Characterisation of graded austenitic stainless steel sheet fabricated by stair rolling treatment

Abstract

We propose a novel processing technique called Stair Rolling Treatment (SRT) to generate a graded sheet with a functionally graded microstructure along its longitude. The SRT process generates a longitudinal plastic strain gradient by the cold rolling of a longitudinally variable-thickness plate. Microstructural and mechanical characterisation of the 304L stainless steel SRT sheets, are performed by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron channelling contrast imaging (ECCI), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) techniques, microhardness measurements, and uniaxial tensile tests. Mechanical characterisations show that the gradients of phase and grain size lead to mechanical incompatibility and hence non-uniform stress and strain during tensile tests. The annealed SRT sheet samples demonstrate a good combination of strength and ductility.