Effect of Widmanstätten η phase on tensile shear strength of resistance spot welding joints of A286 superalloy

Abstract

This work aims to study the effect of Widmanstätten h phase on tensile shear strength (TSS) of resistance spot welding joints (RSW) of A286 superalloy subjected to post-weld high temperature aging treatment. The tensile shear test specimens were welded in the solution treated condition, and then subjected to six different post-weld aging treatments (at an aging temperature of 840°C for six different aging times). The ascast dendritic microstructure of the weld nugget and the austenite equiaxed-grain microstructure of the base metal have a different response to the post-weld high temperature aging treatment. Growth of Widmanstätten h phase in the weld nugget is faster than in the base metal. While in the base metal the Widmanstätten h phase precipitates into the grain, in the weld nugget precipitates at the interdendritic region because of the segregation of Ti towards the last-to-solidify interdendritic regions (studied by performing SEM/EDX analysis). Although the hardness increases with the presence of Widmanstätten h phase, the increase in hardness does not necessarily imply an increase in the experimental TSS.

Microstructural and mechanical characterization of powder-pack boronized Incoloy A286 superalloy

“…In addition, these alloys contain nominally 15 wt.% Cr, 25 wt.% Ni and and also a low quantity of different alloying additives [6]. It is reinforced by way of the spherical ordered face-centered cubic (FCC) g¢ Ni 3 (Al,Ti) precipitates [8,11]. It can be applied heat treatment on this superalloy simply.…”