Welding of high strength low alloy steels (HSLA) involve usage of low, even and high strength filler metal than the parent metal depending on the application of the welded structures and the availability of the filler material. In the present investigation, the effect of strength mis-match ratio on tensile and impact behaviour of under matched (UM), equal matched (EM) and over matched (OM) welded joints have been studied. The base metal used in this investigation is HSLA 80 steel of weldable grade. Shielded metal arc welding (SMAW) process has been used to fabricate the single 'V' butt joints. Post weld heat treatment of stress relief annealing at 600°C for 1 hour and cryogenic treatment at -190°C using liquid nitrogen for 1 hour have been carried out. The influences of strength mismatch, post weld heat treatment and cryogenic treatment on tensile and impact behaviour has been analysed in detail.
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