Correlation of Mechanical and Microstructural properties in SMAW welded Cr-Mo Boiler steels subjected to different Post Weld Heat Treatment soaking times.

In the present work the effect of different durations of post weld heat treatment soaking times (0.5,2,10,50 hours) are analyzed on the mechanical and microstructural properties of Cr-Mo alloy steel of ASTM A387 Gr-22,2.25% Cr-1%Mo alloy steel. These are used in high temperature services in steam generation applications, Oil and Gas industries, Thermal and Nuclear power plants etc. The work was focused on different regions of weldment like base metal, heat affected zone and weld metal to compare and analyze the results obtained in as-welded and different soaking times from hardness test and microstructural examination. Results showed that the hardness varies from weld centre line to base metal and peak hardness was found in the heat affected zone. The hardness is reduced to large extent when post weld heat treatment is done at 50 h. Microstructural changes were observed during different post weld heat treatments and their effect on mechanical properties and best suitable soaking times were reported.