The research on weld pool morphology and passive film characteristic of high-nitrogen stainless laser-arc hybrid weld joint

Abstract

In this paper, the dynamic weld pool morphology and metallographic structure on each zone of high-nitrogen stainless hybrid weld was investigated. By electrochemical test, the corrosion mechanism and evolution characteristic of passive film on weld surface was analyzed. It was found that by the laser keyhole stirring effect, the weld laser zone exhibited better ferrite dendrites distribution and corrosion resistance. By polarization method, it is observed that the weld passive film exhibited different morphology characteristic in each evolution stage. The passive film had strong regional tendency to ferrite dendrites structure in early stage. And the addition of molybdenum optimized the semiconductor properties of outer weld passive layer. For the failure stage, the passive film was greatly affected by Cr depleted zone and combined with the mode of cracking and dissolution.