回火冷却速度对贝氏体焊缝韧性的影响  

Effect of the tempering cooling rate on the toughness of bainite welds

作　　者：蔡志鹏[1] 王梁[1] 潘际銮[1] 乔尚飞 霍鑫 王朋 刘霞[1,2] 

机构地区：[1]清华大学机械工程系,北京100084 [2]上海电气电站设备有限公司上海汽轮机厂,上海200240

出　　处：《清华大学学报（自然科学版）》2015年第10期1045-1050,共6页Journal of Tsinghua University(Science and Technology)

基　　金：上海市科学技术委员会科研计划项目(13DZ1101500)

摘　　要：大尺寸厚壁构件在回火过程中冷却速度较慢。对于CrMoV钢,若回火参数不当,容易引起回火脆性。该文针对大尺寸厚壁环形试验件,研究了回火冷却速度对贝氏体焊缝韧性的影响。结果表明:当回火冷却速度过慢时,焊缝金属会发生明显的韧性降低现象;多层多道焊焊缝脆性断口具有特殊的分层现象,说明较慢的回火冷速只是使得焊缝局部韧性下降,其中层间热影响区弱化程度最为明显。通过Auger分析等方法进一步研究发现,韧性减低现象的产生与C、O元素在原奥氏体晶界的偏聚以及Ni元素在原奥氏体晶界处的含量减少有关。Large components with thick walls have slow cooling rates during tempering. Improper tempering parameters can cause temper brittlement in CrMoV steels. The effect of tempering Cooling rate on the toughness of bainite welds is investigated for thick circular components. Slow tempering cooling rates reduce the weld toughness. Multi-layer, multi-pass welds experience layered brittle fracture, which illustrates that slow tempering cooling rates affect only local welds with the greatest toughness reduction in the heat affected zone （HAZ） between the layers. Auger electron spectroscopy （AES） analyses show that the segregation of C, O and Ni along the prior austenite grain boundaries is associated with the toughness reduction.

关 键 词：多层多道焊焊接 韧性降低 元素偏聚 大尺寸厚壁构件 

分 类 号：TG407[金属学及工艺—焊接]