Assessment of some factors influencing the fatigue life of strength mis-matched HSLA steel weldments

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 material. In this investigation an attempt has been made to assess the influences of mis-match ratio (MMR), post-weld heat treatment (PWHT) and notch location on fatigue life of HSLA steel welds. Shielded metal arc welding (SMAW) process has been used to fabricate the butt joints. Centre cracked tension (CCT) specimen has been used to evaluate the fatigue life of welded joints. Fatigue experiments have been conducted using servo hydraulic controlled fatigue testing machine at constant amplitude loading (R=0). Design of experiments (full factorial design) concept has been used to optimise the number of experimental conditions. A procedure has been developed to assess and optimise the above chosen factors to attain a maximum fatigue life value by incorporating (i) response table and response graph, (ii) normal probability plot and (iii) analysis of variance (ANOVA) techniques.