Simulation Study On Hydrostatic Extrusion Process Of Bimetal Composite Bar Based Pressure Loading Model

The bimetallic cladding material is a kind of composite material which is composed of two kinds of metal with different properties.It has the advantages of two kinds of component metals,which makes up for their shortcomings and has excellent comprehensive properties.In recent years,it has been more and more applied.Hydrostatic extrusion is a special extrusion process where the material is subject to the high hydrostatic pressure to be deformed under a liquid(pressure media)environment.The plastic forming ability of the material can be improved by using the hydrostatic extrusion technology to process the bimetallic cladding material and the plastic forming ability of the material can be improved.At the same time,it also improves the uniformity and interfacial bonding ability of bimetallic cladding materials,which is one of the effective means of processing deformation of bimetallic cladding materials.Because the experimental process of hydrostatic extrusion is tedious,the safety factor is low,the manufacturing process of hydrostatic extrusion die is long and the cost is high,the numerical simulation technology is used in the bimetallic hydrostatic extrusion process in order to save the experimental time.The purpose of this paper is to systematically study the force and flow law of bimetallic composite bar during hydrostatic extrusion through finite element simulation,analyze the influence of material and process parameters during the experiment and optimize the geometric shape of billet.So as to provide guidance for the practical experiment of bimetallic hydrostatic extrusion.This paper is based on a hydrostatic extrusion finite element model(pressure loading model)with hydrostatic pressure load.The hydrostatic extrusion process of bimetallic combinations with different flow stress ratios(Φ:0.167-1.667),different die angles(2α: 20 °,40 °,60 ° and 80 °)and different extrusion ratios(R = 1.56,2.25 and3.5)was simulated.Based on the conclusion of the extrusion pressure and flow difference under different process parameters,the flow behavior and stress and strain distribution of bimetallic materials are analyzed,aiming at the low probability of extrusion material fracture and the uniform flow of bimetallic.The forming rule of bimetallic hydrostatic extrusion process was summarized.Secondly,the effects of cladding forms(with or without top sleeve and bottom sleeve),bottom sleeve thickness(2.5mm-10mm)and section ratios(1/15、1/6、1/3、1/2)on the process of bimetal hydrostatic extrusion are studied in this paper.The importance of top sleeve and bottom sleeve during extrusion is verified,and the relationship between extrusion pressure and stress-strain distribution with the bottom thickness and section ratios is summarized.