Effect Of Leach Technics On Microstructure And Properties Of Three Kinds Of Superalloy

With the rapid development of aviation industry, more and more high demand by the superalloys which are applied for blades are required. Advanced aero engines and gas turbines need the aero engine blades with the complex inner cavity which are made by ceramic core, but we don’t know about what’s the effect of microsructure and mechanical properties of superalloys after leach technics. So effects of leach technics on microsructure and mechanical properties of three superalloys are discussed in this paper. It is of great significance.Three superalloys (DZ40M, DZ125L, K417) are respectively tacled by leach technics of alumina-based ceramic core or silica-based ceramic core, and then studying their tensile and lasting performance. The effect of microstructure and mechanical properties of applied for directional and hollow blades are studied by means of EDS、XRD、SEMete for the same leach technics of different time immerse in core leach liquid and the same time immerse in core leach liquid but different leach technics.The results show that there are no more changes of fracture morphology and tensile and lasting performances for three superalloys after being tackled by leach technics of silica-based ceramic core. After being tackled by leach technics of alumina-based ceramic core, properties of tensile and lasting of DZ40M sharply decrease, life of lasting even fall to less than an hour, the way of fracture transform brittle rupture; The property of tensile of K417has little change, the life of lasting begin to decrease as the lengthen of soaking time; There are no apparent change in property of tensile、lasting and the way of fracture. And then making gas analysis for three alloys, the results showed that hydrogen penetrate into the alloy after leach technics of alumina-based ceramic core, and to analyze the fracture of the alloy. There are hydrogen embrittlement sensitivity for three alloys, the alloy of DZ40M is the most serious, K417are the second, and the DZ125L has less influence.Some experimental results are showed by XRD. There are no crossion products on the surface of DZ40M, DZ125L and K417after being tackled by silica-based depoling liquid, further more the oxide layer is thin. The layers of K417and DZ40M become thicker after being tackled by alumina-based depoling liquid, the corrosion products mainly contain oxide of Cr,Ni and Ti.