Microstructures And Mechanical Properties Of Cu-Sn Alloy Subjected To Hot Compression And Power Spinning

Cu-Sn alloys have excellent wear resistance,corrosion resistance and comprehensive mechanical properties.It is commonly used in bearing,turbine,bushing and other parts.Taking the diesel bushing as the research object,we need hot deformation for the copper tin alloy bar in the early process of bushing.First,we need to confirm the optimum parameters of temperature and strain rate through the hot compression test under laboratory conditions.The tin bronze QSn7-0.2 as the research object,using the Gleeble.3800 thermal/mechanical simulator,DM4000 optical microscope,Nova scanning electron microscope NanoSEM430,CMT5105 type high temperature tensile test machine,AL.Y3700 type XRD instrument research on Microstructure and mechanical properties,the main research contents and results are as follows:First of all,the Bush is made of copper tin alloy bar of hot compression test,the hot compression stress.strain curve analysis of the softening law of work hardening and recrystallization,established the constitutive equation of general properties,and draw the hot processing map,combined with high energy dissipation rate region.The optimal process parameters are derived.The dynamic recrystallization law and the change of mechanical properties in the process of high temperature compression were analyzed by EBSD and mechanical properties test.On the test machine for isothermal compression tests of Cu-Sn alloy in Gleeble.3800D thermal simulation,thermal compression strain rate of 0.001s.~1~10s.~1,the thermal deformation temperature of 500?~700?,the hot processing map of high temperature alloy compression,deformation mechanism research.The flow stress decreases with increasing deformation temperature,and increases with the increase of strain rate;hot deformation flow stress in the process by the hyperbolic sine constitutive equation to describe the rheological stress.at the same time using the stepwise regression.According to the dynamic material model,calculation and analysis of the hot processing map of alloy,Through EBSD,discovery and detection of mechanical properties,thermal compression process is based on the dynamic recrystallization is dominant,plastic deformation mechanism coordination mechanism and the occurrence of mixed twins,of which Cu-Sn alloy during high temperature deformation and grain boundary misorientation and to continue to produce more high angle grain boundary gradually tends to be a dynamic balance.The CSL grain boundary reacts with the ordinary grain boundary to produce the large angle grain boundary of the?3.Under different hot compression temperatures,the grain boundary distribution of CSL has changed a lot,which affects the mechanical properties of materials,and leads to the migration and sliding of grain boundaries.The mechanical properties are stable and the plasticity slowly descends at different thermal compression temperatures.The internal stress of the material decreases with the increase of the thermal shrinkage temperature.By TEM,EBSD to Cu-Sn alloy spinning group before and after annealing organization analysis,research shows that:after the power spinning alpha refinement,evolved into the small deformation of alpha and alpha grain,the average grain size is about 2.2?m because of strain hardening,spinning after the most in a large number of the grain boundary in the slip line in distribution network,the grain structure and dislocation distribution in the community After annealing,emerged in 400?when more dislocation cell and dislocations,recrystallization crystal grain crystallization started sliding,twin crystal growth rate,growth way is mainly caused by fault of continuous accumulation At the time of 500?,there were less defects of equiaxial grains,and the twin crystals grew with the fault of the laminates.The results showed that the strong spinning effect was obvious and had good mechanical properties.