Abstract: A reduced-pressure heat treatment jig is used for supporting a workpiece of iron when the workpiece is subjected to heat treatment in a reduced-pressure atmosphere in which pressure is reduced compared to atmospheric pressure. The jig is formed of an iron material and is formed with a film on at least a contact surface with the workpiece, the film being formed of a material which persists during the heat treatment. The film preferably includes a metal oxide having an evaporating temperature higher than the heat treatment temperature in the reduced-pressure atmosphere. The film preferably contains aluminum oxide.

Abstract: A technique includes providing a tool to be deployed in a well to perform a downhole function. The downhole function requires a minimum structural integrity for an element of the tool. The technique includes forming at least part of the element from a ferrous alloy and charging the alloy with hydrogen cause the element to be more prone to cracking than before the hydrogen charging.

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: In a method of producing an iron-based alloy containing chromium carbide, pieces of cemented carbide are added to an iron-based melt containing carbon, e.g. cast iron. Chromium, which regulates the solution of WC into the melt, is also added. The molten alloy is then cast. An alloy comprising chromium-tungsten-carbide in a ferrous matrix is produced. Uses of the alloy are claimed.

Abstract: There is provided an inexpensive rolling element used under high interface pressure such as induction hardened gears, the rolling element being improved in the seizure resistance of its tooth flanks and having a temper hardness of HRC 50 or more at 300° C. To this end, the rolling element is made from a steel material containing at least 0.45 to 1.5 wt % C and one or more alloy elements selected from 0.1 to 0.5 wt % V and 0.3 to 1.5 wt % Cr, and has a rolling contact surface layer having a structure tempered at low temperature in which 2 to 18% by volume cementite disperses in a martensite parent phase formed by induction heating and cooling and containing 0.25 to 0.8 wt % carbon solid-dissolving therein.

Abstract: A method of gas carburizing is carried out at a carburizing temperature which is not higher than a peritectic point temperature at which ? iron and liquid phase are transformed into ? iron and not less than a eutectic point temperature at which liquid phase is transformed into ? iron and cementite. The method comprises the step of predetermining the limiting carburizing conditions at which the surface layer of a sample of a steel treatment object present in a carburizing atmosphere is austenitized without melting and the step of gas carburizing the treatment object under carburizing conditions which are set so as not to contradict the limiting carburizing conditions, at a carburizing temperature which is not higher than the peritectic point temperature and not less than the eutectic point temperature. The limiting carburizing conditions comprise an upper limit value of a partial pressure of carburizing gas at which the surface layer of the sample is austenitized without melting.

Abstract: A surface processing method includes the step of increasing a surface hardness of a metal having a nominal composition that includes about 0.21-0.25 wt % carbon, about 2.9-3.3 wt % chromium, about 11-12 wt % nickel, about 13-14 wt % cobalt, about 1.1-1.3 wt % molybdenum, and a balance of iron from a first hardness to a second hardness. For example, the method is used to produce a surface-hardened component that includes a core section having a first hardness between about 51 HRC and 55 HRC and a case section having a second hardness that is greater than the first hardness.

Abstract: A conventional aluminum killed alloy steel for case hardening of gear(s) and/or shaft components consisting of 0.10 to 0.30 weight % Carbon, 0.15 to 0.35 weight % Silicon, 0.8 to 1.5 weight % Chromium, 0.6 to 1.5 weight % Manganese, 0.017 to 0.040 weight % Aluminum, and balance iron including impurities, produced by vacuum degassing and alike routes. Gear(s) and/or shaft components made by the above steel when treated by modified carbonitriding followed by hard shot peening process provide both superior bending fatigue strength and pitting fatigue life, capable of withstanding higher torque levels and speeds.

Abstract: The invention relates to the use of PVD technique for the application of a low static friction and wear resistant coating consisting essentially of titanium nitride or a diamond-like carbon—DLC, with or without an addition of tungsten carbide, on a stainless steel, in one and the same operation as the surface hardening of the stainless steel. In this way, in one single operation, a low static friction is obtained on a very hard and wear resistant surface. Moreover, the dimensions of the work-piece are maintained unaltered, which makes the invention very useful in the production of, e.g., cam followers, cylinder tubes and piston rods for shock absorbers. The used stainless steel has the following composition (in weight %): carbon max about 0.1; nitrogen max about 0.1; copper from about 0.5 to about 4; chromium from about 10 to about 14; molybdenum from about 0.5 to about 6; nickel from about 7 to about 11; cobalt 0 to about 9; tantalum max about 0.1; niobium max about 0.1; vanadium max 0.

