Design and verification of pressure curve for anti-gravity casting of nickel-base superalloy

Abstract

In view of the shortage of conventional design methods of pressure curve in the anti-gravity precision casting and taking the structural characteristics of the casting with variable cross-sections into account, automatic calculation of cross-sectional areas was implemented for the casting and gating system by the secondary development of CAD software, and quantitatively describing the variable feature of cross-sections of casting was realized. Based on Bernoulli and flow conservation equations，the relationship between the filling pressure and the rising speed of metal liquid level was deduced. A new design method of pressure curve based on the automatic calculation of cross-sectional areas of the casting was proposed. The simulation results of anti-gravity casting for nickel-based superalloy demonstrate that, compared with the pressure curve of the conventional design method，the new curve can reduce the peak value of filling speed from 0.611 m/s to 0.439 m/s at the minimum cross-sectional area，the falling range of which is 28.15%. It meant that the new method can effectively avoid the shock and splash of liquid metal，meanwhile，shorten the filling time，then the filling process is fast and stable. The hydraulic experiment and pouring experiment show that the new pressure curve has a smoother filling liquid level and can effectively avoid casting defects. Therefore，it proves the effectiveness of the new pressure curve design method and provides a basis for rational design of anti-gravity pressure curve.

Keywords

• nickel-base superalloy
• anti-gravity casting
• pressure curve
• variable cross-section
• numerical simulation