Abstract
All-weld blocks of C-Mn steel were prepared by multipass submerged arc weld deposit, using different welding currents (500-750 A) and speeds (40-60 cm/min), filler wire of 4 mm diameter and a basic bonded type flux. The dendrite content of the weld blocks was estimated by quantitative metallography technique. The fatigue crack growth rate of the weld at LT direction of the block was evaluated by using C-T specimens and correlated with the area fraction of dendrite (Df) of the matrix. The increase in dendrite content of the matrix was found to reduce the crack growth rate by influencing significantly the material constant C and exponenet m of Paris law, da/dN=c(ΔK)m, where, 'a' is the crack length, 'N' is the number of loading cycle and ΔK is the stress intensity factor range. The modification of C and m with Df, was found to provide a satisfactory basis for the evaluation of fatigue crack growth rate of multipass C-Mn steel weld deposit having a given amount of dendrite.
