Effect of Burr Grinding on Fatigue Strength of Steel Butt-Welded Connections

Among assembling methods, welding is most widely used in various industries. During the welding operation, material is heated to a temperature above the melting point and melted material forms a weld pool. This leads to the formation of tensile residual stresses in the weld toe. In this paper, effect of burr grinding technique on fatigue strength of butt-welded joint has been evaluated. Burr grinding is one of the weld geometry modification methods that with removing small crack-like defects at the weld toe and increasing weld toe radius leads to reduction of stress concentration factor (SCF) and improvement of fatigue strength of weld. Also, the finite element simulation was performed by using ABAQUS software and stress concentration factor was chosen as a criterion. This factor was calculated using analytical and numerical methods for samples before and after grinding. Burr grinding procedure on welded samples was done using an electric grinder and different conical burrs. Burrs with different radii have been selected in order to provide a better comparison. Fatigue life of samples before and after grinding was determined by fatigue tests under constant amplitude loading. The results show ۴۳.۷۲ percent improvement in stress concentration factor and ۵۰.۶۱ percent improvement in fatigue life of samples. In experimental study, the best result belongs to grinding with a ۳ mm tapered burr leading to an improvement of ۵۰.۶۱% in fatigue life while grinding with ۱ mm tapered gives the worst result of ۸.۸۸% improvement in fatigue life.

Keywords:

Burr grinding , Fatigue strength , Stress concentration factor butt weld