Adiabatic Heating of Austenitic Stainless Steels at Different Strain Rates

This work focuses on the effect of strain rate on the mechanical response and adiabatic heating of two austenitic stainless steels. Tensile tests were carried out over a wide range of strain rates from quasi-static to dynamic conditions, using a hydraulic load frame and a device that allowed testing at intermediate strain rates. The full-field strains of the deforming specimens were obtained with digital image correlation, while the full field temperatures were measured with infrared thermography. The image acquisition for the strain and temperature images was synchronized to calculate the Taylor–Quinney coefficient (β). The Taylor–Quinney coefficient of both materials is below 0.9 for all the investigated strain rates. The metastable AISI 301 steel undergoes an exothermic phase transformation from austenite to α’-martensite during the deformation, which results in a higher value of β at any given strain, compared to the value obtained for the more stable AISI 316 steel at the same strain rate. For the metastable 301 steel, the value of β with respect to strain depends strongly on the strain rate. At strain rate of 85 s⁻¹, the β factor increases from 0.69 to 0.82 throughout uniform elongation. At strain rate of 10⁻¹ s⁻¹, however, β increases during uniform deformation from 0.71 to a maximum of 0.95 and then decreases to 0.91 at the start of necking.