Low-Cycle Fatigue Life Prediction of 10CrNi3MoV Steel and Undermatched Welds by Damage Mechanics Approach

W Song,Yu Fan,X Liu,Xiaolei Xia,F Berto,Jie Xu,Duanhu Shi,Feng Yang,Di Wan

doi:10.3389/fmats.2021.641145

Abstract

Welding of steel is a technique frequently used in practical engineering applications; however, their mechanical performance is strongly dependent on the physical metallurgical status of the weldments. In the present study, fully reversed, strain-controlled low-cycle fatigue (LCF) tests were conducted on 10CrNi3MoV steel and its undermatched weldments with strain amplitudes varying from Δε = ±0.5 to ±1.2%. Both base metal and weldments exhibited softening behavior at the beginning of the cyclic stage. Numerical investigations of cyclic stress–strain evolutions of the materials have been studied by the cyclic plastic model considering nonlinear hardening. The continuous damage mechanics (CDM) theory based on the experimental hysteresis stress–strain energy concept was employed to illustrate LCF failure, including damage initiation and deterioration. The damage mechanics approach calibrates the material parameters from the measured fatigue life for initiation and growth stages. Afterward, the combination of material cyclic plastic parameters and damage parameters was implemented to predict the LCF life. Good agreement can be observed between the experimental results and the FE results based on the CDM approach. Finally, the damage evolution of the materials under different strain amplitudes by this approach was assessed.

Highlights

High/ultrahigh-strength steel has become an increasing choice for the manufacturing industries of machinery, marine structures, offshore structures, bridge structures, and other engineering facilities with excellent strength-to-self weight ratios and mechanical properties (Miki et al, 2002; Feng and Qian, 2018b; Ahola et al, 2019b; Chung et al, 2020)
While the following literature survey has been carried out to assess the fatigue properties of high-strength steel by experimental and numerical simulation approaches for different engineering fields, a series of strain-controlled low-cycle fatigue (LCF) experiments of highstrength steel S550 under different strains were analyzed based on cyclic plastic theory and continuous damage mechanics (CDM) (Feng and Qian, 2018a)
To predict the material total fatigue life, we adopt the continuum mechanics theory proposed by Darveau (Darveau, 2002) and Lau et al (Lau et al, 2002) for the LCF calculation in ABAQUS

Summary

INTRODUCTION

High/ultrahigh-strength steel has become an increasing choice for the manufacturing industries of machinery, marine structures, offshore structures, bridge structures, and other engineering facilities with excellent strength-to-self weight ratios and mechanical properties (Miki et al, 2002; Feng and Qian, 2018b; Ahola et al, 2019b; Chung et al, 2020). In terms of the LCF regime of material and components, related fatigue indicators are generally focused on the strain and energy fatigue characteristics due to the local plastic deformation These parameters cannot demonstrate fatigue damage’s evolution with the increases of loading cycles by static mechanical analysis. Equation 12 can be used to estimate the total fatigue life when the material parameters are given by the combination of fatigue damage initiation and evolution These four damagerelated parameters can be fitted from experimental data under different stress ratios

FE RESULTS AND DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT