcoefficient lg C
0.1 2.697 -7.432
0.3 2.821 -7.393
0.5 2.692 -6.996

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Wu Xiangyang, Zhao Xu, Chen Hui, Zhang Zhiyi. Microstructure and Crack Propagation Characteristics of SUS301L-HT Laser-MAG Hybrid-Welded Joint[J]. Chinese Journal of Lasers, 2020, 47(9): 902002

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