Study Of Heat Treatment Process Of A356 Aluminiun Alloy Automotive Wheel Hub

With the increasing energy crisis in the world,the demand for lightweight automobile has been increasing,and the application of aluminum alloy wheels,as the main target of automobile lightweighting,has been increasing in the automotive industry.At the same time,the wheel hub manufacturers have the new challenges to meet the demands of high-quality,low-cost requirements,wheel manufacturing enterprises need to improve production efficiency and ensure product quality.Therefore,the heat treatment process of the wheel hub should be improvement.In the present study,we chose A356 aluminium alloy automotive wheel hub to study the variation of microstructure and mechanical properties of the metals during different heat treatments with lots of methods such as optical microscopy,scanning electron microscope analysis,differential scanning calorimetry and mechanics performance testings.The relations between the solution treatment technology and the microstructure as well as the microhardness are investigated by variation of solution treatment parameter.The grain size of the eutectic silicon particles was reduced with increasing temperature in a certain range.The higher of the solution temperature and the longer of the heat preservation time are,the eutectic silicon particles have the trend of spheroidized and homogenization.But exorbitant temperature or over insulating will make the particles coarsening.Correspondingly,the value of the microhardness increased at first and then decreased with increasing the solution temperature and the heat preservation time.As a result,the A356 aluminum alloys have good comprehensive mechanical properties by solution treatment for 5 hours at 540?.In addition,fine and spheroidized particles uniformly distributed in the matrix,and the microhardness reached its maximum.The relations between the aging heat treatment technology and the mechanical properties are discussed by changing aging technology parameters.The strength and hardness increased but the plasticity decreased at higher temperatures being set.Thus,the A356 aluminum alloy have good comprehensive mechanical properties by aging heat treatment for 3 hours at 150?,when G.P ?zone,fine ?'-phase and ?-phase existed simultaneously,and the tensile strength is 267 MPa,the hardness is 121 HV,and the elongation is 18.5%.The fracture surface presented typical dimples with good plasticity at low aged temperature.