초록 ▼

A stainless steel bearing component containing in excess of 11% chromium and between 0.05% and 0.50% carbon is case-hardened by introducing carbon or nitrogen into the surface of the race using a plasma process. The component is heated in a chamber from which air is evacuated. There it is bombarded

A stainless steel bearing component containing in excess of 11% chromium and between 0.05% and 0.50% carbon is case-hardened by introducing carbon or nitrogen into the surface of the race using a plasma process. The component is heated in a chamber from which air is evacuated. There it is bombarded with hydrogen ions to clean its surface. Next, while the component remains at an elevated temperature, a gas containing carbon or nitrogen or both is introduced into the chamber where it exists at a relatively low pressure on the order of 2-9 torr. A plasma is produced intermittently, and it causes carbon or nitrogen or both to diffuse intio the surface of the component and create a case containing a greater proportion of carbon or nitrogen than the underlying core. Thereafter, the component is cooled and with most stainless steels this may be acheived by quenching in oil. Where the case is enriched in carbon, the component is thereafter reheated to a temperature where its core exists as single phase austenite and held at that temperature to effect a soak. An oil quench follows and it converts much of the austenite to martensite. The quench in turn may be followed by cryogenic cooling to convert retained sustenite into martensite. After assuming ambient temperature, the component is again heated to temper the hardened case.

대표청구항 ▼

[ What is claimed is:] [6.] A process for producing a corrosion resistant bearing component, said process comprising cleaning the surface of a steel shape having the configuration generally required for the component, the steel of the shape comprising iron, less than 0.50% by weight carbon and more

[ What is claimed is:] [6.] A process for producing a corrosion resistant bearing component, said process comprising cleaning the surface of a steel shape having the configuration generally required for the component, the steel of the shape comprising iron, less than 0.50% by weight carbon and more than about 11% by weight chromium; thereafter subjecting the steel shape with its cleaned surface to a plasma containing carbon or nitrogen or both while the shape is at an elevated temperature exceeding 900.degree. F., all for sufficient time to enable carbon or nitrogen or both to diffuse into the shape and create a case over a core, the core having the constituency of the original shape and the case having a greater content of carbon or nitrogen or both than the core, but not exceeding about 0.98% carbon by weight at the surface; and cooling the shape to a temperature less than that at which it existed while being subjected to the plasma.