Machining characteristics of microalloyed forging steels

AbstractIn this paper the machinability of forging steel grades, microalloyed with vanadium for precipitation hardening and used in the air-cooled condition, are compared with those of hardened and tempered steel grades. Standard laboratory tests, employing both high-speed-steel and cemented carbide tooling, have been used. In most instances, microalloyed steel proved to be at least as machinable as hardened and tempered steel grades of similar strength level. However, because of a higher dependence of machinability on workpiece hardness, microalloyed steels may have inferior machinability to hardened and tempered alloy steels, at tensile-strength levels above 1000 MN m−2. This higher dependence on workpiece hardness has been investigated using a range of experimental techniques and a tentative mechanism has been proposed. Finally, compositional adjustments have been proposed, which might improve the machinability of microalloyed steels and thus eliminate this one potential problem area.