Transient Thermal Stresses and Residual Stresses of 13Cr Cast Steels during Welding

Abstract

13 Cr cast steels, which are martensitic stainless steels, have been shown that the sensitivity of weld cracking was remarkable. However, their properties of residual stress distributions are not made clear. From the standpoint of confirmation of welding conditions and strength assessment for weldments, it is required to investigate the distributions of welding residual stresses.
Therefore, transient thermal stresses of weld heat-affected zone about 13 Cr cast steels, SCS5 are investigated by a round bar which both ends are fixed and subjected to a thermal cycle simulating weld heat. The results indicate that the effect of transformation expansion on residual stress distribution are remarkable in comparison with carbon steels, SM41B. The residual stress in a region heated above A_c1 transformation point become compressive stress of about -100 MPa and yet the peak residual stress become about 400 MPa in a region out of the HAZ. And also, one-dimensional analysis method to conveniently evaluate residual stresses is presented. The effects of preheat temperature on residual stresses are discussed and the estimated residual stresses by the convenient method showe good agreement with the experimental results of butt welded joints.