Novel Surface Heat Treatment that Effectively Uses Nitrogen

摘要

Gas carburizing with quenching is one of the most useful heat treatment process for steel parts. However, distortion occurs after quenching. A novel heat treatment process named "N-QUENCH" for solving this problem was developed. In N-QUENCH, nitrogen is infiltrated into the steel parts in austenite phase, and then is quenched to harden. The N-QUENCH process can also be applied to cheap low carbon steel such as the Cold Rolled Carbon Steel Sheet In this study, the effectiveness of N-QUENCH was examined, and structure, hardness and nitrogen concentration profiles were observed. Also, distortion and tribological properties were examined. The effective case depth (ECD) in N-QUENCH, is larger than that ECD of gas nitrocarburizing for same period of time. Distortion of N-QUENCH is much smaller than that of gas carbonitriding, and it is almost equal with that of gas nitrocarburizing. The seizure load is same as with other heat treatment processes. The wear loss of N-QUENCH is a lower, in the amount of about 1/2 that of the carbonitrided specimen and 1/3 that of the gas nitrocarburized specimen. The N-QUENCH is an effective heat treatment process for parts which require wear resistance. The tempering softening resistance is improved by nitrogen infiltratioa.