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 laminated ring for use as a belt in transmitting power in a continuously variable transmission is produced by welding opposite ends of a sheet of maraging steel to produce a plurality of rings, and rolling said rings to a predetermined length. The rings are nitrided in a salt-bath nitriding process by dipping the rings in a molten salt containing 38-46% of CNO− and 1-2% of CN− and heated to a temperature in the range from 480 to 530° C., for a period of time ranging from 10 to 25 minutes. The nitrided rings are finally stacked into a laminated ring.

Abstract: A rolling support device excellent in both of the characteristics of durability and corrosion resistance is provided. The inner ring (1) and the outer ring (2) comprises an austenitic stainless steel and has, on a raceway surface, a carburizing hardened layer containing no substantial carbides at a Vickers hardness (Hv) of 650 or more. The carburizing hardened layer is formed by applying fluoriding and then applying carburizing at a temperature of 540° C. or lower. The rolling element (3) is made of Si3N4.

Abstract: In a method of increasing the wear resistance and the corrosion resistance f opposed bearing surfaces of parts subjected to reciprocal friction, in particular when the product of the pressure distributed over the bearing surfaces by the relative speed of the latter exceeds 0.4 MPa.m/s, thermochemical diffusion of nitrogen is effected by nitriding or nitrocarburizing in a molten salt bath at a temperature of 570.degree. C..+-.15.degree. C. followed by an oxidizing or phosphating surface chemical reaction providing resistance to wet corrosion. The nitriding or nitrocarburizing molten salt bath is made up of alkaline carbonates and cyanates and further contains sulfur-containing substances in the following percentages by weight:30%<CNO.sup.- <45%15%<CO.sub.3.sup.2- <25%15%<Na.sup.+ <25%20%<K.sup.+ <30%1%<Li.sup.+ <6%1 ppm<S.sup.2- <100 ppmThe time for which parts are immersed in the bath is between 15 minutes and 45 minutes.

Abstract: Precision ferrous metal parts subject to severe friction and corrosion in e are nitrided, preferably in a bath of molten salts based on CNO.sup.- cyanate ions, oxidized, preferably in baths of molten oxidizing alkaline salts, and then impregnated with a hydrophobic wax. A layer after the nitriding and oxidation steps is formed of a close-packed deep sub-layer and a porous superficial sub-layer ranging in thickness between 5 and 25 .mu.m, and exhibiting through pores ranging between 0.2 and 3 .mu.m in diameter. The impregnation wax is an organic compound with a high molecular weight between 500 and 10,000, with a surface tension in the liquid state ranging between 10 and 73 mN/m, the contact angle between the solid phase of the superficial layer and the wax in the liquid state ranging between 0 and 75.degree. C.

Abstract: A method of nitriding nickel alloy comprising steps of holding nickel alloy in an atmosphere of fluorine- or fluoride-containing gas in a heated condition and holding the fluorinated nickel alloy in a nitriding atmosphere in a heated condition to provide the nickel alloy with improved surface hardness by forming a deep uniform nitrided layer on the surface of the nickel alloy.

Abstract: This invention relates to a method of nitriding steel material in a second heat treatment furnace after fluorinating the steel material in a first heat treat furnaceto form a deep and uniform nitrided layer. Then, steel material is treated smoothly by defining the ratio of establishing said both furnaces for fluorinating and niriding on the basis of treating time required for said both treatments since time required for each treatment is different.