Method for heat treating a steel component (28, 36) comprising the steps of: a) carbonitriding the steel component (28, 36) at a temperature of 930-970 C., b) cooling the steel component (28, 36), d) re-heating the steel component (28, 36) to a temperature of 780-820 C. and d) quenching the steel component (28, 36). The method comprises the step of either e) performing a bainite transformation at a temperature just above the martensite formation temperature, transforming 25-99% of the austenite into bainite at the temperature and then increasing the temperature to speed up the transformation of the remaining austenite into bainite, or f) holding the steel component (28, 36) at an initial temperature (T.sub.1) above the initial martensite formation temperature (Ms), and lowering the initial temperature (T.sub.1) to a temperature (T.sub.2) that is below the initial martensite formation temperature (Ms) but above the actual martensite formation temperature during the bainite transformation.

Method for heat treating a steel component (28, 36) comprising the steps of: a) carbonitriding the steel component (28, 36) at a temperature of 930-970 C., b) cooling the steel component (28, 36), d) re-heating the steel component (28, 36) to a temperature of 780-820 C. and d) quenching the steel component (28, 36). The method comprises the step of either e) performing a bainite transformation at a temperature just above the martensite formation temperature, transforming 25-99% of the austenite into bainite at the temperature and then increasing the temperature to speed up the transformation of the remaining austenite into bainite, or f) holding the steel component (28, 36) at an initial temperature (T.sub.1) above the initial martensite formation temperature (Ms), and lowering the initial temperature (T.sub.1) to a temperature (T.sub.2) that is below the initial martensite formation temperature (Ms) but above the actual martensite formation temperature during the bainite transformation.

A method for producing a rolling bearing component includes forming the rolling bearing component from a 100CrMnSi6-4 or 100Cr6 rolling bearing steel, heating the rolling bearing component, quenching the rolling bearing component, heating the rolling bearing component and holding the rolling bearing component. The rolling bearing component to heated to an austenitizing temperature to form an austenitic microstructure. The rolling bearing component is quenched in a hot salt bath to a first temperature of between 170? C. and 200? C. such that there is a pearlitic or ferritic microstructure in a core region of the rolling bearing component. The rolling bearing component is heated to a second temperature between 220? C. and 280? C. The rolling bearing component is held at the second temperature for a holding time of at least 7 hours such that there is a predominantly bainitic microstructure formed on a surface of the rolling bearing component.

An apparatus for imparting compressive residual stress to at least a surface portion of a first plurality of balls includes a first body having a first surface, the first surface including a smooth contact portion, the smooth contact portion being substantially flat or convex and having a surface hardness greater than or equal to the initial surface hardness of the balls. The apparatus also includes a second body having a second surface, the first surface overlying the second surface, and at least one drive operably connected to the first body or to the second body and configured to move one of the first and second bodies relative to the other body at a substantially fixed distance, the at least one drive also being configured to move the first body toward the second body with a force or to move the second body toward the first body with the force.

A steel alloy for a bearing, the alloy having a composition comprising: (a) from 0.5 to 0.9 wt. % carbon, (b) from 1.2 to 1.8 wt. % silicon, (c) from 1.1 to 1.7 wt. % manganese, (d) from 0.7 to 1.3 wt. % chromium, (e) from 0.05 to 0.6 wt. % molybdenum, and optionally any of: (f1) from 0 to 0.25 wt. % nickel, (f2) from 0 to 0.02 wt. % vanadium, (f3) from 0 to 0.05 wt. % aluminium, (f4) from 0 to 0.3 wt. % copper, (f5) from 0 to 0.5 wt. % cobalt, (f6) from 0 to 0.1 wt. % niobium, (f7) from 0 to 0.1 wt. % tantalum, (f7) from 0 to 150 ppm nitrogen, (f8) from 0 to 50 ppm calcium, and (f9) the balance iron, together with any unavoidable impurities, wherein the steel alloy has a microstructure comprising bainitic ferrite and retained austenite, and a hardness (Vickers) of at least 650 HV.

A steel alloy for a bearing, the alloy having a composition comprising: (a) from 0.5 to 0.9 wt. % carbon, (b) from 1.2 to 1.8 wt. % silicon, (c) from 1.1 to 1.7 wt. % manganese, (d) from 0.7 to 1.3 wt. % chromium, (e) from 0.05 to 0.6 wt. % molybdenum, and optionally any of: (f1) from 0 to 0.25 wt. % nickel, (f2) from 0 to 0.02 wt. % vanadium, (f3) from 0 to 0.05 wt. % aluminium, (f4) from 0 to 0.3 wt. % copper, (f5) from 0 to 0.5 wt. % cobalt, (f6) from 0 to 0.1 wt. % niobium, (f7) from 0 to 0.1 wt. % tantalum, (f7) from 0 to 150 ppm nitrogen, (f8) from 0 to 50 ppm calcium, and (f9) the balance iron, together with any unavoidable impurities, wherein the steel alloy has a microstructure comprising bainitic ferrite and retained austenite, and a hardness (Vickers) of at least 650 HV.

A size hardening heat treatment process for steel parts of a plate, cylindrical or spherical shape and using low or specified hardenability steel compositions which are through surface heated and very rapidly quenched to produce case hardening of the part. A set of graphs are provided which depict the relationship between the depth of hardening and the dimension of the part for each of a series of critical, i.e., ideal diameter values which allow producing a depth of hardening of a particular part by a proper selection of the DI value of the part. The DI values are calculated by a formula which allows a range of DI values to be created by varying the components of the steel as set out in the formula. The formula also insures a fine grain size to be created by the process to prevent cracking by the very rapid quenching required. A list of elements allowed in the steel but limited by a % mass set out for each component. A particular depth of hardening desired can be produced for a given part of a shape and dimension appearing in the graphs by composing the steel so that the DI is that critical which will produce the desired depth of hardening when the part is heated by through the surface heating and then very rapidly quenched.

A size hardening heat treatment process for steel parts of a plate, cylindrical or spherical shape and using low or specified hardenability steel compositions which are through surface heated and very rapidly quenched to produce case hardening of the part. A set of graphs are provided which depict the relationship between the depth of hardening and the dimension of the part for each of a series of critical, i.e., ideal diameter values which allow producing a depth of hardening of a particular part by a proper selection of the DI value of the part. The DI values are calculated by a formula which allows a range of DI values to be created by varying the components of the steel as set out in the formula. The formula also insures a fine grain size to be created by the process to prevent cracking by the very rapid quenching required. A list of elements allowed in the steel but limited by a % mass set out for each component. A particular depth of hardening desired can be produced for a given part of a shape and dimension appearing in the graphs by composing the steel so that the DI is that critical which will produce the desired depth of hardening when the part is heated by through the surface heating and then very rapidly quenched.

A method for heat treating a steel component, which comprises the steps of: (a) carbonitriding the steel component, and (b) austenitically nitrocarburizing the steel component.

A method for heat treating a steel component, which comprises the steps of: (a) carbonitriding the steel component, and (b) austenitically nitrocarburizing the steel component.