Study On Numerical Simulation Of Solidfication And Deformation Of Titanium Alloy Thin-walled Castings During Sand Casting

Titanium alloys are used in the field of aerospace due to its good mechanicalproperties. Titanium alloy thin-walled castings generate large deformation due to badmold concession during casting. In order to mitigate problem of deformation ofthin-walled castings, U.S.A develop a sand casting. Our country is short of availableexperience in titanium alloy sand casting. Titanium alloy thin-walled castings haveshrinkage porosity and deformation, which affects casting quality.seriously. This papermainly research the shrinkage porosity and deformation of thin-walled BT20titaniumalloy castings by numerical simulation method during sand-casting. It will be helpfulfor formulation of process parameters during practical production and to improvequality of castings.This paper mainly uses Pro/E software to build casting mold and design of runnersystem and simulates castings by ProCAST software, including vacuum law pressurecasting and centrifugal casting. The deformation of titanium alloy stress box arestudied at1790℃,1820℃and1850℃and at3:1,6:1of thickness ratio by numericalsimulation method during vacuum low pressure casting. We analyze mechanism ofdeformation of castings. According to simulation results, we summarize that thedisplacement and deformation of ratio smaller titanium alloy stress box becomes moreand more smaller from8mm to4mm, deformation ratio from4%to2.3%with pouringtemperature increasing; the displacement and deformation of larger ratio stress boxincreases firstly and then decreases, from9mm to10mm to7mm, deformation ratiofrom8%to9%to7.5%with pouring temperature increasing.According to simulation results, we get optimal parameters, centrifugal rate of200rpm and500℃of preheating molds, which have less effect on deformation ofcastings by orthogonal. The law of deformation and shrinkage porosity of BT20titanium alloy cylindrical work-pieces are got by simulating size of400×500mm，500×600mm and600×600mm and thickness of2mm，3mm and4mm BT20titanium alloy castings during centrifugal casting.The deformation of BT20titanium alloy cylindrical work-pieces becomes moreand more larger, deformation ratio from20%to75%, with wall decreasing and sizeincreasing. Shrinkage porosity ratio is from1.2%to0.9%to1.0%at the same size ofcastings. Both the displacement and deformation of ends of castings is larger and that of bottom is larger3-4mm than that of top. Plastic strain is generated near runner, withmaximum ratio of40%. Deformation ratio of thin-walled area is small and1-2%due tosolidification at the same time.