焊后热处理对Q690高强钢焊缝金属冲击韧性的影响  

Effect of Post-welding Heat Treatment on Impact Toughness of Q690 High Strength Steel Welded Metal

作　　者：焦继军 曹睿 李义民 王丛元 何伟平 闫英杰 JIAO Jijun;CAO Rui;LI Yimin;WANG Congyuan;HE Weiping;YAN Yingjie(The State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals,School of Materials Science and Engineering,Lanzhou University of Technology,Lanzhou 730050,China;Lanzhou LS Heavy Equipment,Lanzhou 730030,China)

机构地区：[1]兰州理工大学材料科学与工程学院,省部共建有色金属先进加工与再利用国家重点实验室,兰州730050 [2]兰州兰石重型装备股份有限公司,兰州730030

出　　处：《材料导报》2025年第4期127-134,共8页Materials Reports

基　　金：甘肃省重点研发计划项目(23YFGA0057,2022YFB4003000);国家自然科学基金(52175325)。

摘　　要：利用夏比冲击试验、OM、SEM和EBSD等方法研究了焊后热处理对Q690高强钢焊缝金属冲击韧性的影响。结果表明,热处理后,冲击韧性恶化,但随着热处理温度的升高,冲击韧性有所改善。通过起裂源附近的组织发现,不同状态下起裂源附近都存在粗大的块状铁素体,而焊缝中间两相区由于金属处于过热状态,块状铁素体最为粗大,结合冲击功与中间两相区块状铁素体晶粒尺寸的关系,判断中间两相区的块状铁素体为薄弱区域,引起开裂。而关于热处理对冲击韧性的影响,究其原因是热处理过程中,焊缝金属发生回复,细小的板条合并成引起开裂的粗大块状铁素体,使得阻碍能力较强的大角度晶界减少,再加上碳化物在晶界析出,发生晶界脆化,使得冲击断裂模式由焊态的韧性断裂恶化为热处理态的混合断裂。但随着热处理温度的升高,粗大的块状铁素体开始被分割成尺寸较小的相,使得冲击功升高。The effect of post-welding heat treatment on the weld metal impact toughness of Q690 high strength steel was investigated by Charpy impact test,OM,SEM and EBSD.The results show that the impact toughness deteriorates after heat treatment,but the impact toughness improves with the increase of heat treatment temperature.According to the microstructure near the cracking origin,it is found that coarse massive ferrite is appeared near the cracking origin in all specimens,and the massive ferrite in the two-phase zone in the middle of the weld metal is the largest because the weld metal is in an overheated state.Combined with the relationship between the impact work and the grain size of the massive ferrite in the middle two-phase zone,the massive ferrite in the middle two-phase zone becomes a weakest area,which causes final cracking.The reason for the influence of heat treatment on the impact toughness is that during the heat treatment process,the weld metal has a recovery effect,and the fine packets are combined into the coarse massive ferrite that causes cracking,which decreases the fraction of the large angle grain boundaries with strong hindering ability.Coupled with the precipitation of carbide at the grain boundaries,the grain boundary embrittlement occurs,which makes the impact toughness fracture mode deteriorate from ductile fracture of the as-welded state to mixed fracture of the heattreated state.However,with the increase of heat treatment temperature,the coarse massive ferrite began to be divided into smaller phases,which leads to the increase of the impact energy.

关 键 词：Q690高强钢 焊缝金属 冲击韧性 块状铁素体 

分 类 号：TG441[金属学及工艺—焊接]