The Effect of W addition on Simulated Heat - affected Zone Impact Toughness in 25Cr - base Super Duplex Stainless Steel

Abstract

The effect of partial replacement of Mo with W on the simulated heat-affected zone (HAZ) toughness of 25Cr-base super duplex stainless steels has been investigated, All the simulated alloys exhibited a decrease in toughness at fast cooling due to high proportion of ferrite and intragranular precipitates. Impact toughness also decreased at slow cooling, Δt_(12/8)=270sec, because of large matrix ferrite grain size despite higher austenite content. Peak impact toughness level was observed at cooling time of 33sec for all the alloys. It was also found that the substitution of W for Mo produces high impact toughness at all cooling conditions resulting from the increased austenite content, decreased intragranular precipitates and smaller ferrite matrix grain size. In conclusion, the addition of W has favorable effects on HAZ toughness of 25Cr-base super duplex stainless steels.