Mechanical Properties and Defective Effects of 316LN Stainless Steel by First-Principles Simulations

In current International Thermonuclear Experimental Reactor (ITER) design, the 316LN austenitic stainless steel (316LN SS) is used for first-wall/blanket structures. Thus, it is necessary to study the fundamental mechanical properties and irradiation effect of 316LN SS. A random solid solution model of Fe-Cr-Ni-Mn-Mo-Si alloy is used for describing 316LN SS. Using first-principles approaches, the elastic constants and ideal strength of the alloy were calculated. Such alloy exhibits good ductile behavior according to the theoretical values of Cauchy pressure and ratio of bulk modulus and shear modulus. Within the 256-atom supercell, inclusion of single vacancy defect further enhances the ductility of the alloy, and the existence of interstitial (Fe, H, He) atoms enhances the Young's modulus.