Q690ZM中锰钢的焊接冷裂纹敏感性  

Welding Cold Crack Sensitivity of Q690ZM Medium-Mn Steel

作　　者：齐祥羽 严玲 张鹏 王晓航 杜林秀[3] QI Xiangyu;YAN Ling;ZHANG Peng;WANG Xiaohang;DU Linxiu(State Key Laboratory of Metal Material for Marine Equipment and Application,Anshan 114009,China;Iron and Steel Research Institute of Angang Group,Anshan 114009,China;State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,China)

机构地区：[1]海洋装备用金属材料及其应用国家重点实验室,鞍山114009 [2]鞍钢集团钢铁研究院,鞍山114009 [3]东北大学轧制技术及连轧自动化国家重点实验室,沈阳110819

出　　处：《机械工程材料》2021年第12期7-12,18,共7页Materials For Mechanical Engineering

基　　金：国家高技术研究发展计划重大项目(2015AA03A501)。

摘　　要：采用Ar-CO_(2)气体保护焊通过最高硬度试验和斜Y型坡口焊接冷裂纹试验,研究了Q690ZM中锰钢的焊接冷裂纹敏感性。结果表明:当焊接热输入由10 kJ·cm^(-1)增加至20 kJ·cm^(-1)或预热温度由20℃升高至200℃时,中锰钢焊接热影响区的显微硬度均略微降低,最高硬度均高于430 HV,焊接冷裂倾向严重;当焊接热输入为15 kJ·cm^(-1),预热温度由100℃升高至200℃时,斜Y型坡口焊接裂纹试验中试验焊缝的表面裂纹和根部裂纹逐渐消失,断面裂纹率降低至9.09%。为防止冷裂纹的产生,中锰钢焊前必须进行150~200℃的预热,并进行相应的焊后热处理;粗晶热影响区中粗大的马氏体板条晶体学取向差小,大角度晶界密度低,抵抗解理裂纹扩展的能力弱,因此焊接冷裂纹萌生后沿紧邻熔合线的粗晶热影响区扩展。The sensitivity of welding cold crack of medium-Mn steel was investigated by a maximum hardness test and Y-groove welding cracking test through Ar-CO_(2) gas shielded welding.The results show that when the welding heat input increased from 10 kJ·cm^(-1) to 20 kJ·cm^(-1) or the preheating temperature increased from 20℃to 200℃,the microhardness of the welding heat affected zone of medium-Mn steel decreased slightly,and the maximum hardness was higher than 430 HV,indicating the steel had a severe welding cold cracking tendency.The surface crack and root crack of test weld in Y-groove welding cracking test disappeared and the section crack rate decreased to 9.09%,when the welding heat input was 15 kJ·cm^(-1) and the preheating temperature increased from 100℃to 200℃.In order to prevent welding cold crack formation,the preheating at 150-200℃before welding medium-Mn steel and post-weld heat treatment should be carried out.The large martensitic lath in coarse-grained heat affected zone had little difference in crystallographic orientation and had a low density of large angle grain boundaries,which had weak resistance to cleavage crack propagation;thus,the welding cold crack extended along the coarse-grained heat affected zone adjacent the fusion line after initiation.

关 键 词：中锰钢 焊接冷裂纹敏感性 最高硬度法 斜Y型坡口焊接裂纹法 粗晶热影响区 

分 类 号：TG406[金属学及工艺—焊接]