Machinability and grindability of high-carbon tool steel manufactured by powder bed fusion electron beam

Paper i proceeding, 2026

Additive manufacturing (AM) enables the production of complex near-net-shaped components; however, limitations in surface integrity and dimensional accuracy often necessitate post-processing such as heat treatment and machining to achieve functional performance. This study investigates the machinability and grindability of Vibenite® 280, a high-speed tool steel manufactured using Powder Bed Fusion–Electron Beam (PBF-EB) process. In the hot-isostatic-pressed (HIPed) and heat-treated condition, Vibenite® 280 exhibits a hardness of ~68 HRC (930 HV1) and its microstructure containing ~20 vol.% V-, Mo-, and W-rich carbides, posing significant challenges for precision finishing. Grinding trials using Al₂O₃ and cubic boron nitride (CBN) wheels demonstrated that CBN provided superior process stability, thermal robustness, and surface integrity, achieving a Ra ~0.3 µm and high G-ratios without thermal damage, even at elevated specific grinding energies. However, the poor as-built surface quality and dimensional deviations required a pre-grinding step prior to finishing. Hard turning tests revealed that coated cemented carbide inserts offered the best compromise between tool wear and surface finish, though chipping and accelerated wear at higher feeds remained problematic. Residual stress analysis indicated beneficial compressive states with a characteristic hook-shaped profile after hard turning, supporting improved fatigue performance. Overall, the findings confirm the feasibility of precision machining Vibenite® 280 in its hardened condition, enabling its application in demanding environments requiring exceptional wear resistance and dimensional accuracy.