Using Response Surface Methodology of Deep Hole Electrical Discharge Machining Study of Nickel-Base Alloy Inconel-718

The blades in the high-pressure turbine section of engines of modern aerospace and defense industries need to be drilled for pressurization. The milling and drilling of nickel-base material Inconel-718 are likely to create tool wear and tear, so the drilling process of milling is replaced by deep hole electrical discharge machining (EDM) extensively. However, the EDM creates reaming or overcut phenomenon, so reducing overcut by parameter optimization is an important study. This study used will use response surface methodology to establish the influencing factors of machining parameters in the hole enlargement and machining speed. The experimental results show that the main influencing factor in the nickel-base alloy deep hole EDM is the discharge voltage (V), the secondary factor is the discharge current (I). The hole enlargement of processed hole without optimization is 60um~100um. The DOE is used for hole enlargement measurement and machining speed measurement to design important parameters, and to predict experiment data analysis. The half normal probability graph, Pareto chart and Analysis of variance (ANOVA) are used to learn about the significant factors of parameters and the influence of interaction. The outlet value of optimized parameters is relatively uniform, and the hole morphology is relatively free of residue stacking. Finally, the inlet and outlet results are improved by 17.9% compared with the original parameters. The optimization parameter value predicted by the fitted model is 0.0392mm, and the optimized upper and lower holes validation experiment machining error is 0.0380mm, and the values are quite close, proving that this prediction model is accurate. The model prediction of this DOE can enhance the applied technology of deep hole EDM for nickel-base alloy.

Study on laser powder bed fusion of nickel-base alloy of G-surface structure: scanning strategy, properties and compression properties

Aiming at laser powder bed fusion of GH3536 nickel base alloy, the effects of different scanning strategies on microstructure, porosity and mechanical properties were explored. In the aspect of microstructure and micro hardness of the sample, three scanning strategies had little difference; in the aspect of macro mechanical properties of the sample, the slope subarea scanning was better than the helix and island scanning. On this basis, the slope subarea scanning was selected as the optimal scanning strategy to form the G-surface structure, and the compression performance of G-surface was studied. The results showed that: (1) the compression performance of G-surface structure was smaller than that of solid structure, The compression strength of G-surface can only reach about 20% of solid structure: the average strength value of G-surface is 220 MPa, solid structure is 1.1 GMpa; while G-surface structure had a smooth compression curve, which indicated the good energy absorption characteristics; (2) with the increase of wall thickness, the mechanical performance of G-surface structure was also enhanced, while the energy absorption capacity was constantly reduced; (3) with the same wall thickness, the compression performance of sample in building direction (BD) is higher than that in horizontal direction (HD).