On specimen design for high cycle fatigue testing of welded joint

Axially push-pull fatigue tests of a low-strength Cr-Ni-Mo-V steel welded joint using cross-weld specimens with two types of sampling, i.e., weld metal centered and heat-affected zone centered, were conducted up to 5 x 10(7) cycles at room temperature and 300 degrees C. Fatigue strength of heat-affected zone centered specimen was higher due to dynamic strain aging at weld metal at 300 degrees C and a locally mismatched deformation around heat-affected zone. The failure location varied as a result of mismatched deformation, structural soft zone, and micro-defects. The sampling dependence implied for a proper fatigue design and assessment of welded structures.