| Cu-Cr-Zr alloy with high strength and high conductivity is one of the typical precipitation hardening alloys. As the most promising functional material, Cu-Cr-Zr alloy has excellent comprehensive properties and mechanical properties. It has been widely used in many fields like machinery, national defense and electronic. Under high temperature and alternating stress, fracture that caused by fatigue and creep damage is the main factor leading to the final material failure. Therefore, Cu-Cr-Zr alloy requires good resistance to high temperature damage performance. This paper has investigated the high-temperature tensile, fatigue and fatigue-creep behavior of solid-solution aging and rolling aging Cu-Cr-Zr alloy with Instron8801 tensile fatigue testing machine, OM, SEM, TEM and other analysis and observation methods. In this paper, the main research contents and final results are as follows:After studied the high-temperature tensile behavior of two states Cu-Cr-Zr alloys at 200?-600?, we found that on the same temperature, rolling aging Cu-Cr-Zr alloy shows higher tensile strength, while solid-solution aging alloy shows better elongation. The alloys under two different treatments at room temperature to 300? showed good plasticity and strength. The tensile strength of solid-solution aging alloy is 308.6MPa, the elongation is 18.1%, reduced by 13.5% and 8% compared with room temperature. And the tensile strength of rolling ageing alloy is 389.5MPa, the elongation is only 13.2%, reduced by 24% and 0.7% compared with room temperature. They both can meet the requirements of industrial applications. With the increase of temperature, the tensile property becomes different. At 600?, the tensile strength of aging state alloy is 43% lower than 300?,the elongation increased by 35%. But rolling ageing alloy is reduced by 19% and 40% respectively.After studying fatigue performance of Cu-Cr-Zr alloys under two different treatments through the different combination of temperature and stress amplitude, we figure out the influence of temperature and stress amplitude to fatigue behavior. It can be found that as the stress amplitude rises, week fatigue fracture under different test temperature alloys are in decline. But with the increase of test temperature, fatigue limits of the alloys under two different treatments are different. The fatigue limits of alloys in different states at room temperature are close to 300 MPa. At 300?, the fatigue limit of solid-solution aging Cu-Cr-Zr alloy is 230 MPa, then decrease to 210 MPa at 400?. But the fatigue limit of rolling aging Cu-Cr-Zr alloy get a larger increase to 330 MPa at 300?, then decrease to 300 MPa at 400?. Rolling aging Cu-Cr-Zr alloy at high temperature showed more excellent fatigue resistance.After studying fatigue-creep performance of Cu-Cr-Zr alloys under two different treatments in 300?, the influence of temperature, maximum stress, the holding time and average stress on the S-N curve is found. It can be found that fatigue-creep interaction occurs mainly under the conditions that the stress amplitude is slightly less than the average stress, led to the failure of materials. In creep zone, when the average stress is much higher than stress amplitude, creep damage occupies a large proportion, while the influence of fatigue factors can be ignored. At the beginning solid-solution aging Cu-Cr-Zr alloy is cyclic hardening, and show cyclic softening in the late. The greater the load level, the higher the temperature, cyclic softening trend is more obvious. Rolling aging Cu-Cr-Zr alloy only shows cyclic softening under the condition of high temperature and high stress in the late. Observing the fracture morphology of the alloys after fatigue-creep interaction can find both fatigue and creep fracture characteristics, the nucleation of crack is on the surface of the specimen, the dimple and the loose part. The early crack extension is given priority to fatigue factors, the late crack propagation is given priority to creep factors. |
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