The nickel-based superalloy GH4169 is widely applied in the aviation industry due to its outstanding mechanical properties. However, many blades of GH4169 are still produced by milling and manual polishing, which is costly and unreliable. In this article, GH4169 superalloy components manufactured with combination processes of milling, grinding, and polishing were comparatively studied involving surface integrity and fatigue performance. Test results indicate that the final polishing is the most dominant process that influences the high-cycle fatigue life of GH4169 components. Samples produced via cubic boron nitride grinding and numerical control polishing with a diamond-rubber wheel exhibit fatigue limits of 150 MPa higher than the milled and manually polished samples. Cubic boron nitride grinding induces a considerable compressive residual stress profile with a magnitude of -930 MPa and a depth of 200 μm. Milling induces a typical “hook” residual stress profile with 318 MPa at the surface. Polishing affects the machined surface by two ways, the removal effect and the squeezing effect. The squeezing effect induces a shallow compressive residual stress with approximately −1000 MPa, therefore improves the surface condition. However, inevitable omissions, scratches, texture disorders, and knock marks in hand-polishing are the main causes of the unstable high-cycle fatigue life of hand-polished components.
Hot work character of stainless steel is focused on and the technique and operation of heating process of stainless steel are studied in this paper in the aspects of the charging of stainless steel heating furnace, the temperature regulation and control in steel heating process, the detection and control of furnace temperature and heating time, the control of atmosphere and furnace pressure during heating process, and the control of furnace when rolling stopped, etc. And each of them has significant effect on the production of stainless steel.
The wear process of electroplated CBN grinding wheel is difficult to predict and control because of the lack of unified evaluation index of wear degree. This paper investigates the service life cycle of electroplated CBN grinding wheel in grinding of nickel-based superalloy GH4169. The evolution of topography of grinding wheel, diameter of grinding wheel, grinding force and surface roughness are tracked in the wear process. Using the analytic hierarchy process (AHP), the optimal evaluation index of service life of electroplated CBN grinding wheel is proposed.
To solve the true stress strain of Cr8 steel, a method of cone inversion is used to deal with the high temperature tensile data. Based on the precise determination and description of sample size, the test data is analyzed in the SSC(Stress strain calculator) software developed on MATLAB, and the true stress strain curve of Cr8 is drew. The true stress strain curve calculated by this method is smooth and continuous, and more identical to the principle of metal elastic-plastic deformation process, which shows a good promotion value.
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