Low temperature mechanical properties of 316L type stainless steel after hydrostatic extrusion

Abstract

316L-type stainless steel is commonly used in fusion devices. Its mechanical properties at cryogenic temperatures, for rolled or forged products possessing a grain size of tens of micrometers have been widely reported. In this paper we present the properties of this steel after multi-pass hydrostatic extrusion (HE), which brought about significant grain refinement to the nanometer scale. Such grain refinement of 316L-type stainless steel would be expected to improve the yield and ultimate tensile strength and may also result in a better resistance to irradiation. The microstructure of the HE processed samples was determined by electron microscopy and the mechanical properties evaluated by its microhardness under a load of 200 g and by tensile tests at room temperature and after immersion in liquid nitrogen. The observed improvements of the mechanical properties are discussed in terms of the microstructural changes arising from the hydrostatic extrusion.