| Summary: | Deformation-induced martensitic transformation as the basis of a hardening process is dependent, among others, on the stress state. In applications such as cryogenic cutting, where a hardened martensitic subsurface can be produced in metastable austenitic steels, different stress states exist. Furthermore, cutting typically occurs at high strain rates greater than <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mn>10</mn><mn>3</mn></msup></semantics></math></inline-formula><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi mathvariant="normal">s</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></semantics></math></inline-formula>. In order to gain a deeper insight into the behavior of a metastable austenitic steel (AISI 304) upon cryogenic cutting, the influence of high strain rates under different loading conditions was analyzed. It was observed that higher strain rates lead to a decrease in the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>α</mi><mo>′</mo></msup></semantics></math></inline-formula>-martensite content if exposed to tensile loads due to generated adiabatic heat. Furthermore, a lath-like <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>α</mi><mo>′</mo></msup></semantics></math></inline-formula>-martensite was induced. Under shear stress, no suppression of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>α</mi><mo>′</mo></msup></semantics></math></inline-formula>-martensite formation by higher strain rates was found. A lath <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>α</mi><mo>′</mo></msup></semantics></math></inline-formula>-martensite was formed, too. In the specimens that were subjected exclusively to compressive loading, almost no <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>α</mi><mo>′</mo></msup></semantics></math></inline-formula>-martensite was present. The martensitic surface generated by cutting experiments showed deformation lines in which <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>α</mi><mo>′</mo></msup></semantics></math></inline-formula>-martensite was formed in a wave-like shape. As for the shear specimens, more <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>α</mi><mo>′</mo></msup></semantics></math></inline-formula>-martensite was formed with increasing strain rate, i.e., force. Additionally, magnetic etching proved to be an effective method to verify the transformation of ferromagnetic <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>α</mi><mo>′</mo></msup></semantics></math></inline-formula>-martensite.
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