Research On Squeeze Casting Technology Based On Motor Spring Seat Of A356.2 Aluminium Alloy

Automotive lightweighting refers to reduce its weight under the promise of comprehensive performance.It can achieve the purpose of weight loss,consumption reduction,environmental protection and safety.According to the statistics,if vehicle weight is reduced by 10%,fuel efficiency can be increased by 6%~8%.Lightweight also contribute to handling stability and security.Spring seat is supporting part which is used to install the spring on the automobile rear axle,usually is Q235 machined by stamping process.This study select A356.2 alloy instead of Q235,and apply the squeeze casting process.The request of mechanical properties is that yield strength meet the 220 MPa, the elongation meet 4%.In the process of research and development of the aluminum alloy spring seat,the study conduct comprehensive and in-depth research of squeeze casting technology.The experiment apply the ube HVSC350 PL squeeze casting machine to produce spring seat,the influence of foundry pressure,filling velocity and T6 heat treatment on microstructure and mechanical properties are studied,and analyze the filling and solidification situation combining Anycasting computer simulation technology.In the process of research, experimental conditions are quantified to ensure the repeatability of the experiment,such as tracking material composition,detecting slag content and hydrogen content to quantify melting quality.The plan for T6 heat treatment is 545?x6h+70?water quenching+180?+4h,comduct experiment of temperature uniformity of the furance,and adopt hierarchical warming heat treatment to ensure the scheme can be performed accurately.Conducting the stretch experiment,refering to the computer simulation results and the analysis of SEM,EDS,study fracture cause and the scheme of further improvement of the mechanical properties is given.In addition,modification effects of Sr-B,hole defects,bubble of heat treatment,Si segregation were studied.Research shows that the pressure increases solidification temperature gradient and promote the undercooling in pressure,improve nuclear driving force and decrease line growth speed.in the microstructure,size of a-Al phase significantly reduced compared with gravity casting, and with the increase of foundry pressure,the grain size decreases,the nonuniformity increases,ppearance also has the development trend of the crumb.With the increase of foundry pressure,the mechanical properties have a relatively small increase trend,but don't recommend improve mechanical properties through increase pressure within a certain range of foundary pressure.With the increase of the filling speed,the mechanical properties are improved obviously in state of as-cast and T6.High filling speed produced eddy current, but the strong convection and the scour of cavity wall prompted "free grain".In a certain speed range,mechanical properties can be improved by increasing filling speed.