Research Of Magnesium Alloy Liquid Forging Process

The forming process of the Magnesium Alloy Liquid Forging is a new semi-solid formingmethod of the new-type metallic material, and its craft process is poured the liquidmagnesium alloy directly into a preheated mold cavity, through the mould punch’s press, thealloy liquid plastic flow under the high mechanical stress and crystallization,when the metal isin a state of half melting or solidification. This technique combines the advantages of liquidmolding and solid molding, and can obtain higher quality of liquid forging.The quality offorge piece mainly depends on the molding parameters, this article focuses on the three mostimportant process parameters that effect on the magnesium alloy liquid forging, includes theliquid forging pressure, the pouring temperature of molten alloy and the preheat temperatureof liquid composition. It is concluded that the best process parameters combination fromstudying the parameters effect on the quality of the liquid forging by orthogonal experimentalscheme.The material, this experiment chooses, is the magnesium alloy of AZ31, and theexperiment equipments are the special holding furnace and the general hydraulic press. Wecan get the magnesium alloy tensile samples use the liquid forging technology. In the processof designing experiment scheme, combining with the experimental conditions and experimentpurpose, analyses and choose the liquid forging parameters, and make the specific instructionsto the operation of the test process. Magnesium alloy liquid forging parameters are as follow:(1) The liquid forging pressure of40MPa to80MPa, the gradient is10MPa;(2) The pouring temperature of molten alloy is650℃~730℃, the gradient is20℃;(3) The mold preheated temperature is150℃~350℃,the gradient is50℃;(4) Pressure time is3s;(5) The holding time is15s.The parameters have an effect on the performance of liquid forging, and we can getdifferent alloy from changing the process parameters. By the performance test of the liquidforging under different process conditions, we get the following results:(1) Compared with the ordinary casting, the performance of the liquid forging increasedgreatly; (2) The increase of liquid forging pressure makes the density of liquid forging andhardness increase;(3) With the increase of the liquid forging pressure, the pouring temperature and themold preheating temperature, the tensile strength of specimens is high rise before fall, and thepeak is near a particular parameter value;(4) The microstructure of sample density and the grain refinement are influenced byliquid forging parameters, the different conditions of the tensile fracture show the diversecharacteristics of morphology.By observing the experimental phenomena and studying the experimental results, we canfind out the liquid forging quality by the influence of parameters and deal with the resultsused the Matlab software. Comprehensive analysis, the main conclusions that the bestmolding parameters of liquid forging for the magnesium alloys are as follow:(1) The liquid forging pressure is70MPa to75MPa;(2) The pouring temperature of liquid alloy is680℃~690℃;(3) The preheating temperature of the liquid is about250℃.