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 pr...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.展开更多
The effects of filler metal （FM） composition on inclusions and inclusion defects for ER NiCrFe-7 weldments have been investigated and analyzed. Results show that as Al, Ti content in FM increases from 0.14 wt% Al, 0...The effects of filler metal （FM） composition on inclusions and inclusion defects for ER NiCrFe-7 weldments have been investigated and analyzed. Results show that as Al, Ti content in FM increases from 0.14 wt% Al, 0.30 wt% Ti to 0.42 wt% Al, 0.92 wt% Ti, the Al, Ti reduction will increase during welding. Inclusion defects （point-like defects named by welding workers） are prone to form in the high Al, Ti content weldments. Inclusion defects with Mg, Ca, Al, and Ti as major metallic elements have been found on the surface and interior of the weldments, as Al, Ti content in FM is over 0.29 wt% Al, 0.62 wt% Ti. Less -ri content in FM cannot prevent ductility-dip-cracking （DDC） through producing enough intragranular precipitates and lessening intergranular M23C6 precipitates. Nb can be used to replace Ti to reduce the sensitivity of the DDC in the NiCrFe-7 alloy weldments.展开更多
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)
文摘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.
基金support from the key research program of the Chinese Academy of Sciences(Grant No.KGZD-EW-XXX-2)
文摘The effects of filler metal （FM） composition on inclusions and inclusion defects for ER NiCrFe-7 weldments have been investigated and analyzed. Results show that as Al, Ti content in FM increases from 0.14 wt% Al, 0.30 wt% Ti to 0.42 wt% Al, 0.92 wt% Ti, the Al, Ti reduction will increase during welding. Inclusion defects （point-like defects named by welding workers） are prone to form in the high Al, Ti content weldments. Inclusion defects with Mg, Ca, Al, and Ti as major metallic elements have been found on the surface and interior of the weldments, as Al, Ti content in FM is over 0.29 wt% Al, 0.62 wt% Ti. Less -ri content in FM cannot prevent ductility-dip-cracking （DDC） through producing enough intragranular precipitates and lessening intergranular M23C6 precipitates. Nb can be used to replace Ti to reduce the sensitivity of the DDC in the NiCrFe-7 alloy weldments.
