Papers by Keyword: FGH95

Abstract: The superalloy parts in the aeronautical field demand high reliability, which is largely related to surface integrity. Surface integrity generally includes three parameters, such as geometric parameter, mechanical parameter and metallurgical parameter. The paper presents the influence of cutting speed on surface plastic deformation and white layer formation through orthogonal milling of FGH95 superally material. The influence of cutting speed on grain refinement of machined surface is also investigated. It is found that cutting speed has significantly effect on the surface metallurgical characteristic microstructure. The increasing of cutting speed creates severer plastic deformation. Surface plastic shear strain increases with the increasing of cutting speed, while the depth of plastic deformation decreases on contrary. White layer thickness is increased with the increasing of cutting speed. Through statistical analysis for grains number, it can be drawn that the higher the cutting speed, the more serious grains refinement.

Abstract: Tool flank wear has the significant effects on machined surface integrity. The influences of tool flank wear on the cutting forces, surface roughness, microhardness and white layer thickness are investigated in this paper through orthogonal milling experiments. FGH95 powder metallurgy (PM) superalloys are machined with coated cemented carbide tools in the milling experiments. The experiment results show that with the increasing of tool flank wear, cutting force, surface roughness and white layer thickness increase. However, the machined surfaces micro-hardness aggravates with the increase of tool flank wear. It is found that, the machined surface roughness, micro-hardness and white layer increase dramatically especially when the tool flank wear exceeds 0.3mm. A conclusion is then be drawn that, the maximum acceptable tool flank wear land is 0.3mm from the view point of surface integrity when FGH95 PM superalloy is machined with coated cemented carbide tools.

Abstract: FGH95 nickel-based superalloy is produced by powder metallurgy (PM) processing for aerospace applications. Due to lower thermal conductivity, work hardening tendency during machining, and intensive adhesion to the surface of the tooling under operation, machining of FGH95 alloy is a significant challenges. The FGH95 machining process will induce substantial amount of plastic deformation in the surface and subsurface of the workpiece. A theoretical model is developed to predict the plastic deformation in machined surface of FGH95 superalloy. Experimental results are also applied to analyze the influence of cutting speed on plastic deformation in machined surface of FGH95. It is found that cutting speed has significantly effect on the plastic deformation in the machined surface. The increasing the cutting speed creates severer plastic deformation. Surface plastic shear strain increases with the increases of cutting speed, while the depth of plastic deformation decreases contrary.

Abstract: FGH95 is one kind of high-strength, thermal-resistant nickel-based superalloys fabricated by powder metallurgy (PM). It plays an increasingly important role in the development and manufacture of turbine discs. Due to the extreme toughness and work hardening characteristics of this kind of superalloy, the problem of machining FGH95 is one of ever-increasing magnitudes. This paper investigates the influence of cutting parameters on the cutting force, cutting temperature and tool wear during the end milling of PM nickel-based superalloy FGH95. The empirical formula for cutting force and cutting temperature of FGH95 are given out. Experimental results show that the cutting speed among milling parameters has the greatest influence on cutting forces and cutting temperatures. It is shown that the major tool wear mechanisms are combination interactions of abrasive wear, adhesion wear, micro-breakout and chipping.