A new family of improved machining gear steels has been developed using calcium deoxidation. Using these steels, the rougher and finisher cutter tool life during gear cutting on automotive differential drive pinions and ring gears has been improved by as much as 70-100%. Currently, calcium deoxidized steels are being used by many automotive gear and axle plants on a production basis and have realized similar improvements in cutter life with resultant substantial cost savings and productivity gains.
These calcium deoxidized steels are fine grained and exhibit identical hardenability, carburizing, and heat treat response as that of the conventional Al-Si deoxidized steels. The mechanical properties such as impact strength, tensile strength, ductility, and fatigue resistance of the calcium deoxidized steels are essentially the same as those of the conventional Al-Si deozidized steels.
The application of calcium deoxidized steels for carburizing as well as through-hardening grades for transmission gears, steering worms, as well as pinion and ring gears used in trucks, tractors, and off-the-road equipment also shows promise of substantial gains in tool life with resultant cost savings and productivity gains.