Fatigue Crack Initiation and Propagation in High Yeild-Strength Steel Weld Metal

Full penetration, double-vee butt welds with reinforcement removed have been fabricated using a high-yield-strength steel, HY-130. Various filler metals and welding techniques were used. Most welds contained intentionally incorporated weld discontinuities such as slag, lack of fusion and /or porosity. Fatigue specimens were cut from these welds and tested in zero-to-tension, axial fatigue. The point at which a fatigue crack began to propagate within the specimen was determined by radiographic measurements. The fatigue life of a specimen could therefore be separated into two parts-that portion spent in initiating a fatigue crack and that spent in fatigue crack propagation. The influence of flaw size and geometry upon the crack propagation portions of the fatigue life was found to be large and to depend upon the thickness of the member. The results of these studies were found to be in good agreement with the fatigue lives predicted on the basis of a fracture mechanics analysis.ASM