Preparation Of High Performance Cu-sn Alloys With Hot Forged State And Research Of Their Power Spinning Process

In order to study the hot deformation behavior and hot working properties of QSn7-0.2tin bronze alloy,seek for reasonable hot processing technology of tin bronze alloy,prepare hot forged alloy materials with excellent comprehensive properties,the hot compression experiment of QSn7-0.2 tin bronze alloy was carried out by using Gleeble-3500 thermal simulator.The mechanical properties,microstructure evolution and deformation softening mechanism of tin bronze at high temperature were studied by means of metallographic structure observation.Arrhenius phenomenological constitutive equation was established to characterize the relationship between temperature,strain rate,deformation and flow stress during hot deformation of tin bronze.According to the dynamic materials model,the hot working diagram of tin bronze was established,and the hot deformation characteristics of the alloy were analyzed.Based on the hot working diagram,the optimum processing parameters of tin-bronze alloy were determined,and the hot forged tin bronze alloy was prepared by hot extrusion.In order to further improve the strength and hardness of tin bronze alloy,the hot forged tin bronze was formed by power spinning based on the design test of response surface method,and the effects of different spinning process parameters and post spin heat treatment temperature on the hardness of the forming part were studied.As well as the interaction between different process parameters,the regression prediction model of correlation hardness response and process parameters was established,and the process parameters were optimized.The main conclusions of the study are as follows:?1?during the hot deformation of tin bronze alloy,the flow stress increases rapidly and then tends to stabilize,the rheological curve shows the characteristics of steady-state rheology as a whole.In the case of same other experimental conditions,the flow stress decreases with the increase of deformation temperature and increases with the increase of strain rate.Under the experimental conditions,the activation energy Q of hot deformation is 180.9 kJ/mol.The established constitutive equation of high temperature plastic deformation of the alloy has been verified,and the error is kept within 10%compared with the measured value,which can accurately describe the relationship between flow stress and deformation parameters.?2?In the heat processing diagram,the peak power dissipation efficiency is mainly concentrated in the strain rate range of 0.01⁰.032 s^-1.The distribution region of peak power dissipation efficiency moves to the right with the increase of deformation temperature.With the increase of the strain,the peak power dissipation efficiency decreases and the range of variation decreases.With the increase of strain,the region of rheological instability moves in the direction of increasing strain rate.Combined with the strain variables of the actual production,the optimum technological parameters for the hot working of tin bronze alloy can be selected:the deformation temperature is 680⁷30? and the deformation rate is 0.01⁰.032s^-1.?3?When the hot deformation temperature is 720? and the deformation rate is0.032s^-1,it is found that the original coarse grains have fully dynamic recrystallization,and even fine equiaxed crystals have been formed,and there are lots of twins in the hot extrusion forming of tin bronze alloy.The strength,hardness and elongation of the alloy have been improved to some extent.?4?The hardness of the material increases with the increase of thinning rate and feed ratio,and decreases with the increase of heat treatment temperature.The effect of the thinning ratio?A?and feed ratio?C?on the hardness of the material was highly significant,the heat treatment temperature?B?,the coupling of AC and the coupling of BC at the heat treatment temperature was significant.The ternary quadratic prediction model based on Brinell hardness,thinning rate,heat treatment temperature and feed ratio as independent variables has been verified to have high accuracy.The optimized process parameters are as follows:the thinning rate is 34%,the feed ratio is 0.5 mm/r,and the heat treatment temperature is 300?.