Research Of Handling A356Semi-soild By Double Sound Field Power Ultrasonic And The Process Of Rheological Forming

Semi-solid metal forming technology combines with the advantages of the liquidmetal forming and the solid state metal forming, the formed part can eliminate theforming defects in a single state, and energy consumption is very low, therefore itbecomes the hot spot in the study of scientific research workers and has wideapplication prospect. The key of semi-solid forming technology is to prepare the slurry(small and round grain organization), while preparing the semi-solid metal slurry bypower ultrasonic is a kind of environmental process.This subject will take the handled semi-solid metal slurry by power ultrasonic topour into the preheated mold cavity and form through the hydraulic press, namely therheological die forging. This subject chooses A356material, because it has a widesemi-solid temperature range, can make the formed part have better performance.In order to the rheological die forging experiment, I design a set of the temperaturecontrolled power ultrasonic device and a pair of mold on rheological die forging. Thissubject experiment is divided into two stages, The first stage handles different pouringtemperature (625℃,615℃,605℃) A356melt by power ultrasonic, to find the bestpouring temperature to prepare for the second stage experiment; The second stageexperiment takes the A356melt by power ultrasonic on rheological die forging, thenfinds out the best process parameters and the influence law through contrasting andanalysing of the formed parts’ organization and performance under different formingpressure (110MPa,125MPa,140MPa) and the holding time (10S,15S,20S).The experimental results show that:(1) The grains of A356melt by powerultrasonic become smaller and rounder, and the best effect is the pouring temperature at615℃, its average grain size is43.5μm, average shape factor is0.84;(2) In therheological die forging process, the influencing process parameters on A356organization: pouring temperature> forming pressure> holding time, the pouringtemperature mainly affects the grain size and compactness, the forming pressure mainlyaffects roundness, and the best process parameters are (615℃,125MPa,15S), itsaverage grain size, average shape factor, compactness respectively is:32.6μm,0.86,88.9%;(3) Comparing the performance of the A356formed parts with rheological dieforging after power ultrasonic and direct rheological die forging, the tensile strength (about205MPa) and elongation (about8.50%) improve obviously;(4) The formedparts’ tensile strength and elongation have different degrees of improvement through atreatment called T6, the efficient of material can get a great improvement, and finds thatthe tensile strength achieves maximum241.20MPa when the pouring temperature is615℃, and the elongation improves with temperature reduction in the pouringtemperature range, the highest is17.88%at605℃, which provides the basis forselecting process parameters in practical application.The subject combines the new slurry-making process with the rheological forming,develops a new semi-solid forming technology, not only has the innovation in thetechnology,but also has certain reference on inspiring people’s thinking and broadeningthe horizon.