Structure–property relationships in heat-affected zone of gas-shielded arc-welded V–N microalloyed steel
Jun Hu1 . Lin-xiu Du1 . Bin Zhang1 . Xiang-yu Qi1 . Xiu-hua Gao1 . R.D.K. Misra2
1 The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, Liaoning, China 2 Laboratory for Excellence in Advanced Steel Research, Department of Metallurgical, Materials and Biomedical Engineering, University of Texas at El Paso, El Paso, TX 79968-0521, USA
Structure–property relationships in heat-affected zone of gas-shielded arc-welded V–N microalloyed steel
Jun Hu1 . Lin-xiu Du1 . Bin Zhang1 . Xiang-yu Qi1 . Xiu-hua Gao1 . R.D.K. Misra2
1 The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, Liaoning, China 2 Laboratory for Excellence in Advanced Steel Research, Department of Metallurgical, Materials and Biomedical Engineering, University of Texas at El Paso, El Paso, TX 79968-0521, USA
摘要 The structure–property relationship in heat-affected zone (HAZ) of a low-carbon steel bearing V–N subjected to gasshielded arc welding was explored. The microstructural characteristics of base metal (BM), coarse-grained HAZ (CGHAZ), fine-grained HAZ, and intercritical HAZ were significantly different. The effect of grain-refinement strengthening and transformation hardening on HAZ contributed to equivalent hardness of 260.8–278.5 HV in comparison with BM hardness of 272.0 HV. Moreover, excellent impact toughness at - 20 °C was obtained because of high resistance to crack propagation by high-misorientation boundaries, leading to impact fracture consisting of dimples. In CGHAZ, free N was partly fixed by V(C, N) precipitates, such that the deterioration effect of N on toughness was considered to be nearly eliminated. In comparison with CGHAZ, weld metal contained higher fraction of acicular ferrite with fine plates, while the impact toughness was inferior because of the detrimental influence of coarse inclusions from the welding wire. The nanoscale V(C, N) precipitates in CGHAZ had weak effect on toughness because of small size.
Abstract:The structure–property relationship in heat-affected zone (HAZ) of a low-carbon steel bearing V–N subjected to gasshielded arc welding was explored. The microstructural characteristics of base metal (BM), coarse-grained HAZ (CGHAZ), fine-grained HAZ, and intercritical HAZ were significantly different. The effect of grain-refinement strengthening and transformation hardening on HAZ contributed to equivalent hardness of 260.8–278.5 HV in comparison with BM hardness of 272.0 HV. Moreover, excellent impact toughness at - 20 °C was obtained because of high resistance to crack propagation by high-misorientation boundaries, leading to impact fracture consisting of dimples. In CGHAZ, free N was partly fixed by V(C, N) precipitates, such that the deterioration effect of N on toughness was considered to be nearly eliminated. In comparison with CGHAZ, weld metal contained higher fraction of acicular ferrite with fine plates, while the impact toughness was inferior because of the detrimental influence of coarse inclusions from the welding wire. The nanoscale V(C, N) precipitates in CGHAZ had weak effect on toughness because of small size.
HU Jun,DU Lin-Xiu,ZHANG Ban, et al. Structure–property relationships in heat-affected zone of gas-shielded arc-welded V–N microalloyed steel[J]. Journal of Iron and Steel Research International, 2018, 25(12): 1244-1254.
[1]
R.D.K. Misra, H. Nathani, J.E. Hartmann and F. Siciliano: Mater. Sci. Eng. A, 394 (2005), 339-352.
[2]
C.L. Davis and J.E. King: Metall. Mater. Trans. A, 25 (1994), 563-573.
[3]
X.H. Yu, J.L. Caron, S.S. Babu, J.C. Lippold, D. Isheim and D.N. Seidman: Acta Mater., 58 (2010), 5596-5609.
[4]
R. Lagneborg, T. Siwecki, S. Zajac and B. Hutchinson: Scand. J. Metall., 28 (1999), 186-241.
[5]
T. Senuma: ISIJ Int., 42 (2002), 1-12.
[6]
J. Hu, L.X. Du, J.J. Wang, H. Xie, C.R. Gao and R.D.K. Misra: Mater. Sci. Eng. A, 585 (2013), 197-204.
[7]
J. Hu, L.X. Du, H. Xie, X.H. Gao and R.D.K. Misra: Mater. Sci. Eng. A, 607 (2014), 122-131.