Constitutive equations to predict high temperature flow stress in a Ti-modified austenitic stainless steel

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2009-01, Vol.500 (1), p.114-121
• Main Authors: Mandal, Sumantra, Rakesh, V., Sivaprasad, P.V., Venugopal, S., Kasiviswanathan, K.V.
• Format: Article
• Language: English
• Subjects: Applied sciences; Austenitic stainless steel; Compensation of temperature and strain rate; Constitutive equation; Elasticity. Plasticity; Exact sciences and technology; Flow stress; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2008.09.019

The experimental stress–strain data from isothermal hot compression tests, in a wide range of temperatures (1123–1523 K) and strain rates (10 −3–10 2 s −1), were employed to develop constitutive equations in a Ti-modified austenitic stainless steel. The effects of temperature and strain rate on deformation behaviors were represented by Zener-Holloman parameter in an exponent type equation. The influence of strain was incorporated in the constitutive analysis by considering the effect of strain on material constants. The constitutive equation (considering the compensation of strain) could precisely predict the flow stress only at 0.1 and 1 s −1 strain rates. A modified constitutive equation (incorporating both the strain and strain rate compensation), on the other hand, could predict the flow stress throughout the entire temperatures and strain rates range except at 1123 K in 10 and 100 s −1. The breakdown of the constitutive equation at these processing conditions is possibly due to adiabatic temperature rise during high strain rate deformation.