Grain refinement and hardness distribution in cryogenically cooled ferritic stainless steel welds

The energy input and heat dissipation dynamics during fusion welding generates coarse grain in the welds resulting in poor mechanical properties. While grain refinement in welds via the control of the energy input is quite common, the influence of heat dissipation on grain morphology and properties is not fully established. This paper characterized cryogenically cooled ferritic stainless steel (FSS) welds in terms of grain structure and hardness distribution along transverse and thickness directions. Cryogenic cooling reduces the weld dimension by more than 30% and provides grain refinement of almost 45% compared to conventional weld. The hardness distribution in the thickness direction gives slightly higher profile because of decreased grain growth caused by faster cooling effects of cryogenic liquid.

► Grain refinement was undertaken in AISI 430 FSS welds using cryogenic cooling.
► Flow rates of the cryogenic liquid influenced weld grain structure.
► Cryogenic cooling of welds generates about 45% grain refinement in welds.
► Phase structure of welds is not affected by flow rates of cryogenic liquid.
► Hardness profile in cryogenically cooled and conventional welds is similar.