from the conferences organized by TANGER Ltd.
In this study, an AISI 304L stainless steel was produced with a nanocrystalline structure using a high-energy mechanical alloying technique with Y-element and nanoscale B4C additions and annealed at 900 °C for 1h. Structural changes and mechanical properties were investigated using X-ray diffraction analysis, Archimedes density and microhardness test, respectively. The results showed that the crystal structure of 304L stainless steel, which has a face-centered cubic (fcc) lattice at equilibrium, transforms into martensite with a body-centered cubic (bcc) lattice due to the severe plastic deformation induced by high-energy mechanical alloying. Upon thermal exposure, a reverse martensite-to-austenite phase transformation was triggered. The relative density of 304L steel improved with the addition of Y and B4C. A significant increase in hardness was observed after mechanical alloying and attributed to the formation of a nanocrystalline structure and deformation-induced martensite. However, annealing led to a decrease in hardness, which was associated with grain growth. This reduction in hardness was less pronounced in 304L containing solute elements and ceramic particle additions. Evaluation of the hardness changes together with XRD peak broadening results indicated that solute addition and ceramic particle reinforcement play an important role in restricting grain growth.
Keywords: Stainless steels, mechanical alloying, thermal stability, martensitic transformation© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.