Cooling rate predictions and its correlation with grain characteristics during electron beam welding of stainless steel

Abstract

Cooling rate of the weld during solidification has significant influence on metallurgical and mechanical properties of welded joint. In the present study, cooling rates have been predicted during electron beam welding of AISI 304 stainless steel for different values of energy input per unit length using physics-based phenomenological model and commercial finite element analysis. Cooling rates predicted by the above models have been validated with the experimental cooling rate estimated indirectly from the secondary dendritic arm spacing (SDAS) obtained in the microstructure of the welded sample. The predicted cooling rate is observed to vary inversely with the energy input per unit length, as expected. It has also been correlated with the grain characteristics like grain size and grain boundary character distribution (GBCD) obtained by EBSD analysis of the weld metal. An increase in low-angle boundary has been observed with the increase in cooling rate, which has been attributed to an increase in dislocation density.