Grain‐boundary behaviour in the heat affected zone of an austenitic stainless steel and its relation to weld metal grain growth

Summary

This paper describes an investigation of the effects of the welding speed and external restraint on grain growth in the heat affected zone of an austenitic stainless steel, as well as its relation to the growth behaviour of weld metal grains growing epitaxially from the bond. The following results are obtained.

The restraint during welding hardens the heat affected zone through the plastic thermal strain arising during heating, resulting in considerable grain coarsening in the heat affected zone after heating above 1400 ∼ 1500 K. Despite the grain size in the heat affected zone being coarsened by the restraint, there is virtually no difference between the columnar width of the weld metal and that obtained under restraint‐free welding. A bond region where there is no epitaxial relationship between the weld metal and heat affected zone often appears when coarsening occurs in the heat affected zone under heavy plastic strain during welding.