Abstract: A roller member comprising high carbon chromium bearing steel having a carburization treatment. The bearing steel comprising a surface portion defined as a range between a surface of a rolling face of the roller member to a depth where a maximum shearing stress acts thereon, the surface portion containing carbon in a total amount comprising a range of 1.0 to 1.6 wt % and an amount of residual austenite comprising a range of 20 vol % to 35 vol % wherein a compression residual stress of the surface portion comprises a range of 150 to 1000 MPa, wherein a surface hardness of the surface portion comprises a range of 64 or higher in Rockwell C hardness, wherein an amount of carbide precipitate on the surface portion comprises a range of 10% to 25% in an area rate and each carbide particle size comprises a range of 3 ?m or less.

Abstract: A carburizing process for increasing the hardness of a case region of a steel component. In one form the application includes plating the outer surface of a stainless steel component with nickel prior to carburizing. One component includes a stainless steel object having a hardened case substantially free of continuous phase grain boundary carbides.

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 first process of a method of gas carburizing, a steel treatment object in a carburizing atmosphere containing carburizing gas is heated to an initial set temperature which is not higher than a peritectic point at which ? iron and a liquid phase transform into ? iron and not less than a eutectic point at which the liquid phase transforms into ? iron and cementite, such that the surface carbon concentration thereof does not exceed a solid solubility limit. In a second process following the first process, the carburizing temperature is gradually decreased from the initial set temperature such that the surface carbon concentration of the treatment object increases without exceeding the solid solubility limit, and such that the carburized depth of the treatment object increases.

Abstract: The invention relates to components made of steel, more particularly outer joint parts and inner joint parts of constant velocity joints, and to a process of heat treating such components made of steel. The heat treatment operation includes the process stages of nitriding, induction surface layer hardening and tempering, which processes follow one another. As a result of the nitriding operation, the joint parts are provided with a surface layer (15) including nitrides and a diffusion layer (18) positioned thereunderneath. The subsequent induction hardening process causes the diffusion layer (18) to be hardened, so that it comprises good supporting characteristics for supporting the surface layer (15) positioned above same.

Abstract: The present invention is directed to a process for producing pearlite from an iron containing article comprising the steps of, (a) heating an iron containing article comprising at least 50 wt % iron for a time and at a temperature sufficient to convert at least a portion of said iron from a ferritic structure to an austenitic structure, (b) exposing said austenitic structure, for a time sufficient and at a temperature of about 727 to about 900° C., to a carbon supersaturated environment to diffuse carbon into said austenitic structure and (c) cooling said iron containing article to form a continuous pearlite structure.

Abstract: A steel for a high bearing pressure-resistant member, having a high machinability. The steel is formed of a machine structural steel comprising carbon in an amount ranging from 0.15 to 0.25% by weight, silicon in an amount of not less than 0.4% by weight, nickel in an amount ranging from 1 to 3% by weight, chromium in an amount ranging from 1.2 to 3.2% by weight, and molybdenum in an amount ranging from 0.25 to 2.0% by weight. The machine structural steel contains carbide precipitated under a heat treatment for spheroidizing. The carbide has an average particle size of not larger than 1 ?m and the maximum particle size of not larger than 3 ?m.

Abstract: A rolling element for a continuously variable transmission, including a plurality of rolling members having rolling contact portions that come into rolling contact with each other via lubricating oil. At least one of the rolling contact portions includes an outer surface layer having a surface microhardness of not less than Hv 750, a surface residual compressive stress of not less than 1000 MPa and a residual austenite content of not more than 10% by volume.

Abstract: In a first step of a method of gas carburizing, a steel treatment object is heated in a carburizing atmosphere comprising a carburizing gas until the surface carbon concentration of the treatment object reaches the final target value that is not higher than the solid solubility limit at a carburizing temperature that is not higher than the peritectic point, at which steel transforms from &dgr; iron and liquid phase to &ggr; iron, and is not less than the eutectic point, at which steel transforms from liquid phase to &ggr; iron and cementite. In a second step the gas carburizing is advanced after the first step so that the carburizing depth of the treatment object increases while the surface carbon concentration of the treatment object is kept at the final target value by reducing the carbon potential of the carburizing gas with the lapse of time.

