E16-25MoN焊丝熔敷金属高温失塑裂纹敏感性及微观组织分析

Analysis on High Temperature Ductility-Dip Crack Sensitivity and Microstructure of E16-25MoN Welding Wire Deposited Metal

采用钨极氩弧焊制备了E16-25MoN焊丝熔敷层,采用Gleeble热模拟试验机对熔敷金属试样进行了不同温度、不同应变量的拉伸试验。结果表明:在850~1150℃内,E16-25MoN焊丝熔敷金属的高温失塑裂纹敏感程度较高,1000℃时敏感程度最高,该温度下裂纹临界应变量变低于6%。通过组织分析发现高温失塑裂纹的产生受晶界平直形貌和晶界析出物的影响,高温时晶界上析出物阻碍位错移动,形成应力集中最终产生开裂,而平直晶界为裂纹扩展提供了有利条件。

E16-25MoN welding wire cladding layer was prepared by using argon tungsten arc welding,and the tensile experiments at different temperatures and strains were carried out by using Gleeble thermal simulation machine.The results show that the high temperature ductility-dip crack(DDC)sensitivity of the deposited metal is high in the range of 850-1150℃,and the high temperature DDC sensitivity of the deposited metal is the highest at 1000℃,and the critical strain at cracking at this temperature is lower than 6%.Through the microstructure analysis,it is found that the production of high temperature DDC is affected by the flat morphology of grain boundary and the grain boundary precipitates.At high temperature,the precipitates at the grain boundary hinder the movement of dislocations,resulting in stress concentration and eventually cracking,while the flat grain boundaries provide favorable conditions for crack propagation.