Body-thorough ultrahigh strength and ductility of austenitic 316L stainless steel by industry-applicable 3-axis stress-released impact

Austenitic stainless steel (SS) has been seeking a decent strength to match its other exceptional advantages such as remarkable corrosion resistance, antioxidant activity and good formability. High-strain-rate deformation techniques that are effective in strengthening SS surfaces, disappointingly, bring high risk of fracturing when applied to strengthen a bulk SS part. We demonstrate that a 3-axis room-temperature impact with intermediate annealing treatment can consistently promote the strength of bulk 316L SS to an unprecedented high level while posing no fracturing danger to the bulk SS. The impacts from multiple directions enable the smallest nanograins and a high volume of the thinnest twins in the sample, and in the meantime they inhibit the formation of martensite phase. The annealing treatment not only induces element segregation in the SS, which adds extra strengthening to the already significant grain/twin boundary strengthening, but also recovers the capability of the SS in storing dislocations upon deformation. Consequently, the 316L SS achieves an excellent ductility on the basis of the extraordinarily high strength. The steel also has a surprisingly low degree of hardness anisotropy, enhancing its applicability in complicated loading environments. Moreover, the novel process is realized with industry instruments and applicable for industries.