scope:

In the ongoing strive for light weighting or power densification, high-performance clean steels are showing a significant improvement. As a next step, gear steels that combine several properties, are now proving an interesting alternative. Traditional gear steels achieve their maximum hardness after carburizing and a fast quench. A fast quench usually results in distortion as the part is unavoidably unsymmetrically cooled/quenched. For many gear applications, distortion during heat treatment of final component, can add cost and unwanted hard machining operations. With many components being more sensitive to distortion, especially within electrical vehicles, where NVH becomes even more important, the potential to reduce distortion from heat treatment can be essential. With a new steel composition, that hardens by precipitation hardening (aging around 500°C/950F) low distortion can be attained as a fast quench such as an oil quench is not necessary. This type of steel can be both nitrided and carburized. Costly hard machining can therefore be reduced due to the low distortion. Other interesting properties of this new steel that will be presented in this paper are; good mechanical properties at elevated temperatures and good corrosion and oxidation properties compared to traditional gear steels.