Study On Low Cycle Fatigue Properties Of Copper Alloy Contact Wire

This paper uses metallographic method analyze the softening temperature and re-crystallization temperature range of Cu-Mg alloy contact wire, study softening resistance performance by hardness test, Finally, study on low cycle fatigue properties of Cu-Mg alloy contact wire and through aging method to simulate Cu-Mg alloy contact wire in the actual operating environment after using 5 and 10 years, and study its low-cycle fatigue properties. The study found:cross section of Cu-Mg alloy contact wire, the grain is very small, showing the multilateral shape, but the side section, grains are obviously elongated, showing long strip fiber, drawing deformation of cold causes Cu-Mg alloy produced a strong plastic deformation and resulting in strain hardening. The re-crystallization temperature range between 300-450℃, softening temperature is about 365℃of Cu-Mg Alloy.The low-cycle fatigue experiments of Cu-Mg alloy contact wire was done under steady-state cycle, The transition life NT of Cu-Mg alloy without aging between the plastic strain amplitude 0.1 to 0.15%. Cyclic strain hardening exponent n'=0.1556, cyclic Strengthen coefficient K'=532 MPa, the fatigue strength exponent b=-0.0675, fatigue strength coefficient a'=251 MPa, the fatigue ductility exponent c=-0.5852, fatigue ductility coefficientεf'= 0.2169, and has good fatigue performance. Cu-Mg alloy without aging, increases with the number of cycles then occurs the phenomenon of cyclic softening under the control of the strain amplitude, when the cracks occurs, the inflection point of hysteresis loop showed in the cyclic stress-strain curves. Cu-Mg alloy after aging when 0.1%strain amplitude control, remained cyclic softening phenomenon, and the trend is similar to not aging, at 0.2%and 0.35%strain amplitudes, cyclic softening after first cyclic hardening and fatigue life compared with non prescription obviously decreased. Cu-Mg alloy's low-cycle fatigue fracture is a typical macro-morphology of fatigue fracture in tension and compression. Instant-off area has a large number of dimples under 0.1%strain amplitude, with good toughness. Instant-off area is tear fracture under the strain amplitude of 0.2%and 0.35%, after aging transient-off region has a large number of dimples under 0.2%strain amplitude, under 0.35%train amplitude transient-off region only has a small of dimple distribution.