5th International High Manganese Steel Conference - HMNS 2022

Abstract: Advanced austenitic stainless steels are a group of austenitic stainless steels with a nickel content near or higher 30 wt% and a pitting resistance equivalent number (PREN) is near or higher than 40. They are widely used in the oil-gas and chemical industries. Due to high Ni content, these alloys are costly. Mn and N are two low cost alloying element for austenite stability. In this study, influence of Mn and N on mechanical properties and corrosion resistance of advanced austenitic stainless steels are discussed. Unexpectedly, a combination Mn (about 6 wt%) and N (about 0,25 wt%) can greatly increase both strength and elongation of the advanced steels. When tensile-tested at a cryogenic temperature, the strengths and elongations of the steels are further increased. EBSD and ECCI studies show that addition of manganese and nitrogen has increased amount of nano deformation twins in the steels at RT. At the cryogenic temperature, much more nano deformation twins in the steels can be observed. This indicates that twin induced plasticity, TWIP, has led to high elongations in the steels. These phenomena have been explained by the stacking fault energy and the critical stress for deformation twinning evaluated by ab initio simulation at RT and cryogenic temperature. The influence of Mn and N on the corrosion properties of the steels has also been studied with ASTM G-150. A pitting resistance equivalent number (PREN) with Mn is used to predict the corrosion properties. This paper will increase our understanding for the development of high performance and low cost advanced austenitic stainless steels.