Finite Element Numerical Simulation Of Hot Indirect Extrusion Process Of 6061 Aluminum Alloys

In the dissertation,the deformation behaviors of aluminium alloys for 6061 during high speed extrusion process at a lower temperature have been extensively researched by physical and numerical techniques.Such as THERMORESTOR-W hot simulator,finite element software ABAQUS and so on.The results are as follows:l.From hot simulator,The results show that the flow stress gets smaller with the increase of deformation temperature at the same strain rate,and becomes larger with the increase of strain rate at the same temperature.The true stress-strain curves exhibit oscillations apparently and the formation of new grains during hot deformation has been found out.Dynamic recrystallization can have taken place,though there is the high stacking fault energy for aluminum alloys.2.The flow stress of 6061 aluminum alloy during hot-compression can be described by Zener-Hollomon parameter under the laboratory conditions, and the deformation activation energy is 236.858 kJ/mol and stress exponent n is 8.926.The Zener-Hollomon parameter,Z,is defined by the expression:Z =εexp(236858/RT),εin it isε=1.46×l0¹⁹[sinh(ασ)]^8.926exp(-236858/RT).3.The 6061 aluminium 's macrostructure shows:At the same teperature point,the grain size is reducing as the strain rate increase;The grain size reduces is increasing as the temperature increase,when the strain rate is a constant,and the temperature influence on grain size is becoming more and more obviously when the strain rate is lower.4.The hot extrusion process of aluminum alloys 6061 at extrusion temperatures and extrusion speed was numerically simulated by FEM.The results show that the calculated values of load and temperature near the discharge port are close to the measured ones under factory condition.Then all temperature and speed combinations were simulated by finite element software of ABAQUS.The results that under extrusion speed 15mm/s,extrusion temperature 350℃,which is a appropriate one.