Study On Casting Process And Properties Of Large Size ZL205A Alloy Shell Components

ZL205A aluminum alloy is A kind of high-strength casting aluminum alloy developed by China in the 1970 s,and it is also a casting alloy with the highest tensile strength and better comprehensive mechanical properties in the world.Because the range of solidification temperature is relatively wide,the casting performance of the alloy is relatively poor,especially in the casting process of large components with high ratio of diameter to thickness.It is easy to produce casting defects such as segregation,shrink,thermal cracking and so on.In this paper,the purpose of a sound casting is achieved by the process optimization of the ?1300 shell casting,and the optimized process is applied to the casting ?1800 shell according to similar principles such as casting materials,process and product structure.The thin-walled cylinder-shaped casting uses a mold anti-gravity low-pressure gap pouring system with a low pressure of 0.6-08 Mpa for casting production.The modular combination method was designed for large-size complex meshed structural shell casting molds.The sand core mold of the shell of the ?1300 is designed with an internal melon-petal,external-to-open structure.The main structure of ?1800 shell is the core mold structure,i.e.the inner tube living block ribs,the frame-type ring band,the overall outer tire tight inner tube structure scheme.Number of cylinders: ?1300 shell includes 24 cylinders,retrenchment distance is 170mm;?1800 shell includes 32 cylinders,retrenchment distance is 177 mm.The gate width of the pouring system: ?1300 shell casting includes gap gate size 20/30mm;?1800 shell casting includes gap gate size 25/35 mm.The diameter of the cylinder: for ?1300 shell,the diameter of the casting stand-box is 65/60 mm,the casting stand-box of ?1800 shell is 80/70 mm.Cooling system: the main wall of the casting of the shell of 1300 solid thick cold sand cooling,the upper flange double-sided cold iron cooling,(the thickness of the corresponding wall thickness of 1 times,the thickness of the inner surface is 1.5 times the corresponding wall thickness);The main wall of the ?1800 shell thick cold sand cooling,the upper flange double-sided cold iron cooling(the thickness of the corresponding wall thickness is 1 times,the inner surface thickness is 1.5 times the corresponding wall thickness);The cooling of the single-sided cold iron under the flange is 2 times the thickness of the corresponding wall,and the thickness of the thickened zone is 2 to 2.5 times the thickness of the corresponding wall.Based on the above pouring system and cooling system window optimization design,the casting simulation analysis was completed using Pro CAST simulation technology.Casting ?1300 shell castings using pouring temperature of 715?,boost rate 0.8125 KPa/s,pressure 100 KPa scheme,casting internal do not have shrink holes,shrinkage,and segregation,a small number of shrink-holes,shrinkage,segregation defects are present in the vertical and pouring internal,casting internal quality reach the technical standard.The ?1800 shell castings are also simulated by Pro CAST simulation technology,without shrinkage porosity and cavity,shrinks,or segregation inside,and the internal quality of the castings reach standard.Through the above process scheme,the castings are tested and verified to meet the technical requirements of the product.