Fatigue life prediction of strength mis-matched HSLA steel welds

Welding of High Strength Low Alloy Steels (HSLA) involves usage of low, even, and high strength filler materials (electrodes) relative to the parent material depending on the application of the welded structures and the availability of filler materials. In the present investigation, an attempt has been made to predict the fatigue life of under-matched (UM), equal-matched (EM) and over-matched (OM) welded joints using a fracture mechanics approach by incorporating mis-match ratio (MMR). The base material used in this investigation is HSLA-80 steel of weldable grade. Shielded Metal Arc Welding (SMAW) has been used to fabricate single "V" butt joints. A Centre Cracked Tension (CCT) specimen has been used to evaluate the fatigue crack growth behavior of the welded joints. Fatigue crack growth experiments have been conducted using servo hydraulic controlled fatigue testing machine at constant amplitude loading (R=0). Effects of mis-match ratio (MMR) on fatigue crack growth behavior and fatigue life prediction of HSLA steel welds have been analyzed in detail.