热输入对Q500CF钢板焊接热影响区组织和冲击性能的影响  

Effect of heat input on microstructure and property of heat affected zone of crack-free steel Q500CF weld joint

作　　者：郭慧英 张宇 何玉春 许红梅 

机构地区：[1]江苏省(沙钢)钢铁研究院,张家港215625

出　　处：《焊接学报》2013年第5期108-112,118,共5页Transactions of The China Welding Institution

摘　　要：通过埋弧焊试验和Gleeble热模拟试验研究了热输入对Q500CF钢热影响区(HAZ)组织和冲击性能的影响.埋弧焊结果表明,热输入为15～50 kJ/cm时,HAZ的-20℃冲击吸收功大于等于146 J;HAZ中熔合线(FL)处冲击吸收功最低且随热输入增大而减小.组织观察表明,随热输入增加,粗晶区组织由15 kJ/cm时的板条贝氏体(LB)和粒状贝氏体(GB)转变为50 kJ/cm时的GB组织;临界粗晶区在晶界上出现了大量1～7μm的M-A组元,导致低温冲击韧性恶化.Gleeble热模拟结果表明,热输入为50～70 kJ/cm时,粗晶区GB组织粗化并导致该区冲击韧性恶化.因此为确保多道焊焊接接头HAZ低温冲击韧性,焊接热输入应限制在15～50 kJ/cm之间.The effect of heat input on microstructure and impact property of heat affected zone(HAZ) of crack-free steel plate Q500CF was examined by using submerged arc welding(SAW) test and Gleeble simulation.It is found that,SAW joint show excellent impact property in HAZ(AKV,-20 ℃ ≥146 J) with heat input between 15 and 50 kJ / cm.Among HAZ,fusion boundary(FL) have the lowest impact value,which decreases with heat input increases.Coarse grained HAZ microstructure of SAW joint changed from a mixture of lath bainite(LB) and granular bainite(GB) at heat input of 15 kJ / cm to a single GB structure at heat input of 50 kJ / cm.A large amount of 1 ～ 7 μm M-A constituents are formed at prior austenite grain boundary at inter-critical coarse grained HAZ,resulting in impact toughness deterioration of this region.Gleeble simulation results show that higher heat input of 50 ～ 70 kJ / cm causes coarsening of GB,which decreases impact toughness of coarse grained HAZ.In conclusion,heat input should be restricted to 15 ～ 50 kJ / cm for sake of impact property of HAZ.

关 键 词：低焊接裂纹敏感性钢 埋弧焊 粗晶热影响区 热模拟 冲击性能 

分 类 号：TG457.11[金属学及工艺—焊接]