Effect of cutting fluid on high strain rate dynamic mechanical property and cutting performance of nickel based superalloy

Cutting fluids are essential for the machining of difficult-to-cut materials in production. In addition to four basic functions including cooling, lubrication, cleaning, and antirust, cutting fluids also have an effect on the reduction of hardness and ductility of materials. Focused on the effect of cutting fluid composition in the material deformation processes, the influence of two universal cutting fluids (denoted as Blasocut and E709) on high strain rate dynamic mechanical properties of Ni-based superalloy was experimentally investigated and verified by cutting process. The shear stress-shear strain curve, maximum shear stress and shear failure stress, milling force as well as chip formation were systematically investigated. It is indicated that the results from Split Hopkinson Pressure Bar tests are consistent with those from cutting experiments. The Rehbinder effect for the samples under E709 conditions is more significant and the stress fluctuation is the largest, which is up to 14%. Brittle fracture exists under a narrow shear bandwidth 100 μm with high strain rate 10 × 10⁴ s⁻¹, while ductile fracture occurs under a wide shear bandwidth 400 μm with low strain rate 3 × 10⁴ s⁻¹. The cutting force amplitude under E709 is larger than that of Blasocut. The chip burrs under E709 and water are more severe than those under Blasocut. This research reveal significant connection between the cutting fluids and the dynamic mechanical properties or the cutting performance of the metal, which is also helpful to the control of mechanical properties and fatigue resistance of the machined surface.