Mechanical Response of Stainless Steels at Low Strain Rate.

The deformation behavior of the selected stainless steels (UNS S31603, UNS S32205, UNS S32550 and UNS S32760) was evaluated at strain rates ranging between 10^-2 and 10^-7 s^-1. Microstructural evaluation was conducted using optical and scanning electron microscopy, electron backscattered diffraction and x-ray diffraction. The total strain at fracture remained approximately constant as the strain rate increased from 10^-7 to 10^-3 s^-1. Further increase in strain rate above 10^-3 s^-1 resulted in relatively lower strain. The strain rate sensitivity of each steel decreased with increasing strain. Also, the strain hardening rate and exponent of the alloys increased with decreasing strain rate. Post-deformation microstructure evaluation on UNS S31603 specimens showed slip, twinning and martensitic transformation, while the duplex alloys exhibited slip, twinning with less noticeable martensitic transformation. Fractographic examination after tensile test indicates an increase in dimple diameter with strain rate and subsequent decrease in dimple density. [ABSTRACT FROM AUTHOR]