Cyclic hardening/softening behavior of 316L stainless steel at elevated temperature including strain-rate and strain-range dependence: Experimental and damage-coupled constitutive modeling. (March 2019)

• Record Type: Journal Article
• Authors: Xie, Xue-fang; Jiang, Wenchun; Chen, Jingkai; Zhang, Xiancheng; Tu, Shan-Tung
• Is Part Of: International journal of plasticity. Volume 114(2019:Mar.)
• Page Start: 196
• Page End: 214
• Publication Date: 2019-03
• Subjects: 316L stainless steel -- Elevated temperature -- Cyclic hardening/softening -- Damage-coupled cyclic constitutive model; Plasticity -- Periodicals; Plasticité -- Périodiques; Plasticity; Periodicals; 620.11233
• DOI: 10.1016/j.ijplas.2018.11.001
• Languages: English
• ISSNs: 0749-6419

Abstract

Abstract: In this study, the cyclic mechanical characters of 316L stainless steel at elevated temperature are extensively investigated by the experimental and cyclic constitutive models. The experiments include the monotonic tensile tests with different loading rates and the low cycle fatigue tests considering the effect of strain amplitudes, strain rates and loading sequences. The evolution of cyclic stress amplitudes, hysteresis loops and elastic modulus under various loading conditions are comprehensively analyzed. The experimental results show that the 316L steel at elevated temperature performs a typical three-stage cyclic mechanical response, i.e., initial hardening, subsequent saturation and final accelerated softening. The cyclic softening in both stiffness and flow stress is mainly caused by the nucleation of micro-voids or micro-cracks, and the subsequent coalesce and propagation. Furthermore, although the nearly rate-independent mechanical behavior is observed at monotonic tensile and first several fatigue cycles due to the DSA effect, the cyclic hardening/softening behavior shows a significant strain-rate and loading history dependence. Finally, inspired by the experimental observations and analyses, a damage-coupled cyclic elastic-viscoplastic constitutive model involving strain-range, strain-rate and loading history dependence is proposed to predict the complex cyclic behaviors of the material at elevated temperature. A hardening factor is incorporated into the Chaboche kinematic hardening equations to model the kinematic-induced hardening behavior. And the plastic strain memory surface and the maximum plastic strain rate are introduced to model the strain-range, strain-rate and loading history dependence of cyclic behavior. The proposed model is proved to effectively describe the complex evolution of not only cyclic stress amplitude but also hysteresis loops for the 316L steel at elevated temperature. Highlights: The cyclic response and fatigue mechanism for the 316L steel at room and elevated temperature were compared. The various tensile and LCF tests considering the effect of strain range, strain rate and loading sequence were carried out. The fatigue damage was determined experimentally, and incorporated into the cyclic elastic-viscoplastic constitutive model. The relationship between strain rate, DSA effect and cyclic behavior were investigated and realized by the proposed model. The proposed model can predict the evolution of not only cyclic stress amplitude but also hysteresis loops accurately.