Effect of microstructure evolution on high cycle fatigue behavior of brass

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 732; pp. 326 - 332
• Main Authors: Liu, Lin, Chi, Rui, Wang, Jiaojiao
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 08.08.2018; Elsevier BV
• Subjects: Brass; Crack initiation; Crack propagation; Cyclic loads; Deformation mechanisms; Dimpling; Dislocation structures; Dislocations; Evolution; Fatigue cracking; Fatigue cracks; Fatigue failure; Fatigue tests; Fracture mechanics; Grains; HCF; High cycle fatigue; Materials fatigue; Microcracks; Microstructure; Microstructure evolution; Morphology; Plastic deformation; Stress concentration; Dislocation structures; HCF; Brass; Microstructure evolution
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2018.07.016

The fatigue behavior and the microstructure of brass induced by HCF test are investigated systematically. The fatigue fracture morphologies are characterized by SEM. The microstructures are analyzed by OM and TEM. It is found that crack initiation of brass is accompanied by micro-cracks. In crack propagation region and final fracture region, secondary cracks and the dimples can be observed, respectively. The number of the twins increases, which can be attributed to the plastic deformation when brass subjects to HCF test. A series of change in dislocation structures refines the original grains into sub grains by forming new boundaries in the original grains. In addition, uneven microstructure distribution in the process of cyclic loading causes stress concentration, which generates the PSBs turned into preferential cracking initiation. The high cycle fatigue fracture mechanism of brass induced by dislocation structure evolution is proposed finally. •PSBs become the priority sites of crack initiation.•Original grains refine to sub grains induced by dislocation movements.•A fatigue fracture mechanism of brass during HCF is proposed.