Evolution of Soft Zone in a Simulated 1.25Cr-0.5Mo Steel-Welded Joint During Post-weld Heat Treatment

In the present study, the effect of post-weld heat treatment on the soft zone of 1.25Cr-0.5Mo steel welded joint has been systematically studied. Outstanding features of the soft zone, including grain size, number density of carbides, volume fraction of carbides, and hardness distribution, are quantitatively analyzed by means of scanning electron microscopy and a microhardness testing. Results show that ferrite grain growth, carbide coarsening, and alloying element segregation are main factors accounting for hardness variations.