Study of the effect of Accumulative Angular Drawing deformation route on grain refinement in 304L stainless steel

Abstract

Stainless steel grades – both austenitic and ferritic – find a wide critical applications due to their superior properties such as high strength, excellent corrosion resistance and good biocompability. Manufacturing e.g. medical equipment and implants made of stainless steel grades often involves wire drawing processes. Further improvement of mechanical properties requires more research in the field of grain refinement, which is the main strengthening mechanism, that does not decrease the ductility and toughness. In the present work, capabilities of grain refinement in 304 austenitic stainless steel using recently developed technology of Accumulative Angular Drawing (AAD) was studied. Focus was put on the analysis of the influence of process parameters on inhomogeneity of microstructure and related mechanical properties. The AAD process uses the effect of complex deformation mode and strong strain accumulation to obtain a controlled level of heterogeneity of the microstructure and the resulting properties. In the current work, wire rods of the 304L stainless steel were drawn using linear, stepped and cranked drawing dies arrangements. The main goal of this work was aimed at understanding the effect of deformation conditions on the microstructure and properties of 304 stainless steel drawn wires, by studying the mechanical properties after drawing (hardness, tensile strength) and microstructure evolution during the AAD process. The effects of complex deformation modes and strong strain accumulation were studied in the light of possible grain refinement and mechanical properties.