Experimental Study On High Temperature Plastic Deformation Behavior And Hot Working Characteristics Of Copper Alloy (CuSn8P)

Tin bronze alloys are widely used in the fields of machinery manufacturing and defense industry due to their mechanical properties and process performance,especially for important wear-resistant and corrosion-resistant parts in engines,such as bushings and bearings.As the engine develops toward high speed,high explosion pressure,and high power,higher requirements are imposed on important components such as bearings and connecting rod bushings.Our group proposed that the thermal processing technology can change the material microstructure to achieve the performance of the lining and other components.Consequently,studying the hot deformation behavior and hot working characteristics of copper alloys and optimizing the forming process can effectively improve the strength,reliability,wear and corrosion resistance of the connecting rod bushings and other components,and prolong its service life,which is of great significance and practical value for engineering applications.In this paper,the CuSn8P alloy was used as the research object,and the single factor thermal compression simulation test was carried out on the Gleeble-3500 thermal simulation test machine.The thermoplastic deformation behavior of the alloy in the range of 200°C⁵00°C and strain rate 0.005 s^-15 s^-1 was studied.Firstly,the experimental data was processed by Origin software to obtain the flow stress curves of the alloy at different strain rates and deformation temperatures.The effects of strain rate,deformation temperature and strain on the flow stress are analyzed.Secondly,based on the hyperbolic sinusoidal constitutive equation in the Arrhenius model,the constitutive model of the high temperature rheological behavior of copper alloy CuSn8P is established.The model can accurately describe the high temperature rheological behavior of copper alloy CuSn8P.Thirdly,based on the DMM material dynamic model theory,the power dissipation diagram of the alloy CuSn8P under different strains is constructed.Based on the Prasad instability criterion,the rheological instability diagram of the alloy CuSn8P under different strains is constructed.The thermal processing diagram of the alloy is constructed by superimposing the two.Then analyze the thermal processing map to determine the safety zone and rheological instability zone of the alloy material during thermal deformation and the optimal process parameter range during hot working.Finally,the microstructure of the sample was characterized by scanning electron microscopy.The plastic deformation mechanism and microstructure change of the alloy during the deformation process were analyzed.The main conclusions are as follows:as the deformation temperature increases and the strain rate decreases,the flow stress of the alloy gradually decreases.The alloy is a heat sensitive,positive strain rate sensitive alloy.Under the same strain condition,the energy dissipation efficiency increases with the increase of temperature and decreases with the increase of strain rate.The peak energy dissipation efficiency of the alloy under different strains appears in the low strain rate region.And as the strain increases,the peak of energy dissipation efficiency increases gradually.When the alloy CuSn8P is hot-processed,the optimum process parameters are:temperature range 350°C⁵00°C,strain rate range 0.005s^-10.05s^-1.