On the Hot Cracking in Weld Metal

Abstract

The effects of carbon, manganese, phosphor, sulphur and nickel on the hot cracking and micro segregation of weld metal were examined in submerged arc welding process using the electron probe microanalyser.
Based on the results of this study, the following conclusions are drawn:
1) Segregation of sulphur concentration is larger in weld metal containing more than 0.1% C than one containing less than 0.1% C, and manganese behaves in the same manner as sulphur.
2) Micro segregation or hot cracking of weld metal containing nickel is strongly influenced by the phase solidified as primary crystal in Fe-Ni diagram. Moreover newly solidified
phase by peritectic reaction: δ+Liquid→γ
promotes segregation of sulphur and phosphor concentration.
3) Prime cause of hot cracking in weld metal is sulphur segregation, and the effect of phosphor can be considered as far less than that of sulphur.