Direct tuning of the microstructural and mechanical properties of high-alloy austenitic steel by electron beam melting

Abstract

In the present work austenitic stainless steel X2CrMnNi16-7-9 was additively manufactured using electron beam melting (EBM) technique. In order to reach the highest work of deformation processing parameters such as scan speed, beam current and volume energy were varied. Different properties of manufactured samples, including chemical composition, density, roughness, yield and tensile strength, ductility, grain morphology, texture, and phase composition were thoroughly examined by means of SEM, EDX, EBSD, tensile testing, Archimedes and other methods. The correlation between the parameters was analysed and optimal processing settings allowed to reach work of deformation up to 39 GPa with remarkable elongation up to 110%. It was also found that tuning of the Mn evaporation during EBM by varying the beam energy resulted in the change of stacking fault energy and martensitic transformation temperatures of the steel. This led to the change of the austenite stability and plasticity mechanisms, such as the occurrence of deformation induced martensite in the initially TWIP steel. Comparison of phase diagrams of the studied X2CrMnNi16–7–9 steel and similar X5CrMnNi16-6-6 steel has proven that the reason for in situ EBM grain refinement in the latter one is the presence of primary bcc phase field. • Manipulation of Mn content via EBM can be used to change CrMnNi steel properties. • Grain refinement during EBM of CrMnNi steel is due to bcc to fcc transition. • CrMnNi steel with 39 GPa·% work of deformation and 110% strain is produced by EBM. • Optimal processing window for EBM production of X2CrMnNi16-7–9 steel is revealed.