Effects of Boron on the Microstructure,Ductility-dip-cracking,and Tensile Properties for NiCrFe-7 Weld Metal  

作　　者：Wenlin Mo Xiaobing Hu Shanping Lu Dianzhong Li Yiyi Li 

机构地区：[1]Shenyang National Laboratory for Materials Science,Institute of Metal Research,Chinese Academy of Sciences [2]Key Laboratory of Nuclear Materials and Safety Assessment,Institute of Metal Research,Chinese Academy of Sciences

出　　处：《Journal of Materials Science & Technology》2015年第12期1258-1267,共10页材料科学技术（英文版）

基　　金：financial support by the National Natural Science Foundation of China (No.51474203);Key Research Program of the Chinese Academy of Sciences (No.KGZD-EW-XXX-2)

摘　　要：The distribution of boron and the microstructure of grain boundary（GB） precipitates（M23（C,B） 6 and M 2B）have been analyzed with their effects on the susceptibility of ductility-dip-cracking（DDC） and tensile properties for NiCrFe-7 weld metal,using optical microscopy（OM）,secondary ion mass spectroscopy（SIMS）,scanning electron microscopy（SEM）,and transmission electron microscopy（TEM）.The results show that boron segregates at GBs in NiCrFe-7 weld metal during the welding process.The segregation of boron at GBs promotes the formation of continuous M23（C,B） 6 carbide chains and M 2B borides along GBs.The addition of boron aggravates GB embrittlement and causes more DDC in the weld metal,by its segregation at GBs presenting as an impurity,and promoting the formation of larger and continuous M 23（C,B） 6 carbides,and M 2B borides along GBs.DDC in the weld metal deteriorates the ductility and tensile strength of the weld metal simultaneously.The distribution of boron and the microstructure of grain boundary（GB） precipitates（M23（C,B） 6 and M 2B）have been analyzed with their effects on the susceptibility of ductility-dip-cracking（DDC） and tensile properties for NiCrFe-7 weld metal,using optical microscopy（OM）,secondary ion mass spectroscopy（SIMS）,scanning electron microscopy（SEM）,and transmission electron microscopy（TEM）.The results show that boron segregates at GBs in NiCrFe-7 weld metal during the welding process.The segregation of boron at GBs promotes the formation of continuous M23（C,B） 6 carbide chains and M 2B borides along GBs.The addition of boron aggravates GB embrittlement and causes more DDC in the weld metal,by its segregation at GBs presenting as an impurity,and promoting the formation of larger and continuous M 23（C,B） 6 carbides,and M 2B borides along GBs.DDC in the weld metal deteriorates the ductility and tensile strength of the weld metal simultaneously.

关 键 词：BORON M23C6 M2B Ductility-dip-cracking Tensile properties 

分 类 号：TG407[金属学及工艺—焊接]