Fatigue Modeling Containing Hardening Particles and Grain Orientation for Aluminum Alloy FSW Joints

• Published in: Materials Vol. 12; no. 12; p. 2024
• Main Authors: Sun, Guoqin, Guo, Yicheng, Han, Xiuquan, Shang, Deguang, Chen, Shujun
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 24-06-2019; MDPI
• Subjects: Aircraft industry; Alloys; Aluminum alloys; Aluminum base alloys; Computer simulation; Crack initiation; Crack propagation; crystal plasticity theory; Crystal structure; Ductility; friction stir welded joint; Friction stir welding; Grain boundaries; Grain orientation; Grain size; Hardening; Heat affected zone; Kinematics; Macroscopic models; Material properties; Materials fatigue; Mechanical properties; Metal fatigue; Metallurgy; Microstructure; Misalignment; Morphology; Propagation; Simulation; Single crystals; Strain; Strain hardening; strengthening particles; stress and strain responses; Stress concentration; Stress transfer; Tension tests; Beijing China; United States > US; China; Japan; strengthening particles; stress and strain responses; crystal plasticity theory; friction stir welded joint
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma12122024

The macro-mesoscopic joint fatigue model containing hardening particles and crystal characteristics is established to study the effect of the hardening particles and the grain orientation on fatigue properties of an aluminum alloy friction stir welding (FSW) joint. The macroscopic model is composed of the weld nugget zone, thermo-mechanically affected zone, heat-affected zone, and base material, according to the metallurgical morphology and hardness distribution of the joint. Cyclic stress and strain data are used to determine the material properties. The fatigue parameters used in the calculation of cyclic stresses and strains are obtained with the four-point correlation method. The mesoscopic models of different zones are inserted into the joint macroscopic model as submodules. The models containing the information of hardening particles and grain orientation are established with crystal plasticity theory for the grains and isotropic hardening rule for the hardening particles. The effects of hardening particles and grain orientation on the stress and strain responses are discussed. The simulation results show that high-angle misorientation of adjacent grains hinders the stress transfer. The particle cluster or cracked particles intensify the stress and strain concentrations.