针对锻态高锰孪生诱导塑性钢利用Gleeble3500型热模拟试验机，通过设置不同峰值温度(850，950，1 050，1 150，1 250 ℃)对焊接接头热影响区的各个区间进行了焊接热模拟，采用电子背散射衍射系统、扫描电子显微镜和X射线衍射仪等手段分析了锻态母材经过焊接热作用后组织和性能的变化. 结果表明，热作用前后孪生诱导塑性钢组织均为等轴晶粒的全奥氏体组织，晶粒尺寸随峰值温度的上升先减小后增加，但都低于母材；热影响区的拉伸性能均优于母材，主要原因是发生了细晶强化；冲击韧性随峰值温度的变化与晶粒尺寸变化趋势一致，说明晶粒尺寸对采用的孪生诱导塑性钢冲击韧性有关，晶粒尺寸越细，冲击韧性越差. 冲击断口的韧窝底部发现有AlN颗粒.
In this paper, the welding thermal simulation was performed on the forged high-Mn twinning induced plasticity steel by setting different peak temperatures (850, 950, 1050, 1 150 and 1 250 ℃) in each interval of the heat affected zone of the welded joint using the Gleeble 3500 thermal simulation tester. Electron backscatter diffraction system, scanning electron microscopy and X-ray diffraction were used to analyze the changes in the microstructure and properties of the forged base material after the thermal action of welding. The results show that the microstructure of twinning induced plasticity (TWIP) steel before and after the thermal action is all-austenitic with equiaxed grains, and the grain size firstly decreases and then increases with the rise of the peak temperature, but is still lower than that of the base material. The tensile properties in the heat-affected zone are better than those of the base material, mainly due to the occurrence of fine grain strengthening. The impact toughness of the twin-induced plasticity steel is related with grain size in this study, and the finer the grain size, the worse the impact toughness. AlN particles were found at the bottom of the dimple of the impact fracture.
[1] Gwon H, Kim J K, Jian B, et al. Partially-recrystallized, Nb-alloyed TWIP steels with a superior strength-ductility balance[J]. Materials Science & Engineering: A, 2018, 711: 130-139.
[2] 陶嘉, 吴杰峰, 刘志宏, 等. 超导腔束管与法兰接头处Nb/Nb55Ti焊接工艺试验[J]. 焊接学报, 2021, 42(3): 77-84
Tao Jia, Wu Jiefeng, Liu Zhihong, et al. Nb/Nb55Ti welding process test at the joints of tubes and flanges in superconducting cavities[J]. Transactions of the China Welding Institution, 2021, 42(3): 77-84
[3] Wang H H, Meng L, Luo Q, et al. Superior cryogenic toughness of high-Mn austenitic steel by welding thermal cycles: The role of grain boundary evolution[J]. Materials Science & Engineering:A, 2020, 788: 139573.
[4] Liu W, Lu F, Yang R, et al. Gleeble simulation of the HAZ in Inconel 617 welding[J]. Journal of Materials Processing Technology, 2015, 225: 221-228.
[5] Wang J, Shen Y F, Xue W Y, et al. The significant impact of introducing nanosize precipitates and decreased effective grain size on retention of high toughness of simulated heat affected zone (HAZ)[J]. Materials Science & Engineering: A, 2021, 803: 140484.
[6] 刘龙龙. 高性能Fe-Mn-Cu-C TWIP钢板材制备及力学性能的研究[D]. 福州: 福州大学, 2014.
Liu Longlong. Investigation on preparing process and mechanical property of Fe-Mn-Cu-C TWIP steel plate[D]. Fuzhou: Fuzhou University, 2014.
[7] De Cooman B C, Estrin Y, Kim S K. Twinning-induced plasticity (TWIP) steels[J]. Acta Materialia, 2018, 142: 283-362.
[8] Chen J, Dong F, Jiang H, et al. Influence of final rolling temperature on microstructure and mechanical properties in a hot-rolled TWIP steel for cryogenic application[J]. Materials Science & Engineering: A, 2018, 724: 330-334.
[9] Yang J, Dong H, Xia Y, et al. Carbide precipitates and mechanical properties of medium Mn steel joint with metal inert gas welding[J]. Journal of Materials Science & Technology, 2021, 75: 48-58.
[10] García-García V, Mejía I, Reyes-Calderón F. Experimental and FEM study of Ti-containing TWIP steel weldability[J]. Journal of Materials Processing Technology, 2018, 261: 107-122.
[11] Kumar S, Shahi A S. Studies on metallurgical and impact toughness behavior of variably sensitized weld metal and heat affected zone of AISI 304L welds[J]. Materials & Design, 2016, 89: 399-412.
