Abstract: A process for heat treating metal workpieces contains with respect to an efficient process control the following successive operations following directly one after the other: a heating phase; an enrichment phase; a first cooling phase; a bonding phase; a second cooling phase; and a concluding quenching phase. Workpieces processed by a method of this type are distinguished by a comparatively great fatigue limit and fatigue strength with simultaneous high resistance to wear and tear.

Abstract: A double carboaustempering combined with a martensite-producing quench provides plain-carbon and low alloy steel power transmission shafts with a carbon-rich exterior having a martensite and bainite microstructure and a substantially bainite interior. The shafts offer increased fatigue resistance.

Abstract: A rocker arm 1 made of sheet metal is formed so that Vickers hardness Hv of the surface layer portion 9a of the valve stem receiver 9 is set at Hv 650 to 800 and a quantity of the retained austenite ?R is set at 25 to 35 vol %.

Abstract: Disclosed is a process for producing a retainer for a constant velocity joint for automobiles or the like, which has improved flexural strength properties without sacrificing the machinability, using a steel corresponding to SCr 415 (JIS) or SCM 415 (JIS). This production process comprises the steps of: providing a steel comprising by weight carbon (C): 0.10 to 0.25%, silicon (Si): 0.03 to 0.15%, manganese (Mn): 0.20 to 0.60%, sulfur (S): 0.003 to 0.030%, chromium (Cr): 1.00 to 1.50%, titanium (Ti): 0.05 to 0.20%, boron (B): 0.0005 to 0.0050%, and nitrogen (N): not more than 0.01% with the balance consisting of iron (Fe) and inevitable impurities; hot forging the steel at a heating temperature of 1000 to 1100° C. to prepare a forged product having a Rockwell hardness of not more than 88 HRB; machining and optionally piercing the forged product; carburizing and quenching and tempering the machined steel to attain an effective case depth of 0.4 to 0.

Abstract: A composition for nitrocarburizing stainless steel parts and a method for producing a nitride or hard case on such parts using the composition, are provided. The composition includes alkali metal cyanate and alkali metal carbonate, wherein the cyanate ion is present in a weight percentage of greater than 45% and less than 55.2%. The composition is fused and maintained between about 750° F. and about 950° F. depending upon the type of stainless steel to be treated. The workpiece is immersed in the fused bath and left in until a satisfactory compound layer or case is formed. With austenitic stainless steel, the piece is immersed from about four hours to about six hours at temperatures between about 750° F. and about 950° F., preferably between 750° F. and 850° F. to maintain corrosion resistance. With 400 series stainless steel, increased corrosion resistance is achieved by immersion for between four and six hours at 950° F.

Abstract: Disclosed is a process for producing an inner race for a constant velocity joint comprising the steps of: providing a steel comprising by weight carbon 0.10 to 0.25%, silicon 0.03 to 0.15%, manganese 0.20 to 0.60%, sulfur 0.003 to 0.030%, chromium 1.00 to 1.50%, titanium 0.05 to 0.20%, boron 0.0005 to 0.0050%, and nitrogen not more than 0.01% with the balance consisting of iron and impurities; hot rolling or hot forging the steel, to prepare a rolled/forged product; cold forging and machining the rolled/forged product; and carburizing, quenching, and tempering the machined rolled/forged product so that the treated steel satisfies an effective case depth of 0.4 to 0.9 mm, a thickness of abnormal-carburizing layer of not more than 15 &mgr;m, and an austenite grain size number as specified in JIS G 0551 of not less than 7.

Abstract: A method of heat treating steel for use in transmission gears of a vehicle including the steps of carburizing the steel to 900-950.degree. C. quenching the carburizing steel at 830-850.degree. C., reheating the steel with ammonia gas to a temperature of 800-900.degree. C., and fusing the reheated steel at a temperature of 150-230.degree. C. for providing excellent anti-abrasion, contact fatigue strength and blending fatigue strength properties, thereby controlling the quality of steel in a furnace.

Abstract: A bearing component is prepared from a carburazing steel and having a surface hardness of 63 to 67 in terms of Rockwell hardness C and a surface retained austenite content of at least 20% to less than 25%. The bearing component is produced by a process including the step of carburizing and quenching a bearing component workpiece prepared from a carburizing steel and machined to a predetermined shape, the step of subjecting the resulting workpiece to a preliminary tempering treatment, the step of subjecting the tempered workpiece to a sub-zero treatment and the step of subjecting the treated workpiece to a main tempering treatment. Further, the bearing component is produced by another process including the step of carburizing and quenching a bearing component workpiece prepared from a carburizing steel and machined to a predetermined shape, the step of subjecting the resulting workpiece to a secondary hardening treatment and the step of subjecting the hardened workpiece to a main tempering treatment.