Risks Associated with the Use of Stainless Steel X10CrNi18-8 Under Combined Impact-Oscillatory Loading and Cryogenic Cooling

The study establishes key patterns in the influence of pre-applied impact-oscillatory loading (IOL) of varying intensity—realizing dynamic non-equilibrium processes (DNP)—in liquid nitrogen on the mechanical properties and structural state of stainless steel X10CrNi18-8. Static tensile deformation was investigated at room temperature following impulsive strain levels of εimp = 0.06–2.69%. A wave-like mechanical response of the steel to DNP was observed within this εimp range, most pronounced at εimp = 0.11% and εimp = 2.69%. After DNP at εimp = 0.11%, despite a maximum increase in ultimate strength by 5.25%, the relative elongation of the specimen increased to 10.3%. The scatter in ultimate tensile strength specimens across all loading regimes was within 6.38%, while the variation in ductility reached up to 21.25%. In contrast, after εimp = 2.69%, the stress–strain diagram resembled that of the steel in its initial state. Metallophysical investigations and X-ray diffraction analysis were conducted to explain the observed effects. At εimp > 2.7%, the high-strength but low-ductility X10CrNi18-8 steel undergoes brittle failure under impulsive loading. At the same time, the total fraction of the more brittle martensitic phase in the steel microstructure reaches approximately 22%.