Constitutive gradients and pore tolerance in two weldments

The mechanical constitutive behavior of welded components is difficult to characterize at any size scale, but particularly challenging in the case of sub-millimeter welds such as produced by laser welding. Recently emerging digital image correlation (DIC) techniques provide a means for extracting local constitutive response. The tensile stress-strain response of laser welded austenitic 304L is evaluated in the present study. Weld fusion zones were found to have slightly higher yield strengths than the corresponding basemetal, and retained significant ductility (∼45%). In this ductile, flaw tolerant stainless steel, the local weld ductility was essentially unaffected by the presence of weld-root porosity which was induced only by pulsed laser welding. In contrast, in a parallel study on the local constitutive properties of a welded Ni-Gd-Mo-Gd alloy with much less macroscopic ductility, the presence of weld root porosity was found to localize strain only in the vicinity of the largest pores, causing premature failure at low macroscopic strains. Copyright © 2006 by ASME.