A simple unified theory for the cyclic deformation of metals at high temperature

• Published in: Acta mechanica 1996-01, Vol.118 (1-4), p.135-149
• Main Authors: LU, Z. K, WENG, G. J
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: structure, mechanical and thermal properties; Creep; Deformation and plasticity (including yield, ductility, and superplasticity); Exact sciences and technology; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Metals. Metallurgy; Physics
• ISSN: 0001-5970; 1619-6937
• DOI: 10.1007/BF01410513

A simple constitutive equation involving only six material constants has been developed to describe the high temperature deformation of metals over a wide range of stress and temperature. The model involves a drag stress and a back stress, along with their evolution equation. A new concept has been introduced to connect the growth behavior of these two internal state variables so as to reduce the number of material constants required in the description under cyclic loading conditions. It is demonstrated that this simple model can adequately describe the stress-strain behavior of a 617 nickel-base superalloy over three different orders of strain rate, and up to 900 deg C. It can also provide the cyclic hardening behavior and stable hysteresis loop under a strain-controlled loading, and the strain-ratchetting under an off-axis, stress-controlled loading, among others. The influence of stress and temperature on creep, and the influence of mechanical and thermal cycling on the creep strain accumulation can all be studied with this set of simple constitutive equations.