Nickel Base Alloy Vacuum Furnace Smelting Process And Product Performance Analysis

At present, nickel base superalloys with Wide usagcexcellent performance, higher and higher alloying degree and containing oxidizable elements at home and abroad use duplex process even triple process melting to purify the liquid metal. But some casting enterprises of no having the vacuum equipment need to develop or small batch production of nickel based high temperature alloy, so exploration using what process and what measures to take smelting, casting performance qualilled nickel base superalloy castings has important significance in non vacuum environment.In this paper, according to the structure of heat back cavity and a piston cavity, nickel base alloy properties and characteristics of Investment casting and conditions of non vacuum smelting.1specifically design for the bottom gating system of the casting and carry on the anahsis by using computer simulation.In order to avoid ceramic core floating defect and providing similar vacuum environment of melting and casting, i design the surface of long ceramic core with screw thread and special gas protection device. On the basis of the stainless steel production experience and optimizing the casting process parameters with the technology:pouring temperature1680"C, shell temperature1100癈, argon flow rate30ml/s. choosing the corundum powder/sand for the type of shell surface layer, solidification and sprue cup ash.Practice results with the above process and technology of production show that the casting surface does not pits, sticky sand, oxidation defects; Shell does not delamination. peeling, cracking phenomenon:At the same time casting also does not appear cold shuts, shrinkage porosity, shrinkage cavity and floating core delects.In this paper,some test results for the castings and the sample show that:(1) The test of frozen core leach show that mandrel stripping effect with the ceramic core saturation water8hours,-10癈frozen6hours and hydrofluoric acid soaking for6hours is frozen stripping remarkable effect and short cycle comparing with hydrofluoric acid directly soaking20hour.(2) Element loss test shows that in1692癈deoxidation3environment,75kg of nickel base alloy need to add Al, Ti, Nb of0.6kg,0.3kg,1.5kg.Subsequent, test results of chemical composition further confirms that the elements of environment,the sequence and weight are reasonable.(3) The castings with the tensile test, hardness measurement,water pressure test,nondestructive flaw detection, heat treatment, microscopic analysis show that without test failure,mechanical properties of castings meets requirement.In short,with above process and technical conditions,non vacuum melting and casting high temperature nickel base alloy is feasible.