| Abstract Scope |
Welding occurs at various stages of steel castings such as production welding in foundry repair, fabrication welding of casting to casting or casting to wrought, and field repair welding. Although there are recommended practices on welding of carbon and low alloy steel castings in the literature, there is a lack of effective analysis approach along with necessary data for quantitative assessment of fatigue life of welded cast steels for production welding. Difficulties in such assessment arise from a number of factors including weld discontinuities and heat-affected zone. In this study, the fatigue life of a high-strength steel casting weld was studied. Experimentally, an 8630 cast steel, with a yield strength of 980 MPa (or 140 ksi), was welded by flux cored arc welding with an undermatching filler metal (yield strength 700 MPa or 100 ksi). After welding, the plates were subjected to a 3-hour-long post weld heat treatment at 510 C (950 F). The weld was qualified via tensile testing and side bend testing. Moreover, fatigue testing was done on cross-weld specimens at R-ratio of 0.1. For fatigue analysis, a fracture-based approach combined with strain-based methods was developed. Specifically, the approach starts with Neuber’s rule and the Ramberg-Osgood equation for deformation plasticity. The fatigue life is then estimated using the Smith-Watson-Topper method where the material fatigue properties such as fatigue strength coefficient and fatigue ductility exponent were determined from the fatigue testing results. The approach was validated against existing literature data of fatigue testing of T-shaped weld samples. The effect of undermatch filler metal on weld fatigue life was discussed. |