Low Cycle Fatigue Life Prediction for Hydrogen-Charged HRB400 Steel Based on CPFEM

Area of Science:

• Materials Science
• Mechanical Engineering
• Corrosion Engineering

Background:

• Traditional fatigue life prediction methods are costly and data-intensive.
• Limited research exists on predicting metal fatigue in hydrogen environments using deformation inhomogeneity.
• Hydrogen embrittlement significantly impacts material performance.

Purpose of the Study:

• To investigate the influence of hydrogen pre-charging on the low-cycle fatigue (LCF) behavior of HRB400 steel.
• To develop a novel fatigue indicator parameter (FIP) for predicting LCF life in hydrogen environments.
• To establish the relationship between fatigue life and microscale deformation inhomogeneity.

Main Methods:

• Experimental fatigue testing of hot-rolled ribbed bar grade 400 (HRB400) steel.
• Crystal plasticity finite element method (CPFEM) simulations.
• Development of a new FIP incorporating hydrogen embrittlement index, axial strain variation coefficient, and macroscopic stress ratio.

Main Results:

• Hydrogen charging altered cyclic hysteresis and reduced LCF life.
• The novel FIP accurately predicted LCF life of hydrogen-charged HRB400 steel within a factor of two error.
• The FIP effectively accounts for hydrogen charging effects and stress impacts on microscale deformation.

Conclusions:

• Hydrogen pre-charging significantly degrades the LCF resistance of HRB400 steel.
• The developed CPFEM-based FIP offers a reliable method for predicting LCF life in hydrogen environments.
• This approach overcomes limitations of traditional fatigue prediction methods.