In-Situ Measurements of Load Partitioning in a Metastable Austenitic Stainless Steel: Neutron and Magnetomechanical Measurements

Abstract

In order to construct physically based models of the mechanical response of metastable austenitic steels, one must know the load partitioning between the austenite and the strain-induced martensitic phases. While diffraction-based techniques have become common for such measurements, they often require access to large facilities. In this work, we have explored a simple magnetic technique capable of providing a measure of the stresses in an embedded ferromagnetic phase. This technique makes use of the coupling between the elastic strain and the magnetic response of the $\alpha^{\prime}$-martensite in an austenitic stainless steel undergoing straining. The magnetic technique proposed here is compared to neutron diffraction measurements made on the same material and is shown to give nearly identical results. The resulting predictions of the load partitioning to the $\alpha^{\prime}$-martensite phase suggest that $\alpha^{\prime}$ deforms in a complex fashion, reflecting the fact that the microstructure is progressively transformed from austenite to martensite with straining. In particular, it is shown that the apparent hardening of the $\alpha^{\prime}$-martensite suggests elastic deformation as an important source of high macroscopic work-hardening rate in this material.