Influences of post weld heat treatment on fatigue life prediction of strength mis-matched HSLA steel welds

Welding of High Strength Low Alloy Steels (HSLA) involve usage of low, even and high strength filler materials (electrodes) than the parent material depending on the application of the welded structures and the availability of the filler materials. In the present investigation, the influences of post weld heat treatment (PWHT) on fatigue life prediction of under matched (UM), even matched (EM) and over matched (OM) weld metals have been studied. The base material 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. Centre Cracked Tension (CCT) specimen has been used to evaluate the fatigue crack growth behaviour of the welded joints. Fatigue crack growth experiments have been conducted using servo hydraulic controlled fatigue testing machine at constant amplitude loading (R=0). A method has been proposed to predict the fatigue life of HSLA steel welds using fracture mechanics approach by incorporating influences of mis-match ratio (MMR) and post weld heat treatment (PWHT).