Henry Granjon Prize Competition 2012 Winner Category B: “Materials Behaviour and Weldability” Influence of the [creq+Nieq] Alloy Level on the Transition Between Solidification Modes in Austenitic Stainless Steel Weld Metal

Abstract

It is well known that primary austenitic solidification modes [A, AF] are related to hot cracking susceptibility in the welding of austenitic stainless steels; therefore the transition between primary austenitic solidification mode [AF] and primary ferritic solidification mode [FA] is of utmost importance and traditionally has been related to a critical Creq /Nieq ratio. This paper presents the experimental results obtained when analysing the effect of alloy level on the transition between solidification modes in austenitic stainless steel weld metals. With this aim, two series of compositions of austenitic stainless steel samples were prepared using an electric arc remelting furnace, keeping the overall alloying composition at two constant levels of [Creq+Nieq] = 30 wt% and [Creq+Nieq] = 40 wt% while changing the Creq/Nieq ratio from 1.22 up to 2.00 in each series. The experimental results show that for an alloy level of [Creq+Nieq] = 30 wt%, the critical Creq/Nieq ratio for the [AF]/[FA] transition takes place between 1.38 and 1.55, while in case of [Creq+Nieq] = 40 wt% the critical Creq/Nieq ratio takes place between 1.28 and 1.32, which is lower in value and narrower in range than the values obtained for the lower alloyed series. A comparison between these experimental results and other authors’ previous research is presented. Results reveal the importance of the alloy level [Creq+Nieq ] as a key parameter in the transition between solidification modes.