Study On Microstructure Evolution Of Cu-Sn Alloy Cylindrical Parts During Hot Spinning Forming

Because of its good bearing characteristics,copper-tin alloy cylindrical parts are widely used as connecting rod bushings for heavy-duty diesel engines at home and abroad.Due to the complex service environment,higher requirements are put forward for its performance im-provement and cost reduction.Hot spinning,as an advanced forming process for rotating parts,has become one of the best ways to prepare cylinder parts with excellent properties.Currently,hot-spinning research of cylindrical Cu-Sn alloy parts is primarily focused onthe forming pro-cess,dimensional precision and form-defect control of parts,but there is a paucity of research on the microstructure evolution of cylindrical parts during spinning.For this reason,this paper takes the QSn7-0.2cylindrical parts of Cu-Sn alloy as the object of investigation,and uses the method of combining experiment and finite element simulation to investigate the hot defor-mation behaviour of the alloy Cu-Sn and the law of microstructure evolution in the hot spinning forming process under different technological conditions,which provides an important bench-mark for hot spinning process technology.The main content of the research is:（1）The hot compression test of QSn7-0.2 was carried out on the Gleeble 3800 thermal simulation tester,and the true stress-true strain curve obtained by the experiment was deeply explored.The hot deformation behavior and microstructure deformation mechanism of Cu-tin alloy were obtained,and the dynamic recrystallization kinematics and dynamics model and the dynamic recrystallization grain size model were established.（2）By using Fortran language,the kinematics and dynamics models of dynamic recrys-tallization and the dimensional models of dynamic recrystallization of Cu-Sn alloy were im-ported into DEFORM-3D subroutine,and the hot spinning simulation system of Cu-Sn alloy was established for simulation.The axial and circumferential microstructure evolutions of dy-namic recrystallization grain size,dynamic recrystallization volume fraction and average grain size during hot spinning were obtained.The results show that the volume fractionX_drex of dynamic recrystallization increases obviously with the increase of temperature and two spin-ning cycles,and the average grain size d decreases,while the gap betweenX_drex and d inside and outside the cylindrical parts Narrows gradually.（3）according to the existing experimental conditions,the multi-pass hot spinning experi-ments of Cu-tin alloy with different temperature and thinning rate were carried out,and the metallographic microstructure and grain microstructure of the spinning parts were observed.Comparing the simulation results under the same conditions,it is found that the results are basically consistent,which verifies the validity of the dynamic recrystallization model and nu-merical simulation.