Probing local difference of martensite formation: a study on localized deformation modes in drawn 304H stainless steel wires

Abstract

304H austenitic stainless steel wire was investigated, emphasizing microstructural deformation, martensite phase transformation, and residual magnetic properties during drawing. Utilizing several microstructural observation techniques, the volume fraction of martensite, modes of grain deformation in distinct regions, and the phase relationship between austenite and martensite were comprehensively characterized. In addition, a finite element simulation with representative volume elements specific to different zones also offers insights into strain responses during the drawing process. Results from the first-pass drawing reveal that there exists a higher volume fraction of martensite in the central region of 304H austenitic stainless steel wire compared to edge areas. This discrepancy is attributed to a concentrated presence of shear slip system {111}<110>γ crystallographic orientation, primarily accumulating in the central region obeying the Kurdjumov–Sachs path. Subsequent to the second drawing pass, the cumulative shear deformation within distinct regions of the steel wire became more pronounced. This resulted in a progressive augmentation of the volume fraction of martensite in both the central and peripheral regions of the steel wire. Concurrently, this led to a discernible elevation in the overall residual magnetism of the steel wire.