Study On Forming And Microstructure Changes Of 30CrMoA Thin Wall Cylinders

30CrMoA steel is a kind of high-strength low alloy steel widely used in pressure vessels.Using this steel instead of traditional materials to produce a variety of commonly used cylinders can significantly reduce its weight,in order to save materials,ease transportation difficulties and reduce transportation costs.The processing of cylinders is generally carried out by the extrusion-ironing-spinning closing process.During the processing the process parameters are important factors affecting the microstructure and performance of the cylinders.In order to investigate the feasibility of using 30CrMoA forming cylinders and to control the quality of the cylinders,the constitutive equations and microstructure evolution models of 30CrMoA were established through experiments,and the extrusion and ironing of 30CrMoA were performed using Deform-3D finite element analysis software.The deep drawing process and microstructure evolution were simulated.Using Gleeble-3800 thermal simulation tester,thermo-compression deformation test of 30CrMoA with deformation of 60%at a temperature ranges 1173-1373K and in the strain rate ranges of 0.01-10s^-1 was carried out under different deformation conditions.The deformation behavior was studied,and the constitutive equation of high temperature deformation of 30CrMoA and the dynamic recrystallization model based on Avrami dynamic recrystallization theory were established.Using Deform-3D finite element analysis software with constitutive equations and dynamic recrystallization equations,extrusion temperatures ranges 1273-1373K and extrusion speeds ranges of 7-150 mm/s were simulated for different deformation conditions.The grain size under different deformation conditions was for comparative analysis.The results show that at the deformation temperature of 1373K and the extrusion speed of 150mm/s,the average grain size of the extruded part is the smallest.The temperature ranges of 1193-1343K and the extrusion speed ranges of 50-150mm/s were used to simulate the ironing,and the grain size under different deformation conditions was compared and analyzed.The results show that the average grain size of ironing parts is the smallest when the deformation temperature is 1243K and the deformation speed is50mm/s.Using a self-designed experimental die,the extrusion experiment at the temperature of 1373K,the extrusion speed of 7 mm/s,and the ironing experiment at the temperature of1243K,the drawing speed of 7 mm/s was performed.The load-stroke curve of extrusion-ironing process was obtained,and metallurgical structure diagrams of various parts of the extruded parts and ironed drawn parts were obtained through metallographic experiments.The experimental results are basically consistent with the numerical simulation results under the same deformation conditions.It is verified that 30CrMoA high temperature deformation constitutive equation and the dynamic recrystallization model can be used to predict the microstructure evolution of the material and it is feasibility the material adopts extruding and ironing forming cylinder.