Improved machinability in hard milling and strategies for steel development

The synergetic advantage of tailoring alloyed steels to improve their machinability in the hardened (30 similar to 55HRC) state is the focus here. Results from milling tests and systematic study of steel microstructure and tool wear mechanisms using high resolution microscopy (FEG-SEM) and EDS clearly indicates that traditional machinability improvement treatments are not always adequate here. In high alloyed hot working steels, suitable primary carbides distribution could be better than inclusion modification. In low alloyed steels secondary carbide density appears to be critical and correlates well with machinability. The study also points to strategies for steel development and their efficient hard milling.