Acta Metallurgica Sinica (English Letters) ›› 2019, Vol. 32 ›› Issue (12): 1521-1529.DOI: 10.1007/s40195-019-00965-5

• Orginal Article • Previous Articles     Next Articles

Torsional Fatigue Cracking and Fracture Behaviors of Cold-Drawn Copper: Effects of Microstructure and Axial Stress

Rong-Hua Li1(), Peng Zhang2(), Zhe-Feng Zhang2   

  1. 1 School of Mechanical Engineering, Liaoning Shihua University, Fushun 113001, China
    2 Laboratory of Fatigue and Fracture for Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
  • Received:2019-07-03 Revised:2019-09-10 Online:2019-12-10 Published:2019-11-25

Abstract:

The fatigue cracking and fracture behavior of cold-drawn copper subjected to cyclic torsional loading were investigated in this study. It was found that with increasing stress amplitude, the fracture mode of cold-drawn copper gradually changes from a shear fracture on transverse maximum shear stress plane to a mixed shear mode on both transverse and longitudinal shear planes and finally turns to the shear fracture on multiple longitudinal shear planes. Combining the cracking morphology and the relationship between torsional fatigue cracking and the grain boundaries, the fracture mechanism of cold-drawn copper under cyclic torsional loading was analyzed and proposed by considering the effects of the microstructure and axial stress caused by torsion. Because of the promotion of the grain boundary distribution on longitudinal crack propagation and the inhibition of axial stress on transverse crack grown, the tendency of crack propagation along the longitudinal direction increases with increasing stress levels.

Key words: Torsion, Fatigue behavior, Crack propagation, Fracture mechanisms, Axial stress, Copper