定向凝固镍基高温合金叶片榫齿高效深切成型磨削

High Efficiency Deep Grinding of Directional Solidified Nickel-Based Superalloy Turbine Blade Root

针对定向凝固镍基高温合金DZ125叶片榫齿，采用电镀成型CBN砂轮对其进行了高效深切磨削（High efficieney deep grinding，HEDG）试验，对磨削比能及工件表面完整性进行了分析。结果显示，在保持速比（Us／‰）不变时，提高磨削速度饥可有效降低磨削比能，提高平均材料去除率。磨削比能表现出“尺寸效应”，其值最终稳定在40～60J／mm^3之间；在相同的平均材料去除率下，磨削比能随着磨削深度的增大而上升；在相同的单颗磨粒切厚下，磨削深度的差异对磨削比能的影响较小。对试验中最大平均材料去除率下获得的工件表面质量进行分析发现，已加工工件表面不同区域磨削纹理均很清晰，无皱叠及犁沟两侧翻起等现象；表层金相显微组织基本无变化，未发现相变、撕裂及晶粒扭曲现象；工件表层加工硬化程度为7．7％～19％，深度为40μm。结果显示了HEDG在高效磨削DZ125叶片榫齿中推广应用的潜力，并为其实际生产中磨削参数的选择提供了参考。

In view of the poor machinability of turbine blade root made of directional solidified nickel- based superalloy DZ125, high efficiency deep grinding（HEDG） process is conducted to analyze specific grinding energy and surface integrity with profiled electroplated CBN grinding wheel. The result shows that higher grinding speed vs can lower the specific grinding energy effectively when the speed ratio （vs/ v;） keeps constant. The specific grinding energy decreases with the increasing mean material removal rate and finally remains in range of 40--60 J/ram3. Under the same mean material removal rate, the specific grinding energy increases with the decreasing depth of cut. However, the difference of depth of cut has little effect on the specific grinding energy with the same undeformed chip thickness. The sur- face quality of the workpiece obtained under the highest mean material removal rate is analyzed. The surface texture is clear, and does not present wrinkles and ploughing marks. The phase transition and grain distortion are not observed from the metallographic microstructure. The degree of work hardening is in range of 7.7%--19%, and the hardening depth is about 40μm. The result reveals the potential of HEDG in the high efficiency machining of turbine blade root DZ125, and provides reference for future application.