Profile grinding of DZ125 nickel-based superalloy: Grinding heat, temperature field, and surface quality

Abstract

• Increase of grinding speed and undeformed chip thickness decreases grinding heat. • Temperature field is characterized by experiments and simulation. • DZ125 is well ground by HEDG with good quality and residual compressive stress. • DZ125 blade root is ground with material removal rate over 50 mm 3 /(mm·s). During the high-efficiency deep grinding of a turbine blade root, localized thermal damage of the profile surface could easily occur owing to the complexity of the grinding dynamics and cooling conditions in the grinding zone. Therefore, it is worthwhile to investigate the generation of the grinding heat, the grinding temperature and its distribution, and the grinding surface quality, particularly for superalloys used to produce aero-turbine blades. In this study, the specific grinding energy and grinding heat flux during the profile grinding of a fir tree-shaped root of a DZ125 superalloy turbine blade were investigated. The grinding temperature at four points on the profile were measured and the results were used to conduct a three-dimensional simulation to analyze the temperature distribution on the machined surface and in the direction of the cutting depth. The effects of the heat source shape and contact length on the temperature distribution were also examined. A moderately high material removal rate was found to be beneficial to the surface quality, with a maximum material removal rate of 50.6 mm 3 /mm·s producing a surface roughness of Ra 0.6 μm without saturation or microstructural changes. Residual compressive stress was also achieved on the ground surface.