Fracture resistance of a steel weld joint under fatigue loading

Abstract

Fatigue crack growth tests are performed to examine the variation of crack growth resistance in the weld joint of AH36 TMCP steel. Plate materials are joined together by single-pass SEGARC welding. Residual stresses are removed by heat treatment to focus the study on the microstructural effect. Single edge notch specimens are made from the welded plate with cracks at varying distances from the fusion line. Crack growth tests are performed under R = 0 cyclic loads. Stress intensity factors are determined based on the measured strain distribution at the remote boundary. The resistance to crack initiation and growth is found to increase from the base metal toward the weld metal as the contents of fine acicular ferrite becomes larger. The variation is, however, rather small and may be practically overlooked. The fracture toughness is found lowest in the heat affected zone near the fusion line where coarse bainite grains are found. (C) 2000 Elsevier Science Ltd. All rights reserved.