Research On Precision Investment Casting Technique For K4169under Support Abutment

Superalloy with high temperature strength, good oxidation resistance and remarkable overall performance is an indispensible materical in the fields of aviation, aerospace and energy. The investment casting is a suitable technology for the superalloys with high alloying and hard hot working. In general, the superalloy castings with great size and considerably vary thickness are under development, so research for solving questions on controlling the size and shrinkage porosity during the investment casting. This paper studies the investment casting technology for the under support abutment, and produces qualfied superalloy casting.The under support abutment, which is composed of an upper flange, a lower flange and a rampart on which there is irregularly distributed of some bosses, is one of the key component of a liquid oxygen-hydrogen engine. It is very difficult to cast because of the considerably vary thickness. The under support abutment with requirement of high dimensional accuracy and metallurgical quality is casted in K4169by precision-investment casting. This paper optimizes the technology including the wax preparation, pouring and heat treatment by the combination of the simulation and experimental study, and it produces the casting for the working requirement.The results show that the block mold is prepared by post forming conforms to the technical provision and this technology increases the dimensional accuracy and surface finish quality effectively. The numerical simulation is used to acquire the optimized pouring system and casting parameters by the simulating of the filling and solidifying process, the casting using the united pouring system, the feeding system with connecting of the flow gate and the thinner flange, and the casting parameter of mold temperature900℃and pouring temperature1420℃, can get good metallurgical qualities and high ratio of finished products.The effect of different heat treatments on microstructure and properties is studied and the results indicate that hot isostatic pressing treatment can abate the porosity, pore and segregation of the K4169alloy, the improved heat treatment,1095℃×2h/AC+955℃×2h,117℃/h to605℃/AC+720℃×8h,50℃/h to650℃×8h/AC, can makes the microscopic structure homogeneous, and controls the precipitation and growing of the y" phase, so the cast has an excellent combination property and can satisfies the working requirement.