Weld microstructure development and properties of precipitation-strengthened martensitic stainless steels

The weld microstructural evolution, mechanical properties and solidification cracking susceptibility of three precipitation-strengthened martensitic stainless steels - PH 13-8 Mo, Custom 450 and 15-5 PH - were investigated. Liquid tin quenching of gas tungsten are welds revealed that all th ree welds solidified as single-phase ferrite with a high degree of microsegregation. However, during further solidification and cooling almost complete homogenization occurred as a result of solid-state diffusion. The welds in all three alloys exhibited good resistance to solidification cracking and generally exhibited tensile and impact properties similar to those of the base metal. However, in almost all cases, the weld Charpy impact energies were somewhat less than those of the base metals. The cracking behavior and mechanical properties are discussed in terms of microstructural evolution.