Fabrication of Gradient Semi-solid 9Cr18 Stainless Steel and the Microstructure Evolution

In this paper, a semi-solid thixoforging set-up was designed based on Gleeble3500 thermomechanical machine. 9Cr18 thixoforging component was fabricated and the microstructure evolution was investigated. The results showed that the 9Cr18 semi-solid billet could demonstrated thi-xotropic behavior after the breakdown of solid skeleton and load decreased with the deformation during thixotropic stage. Gradient microstructure could be obtained for the 9Cr18 thixoforging specimen. An obvious solid/liquid interface existed near the edge area of thixoforging specimen. Eutectic structure with plenty of carbide could be seen outside the solid/liquid interface. Solid particles were mainly retained at the inner area. 9Cr18 thixoforging specimen demonstrated unique microstructure evolution. The solid particles at the inner area mainly showed austenite microstructure with excellent deformation behavior, while the hard M7C3 carbides existed at surface eutectic layer. This microstructure characterization contributed to the properties of tough center and hard surface. © 2021, Materials Review Magazine. All right reserved.