| Superalloy blade is one of key components of engine. The microstructure ofsurface and interior and mechanical properties of blade would directly influenceits general properties. Because of superalloy blade serving at high temperature,alternative stress serious conditions, the superalloy blade made by investmentprecision casting is required not only surface perfect but also fine grain toresistance fatigue, and density microstructure to resistance elevated temperaturecreep. Due to harsh working conditions of 1-grade turbine blades, the grain ofblade surface grain size is required below 4 grade, and the blade body is net-shape casting. Complex shape and thin wall of blade make casting process moredifficult. So, in this paper, manufacturing process and acceptance level of turbineworking blade are introduced, and refining mechanism of blade surface grain areresearched. And new shell preparation process and pouring process optimized arepresented.The results of surface grain refining process show that the main cause ofinfluence on superalloy blade grain size is that there is SiO2 film at refiningceramic shell internal surface. The SiO2 film can be removed by second hightemperature baking ceramic shell in electric furnace. After baking, internalsurface ceramic shell endothermic reaction will be intensified, which to decreasetemperature at liquid phase and to result in lack of casting. The method ofresolving is reducing the amount of cobalt oxide from 20％to5％.The results of optimum of new process indicate that the producing cost willbe decreased by reducing the amount of cobalt oxide from 20％to 1％. It isappropriate to cut down craftwork and shorten the production cycle by incorporation with refining baking and first ceramic shell baking and secondceramic shell baking to one step high temperature baking. On the base ofensuring intensity, the production cost is reduced by decreasing layer number ofshell daubing, from 7 layers to 5 layers. The optimum casting process is obtained,namely temperature (1485±5)℃, casting rate (0.6～0.8)s/kg.
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