Abstract: The weldmatching behaviours in yield strength for welded joints of several steels under static, dynamic and fatigue loading conditions were studied respectively. The distributions of residual stresses for different ratios of weldmatching were measured also. The conclusions were drawn tihat either for initiation under static and dynamic loading, or for propagation properties the effect of overmatching of weldmetal in yield strength was beneficial for investigated cases; the values of ΔK (th), I. e. the propogation threshold are equal each other in the two kinds of welded joints of A131 and A537 steels welded with the same eletrode LB52NS, and notable difference wasn't found for da/dN of the same two kinds of steel welded joints in fatigue or corrosion fatigue tests; the residual stresses in weldmetal of A131 welded joint was somewhat higher than that of A537 welded joint.

Key words: Crack, Fatigue, Residual stress, Welded joint