Uniaxial Ratcheting Behavior of Stainless Steels: Experiments and Modeling

Abstract

Based on a series of uniaxial ratcheting tests on 304 and 1Cr18Ni9Ti stainless steels carried out under cyclic stressing at room temperature and elevated temperature, the concepts of unitary ratcheting stress and ratcheting stress threshold were presented and a set of methodological system was developed to be used for modeling evolution of ratcheting strain of the materials under uniaxial stress at room temperature as well as for simulating saturated ratcheting (SR) constitutive behavior of the materials at elevated temperature. The presented systemic methods can overcome difficult problems to describe ratcheting deformation from traditional dualistic stress control. Both the ratcheting-evoluted model and SR constitutive model have better precision to regress experimental data and are accessible to engineering application due to easy establishment in equation.

Ratcheting in pressurized pipes and equipment: A review on affecting parameters, modelling, safety codes, and challenges

“…27,183 The present section focuses on the phenomenological models developed to assess ratcheting of components undergoing asymmetric load cycles. 21 Cai et al 27,183 defined ratcheting strain as a function of maximum and minimum strains (ε max , ε min ) and the corresponding loading and reloading stresses as σ L and σ R , respectively. 18,21,184 Analogous to creep phenomenon, the stages of ratcheting as illustrated in Figure 2 expand over life cycles.…”

“…183 Coffin 185 presented a simple relation to define ratcheting strain based on load cycles and material properties. 183 Coffin 185 presented a simple relation to define ratcheting strain based on load cycles and material properties.…”

“…Parametric equations have been structured based on the applied mean and amplitude of stresses, cyclic hardening or softening behaviours, and number of cycles. 27,183 The present section focuses on the phenomenological models developed to assess ratcheting of components undergoing asymmetric load cycles. Experimental evidences have supported triphasic response of ratcheting in engineering alloys.…”

“…Beyond stage II, the third stage corresponded to a suddenly raised ratcheting progress and strain rate leading to failure. 21 Cai et al 27,183 defined ratcheting strain as a function of maximum and minimum strains (ε max , ε min ) and the corresponding loading and reloading stresses as σ L and σ R , respectively.…”

“…where α, α r , α T , k r , k T , and σ 0.2 are material constants which are determined from the experimental ratcheting tests. 183 Coffin 185 presented a simple relation to define ratcheting strain based on load cycles and material properties. The ratcheting strain ε r in this model was found highly related to material ductility and fatigue life of cyclically loaded samples:…”