Dynamic Tensile Behavior of Prior Deformed AISI Type 304 Stainless Steel

Abstract Deformation in metastable austenitic stainless steel induces phase transformation of austenite to martensite when carried out at temperatures below M d . This study examines the influence of prior deformation at temperatures, below and above M d , on the dynamic tensile behavior of AISI type 304 SS. Prior deformation below M d (at 25 °C) as well as above M d (200 and 300 °C) improves the yield strength and ultimate tensile strength of the material. Remarkably, it is also observed that prior deformation at 25 °C to an equivalent strain $$(\overline{\varepsilon })$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>(</mml:mo> <mml:mover> <mml:mi>ε</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> &lt; 0.03 improves strength (22%) and ductility (21–37%) during subsequent tensile deformation at 200 and 300 s −1 . However, with a further increase in prior deformation strain ductility falls. In contrast, increasing levels of prior deformation at 200 and 300 °C, results in a continuous decrease in ductility. The observed tensile behavior is discussed in the context of strain induced martensitic transformation. Local strain field and strain rate evolution are analyzed using digital image correlation. Further, localized neck formation is examined using the images captured in-situ via a high-speed camera.