Abstract
Effect of welding tensile residual stresses on fatigue crack propagation in low propagation rate region (low ΔK region) was studied experimentally. Material used was steel of 800 MPa in tensile strength. Specimens were center-cracked-plates and consisted of three kinds; specimens without weld, specimens with longitudinal weld (as weld), specimens with longitudinal weld (stress relieved). Major results obtained are summarized as follows:
(1) Tensile residual stresses decreased the threshold value of ΔK.
(2) When tensile residual stresses were large, the threshold value of ΔK was unique and independent of stress ratio.
(3) Effect of residual stresses could be dealed with as effect of mean stresses.
