An approach for identifying the deformation-induced strain from tensile tests and x-ray diffraction measurements

Abstract

ABSTRACT Non-uniform plastic deformation and phase transformation introduce residual stress (RS) in a material. The present study focuses on the influence of tensile strain on RS development in 304L austenitic stainless steel, wherein strain-induced martensite (SIM) transformation influences deformation behaviour. Room temperature tensile tests were interrupted at various tensile strains between the material yield and ultimate tensile strength at 5.21 × 10−4 and 1.3 × 10−2 s−1 strain rates. Microstructural characterisation of as-received and deformed samples by electron backscatter diffraction provides evidence of SIM formation and shear bands. Analysis of tensile flow and work hardening behaviour is discussed in correlation to the microstructural and dislocation density variations. In addition, RS in the austenite and martensite phases was measured using the x-ray diffraction method, and the RS balance that occurs between the longitudinal and transverse components and the two phases after tensile deformation is presented. It is shown that a combined analysis of RS and x-ray diffraction peak width could be utilised to find the deformation level in tensile fractured, press brake bent, and roll bent samples.