Abstract: In the partial thermochemical vacuum treatment of metallic workpieces (1), in particular in the carburization and case hardening of workpieces (1) of case-hardening steel in a carbon-containing atmosphere, surface regions (3, 4, 5, 6) to be treated and surface regions not to be treated abut one another. In order to restrict the surface treatment to the cavities (2) of the workpieces (1) the external surface regions not to be treated are covered by reusable dismountable mould bodies (11) of a temperature-resistant material with at least one mould cavity (15). In this connection the mould body (11) consisting of a lower part (12) and an upper part (13) with openings (12b, 13b) encloses several workpieces (1) in such a way that no treatment takes place on the external surface regions of the workpieces (1). An electrically conducting mould body (11) is suitable in particular for a thermochemical treatment under the action of a plasma. Graphite or CFC is used as material for the mould bodies (11).

Abstract: Steel alloys susceptible to case and core hardening comprise 0.05 to 0.24 wt % carbon; 15 to 28 wt % cobalt and 1.5 to 9.5 wt % in nickel, small percentages of one or more additives: chromium, molybdenum, and vanadium; and the balance iron. Carburized roll form and punch dies and tools made from case hardened steel alloys with a reduced hardness core provide high wear and fatigue resistance as well as improved contact and bending fatigue resistance thereby avoiding premature failure and extending the useful life of such tools.

Abstract: This invention is directed to a process and apparatus for producing high productivity carburizing. A process is introduced that uses a gas mixture made up of CO, H2, CO2, H2O, CH4 and N2, such that the product of the %CO and %H2 is greater than about 1600; the ratio of CO/CO2 is greater than 10; and the ratio of H2/H2O is greater than about 10. The gas mixture is controlled for a short time. A reactor for generating a gas mixture for carburizing steel is also introduced. This reactor is composed of a cylindrically symmetric body; a first central tube containing electrical heating elements for gas flow; a second central tube concentrically disposed around the first central tube; and a plurality of catalyst beds disposed in an annular space in a segmented fashion around the second central tube.

Abstract: This invention is directed to a process and apparatus for producing high productivity carburizing. A process is introduced that uses a gas mixture made up of CO, H2, CO2, H2O, CH4 and N2, such that the product of the % CO and % H2 is greater than about 1600; the ratio of CO/CO2 is greater than 10; and the ratio of H2/H2O is greater than about 10. The gas mixture is controlled for a short time. A reactor for generating a gas mixture for carburizing steel is also introduced. This reactor is composed of a cylindrically symmetric body; a first central tube containing electrical heating elements for gas flow; a second central tube concentrically disposed around the first central tube; and a plurality of catalyst beds disposed in an annular space in a segmented fashion around the second central tube.

Abstract: A method is provided of producing a hardmetal-bonded metal component with an enhanced bond strength. The method comprises the steps of providing an iron-based metal body, mixing and compressing raw material powder of hardmetal and binder powder containing nickel, silicon and boron into a preform, heating and sintering the preform, and applying heat to the sintered body and the iron-based metal body under a state that the sintered body is brought into contact with the iron-based metal body, to thereby cause the sintered body to be bonded to the iron-based metal body. The sintered body and the iron-based metal body are thermally treated at a temperature of 1,000 to 1,200° C. for 30 or more minutes so that boron present in the sintered body is infiltrated into grain boundaries of the iron-based metal body to form a plurality of boride spikes in a bonding interface.

Abstract: The present invention is directed to a process for producing pearlite from an iron containing article comprising the steps of, (a) heating an iron containing article comprising at least 50 wt % iron for a time and at a temperature sufficient to convert at least a portion of said iron from a ferritic structure to an austenitic structure, (b) exposing said austenitic structure, for a time sufficient and at a temperature of about 727 to about 900° C., to a carbon supersaturated environment to diffuse carbon into said austenitic structure and (c) cooling said iron containing article to form a continuous pearlite structure.

Abstract: A precision weight (1) has greater permanence of mass due to a hardened surface layer that provides greater wear and scratch resistance as well as greater corrosion resistance. The hardened surface layer is a diffusion layer of increased carbon and/or nitrogen concentration resulting from a heat treatment under gas atmosphere.

Abstract: An iron-containing workpiece is case hardened by low temperature carburization during which one or more process steps—including adjusting the carburization temperature, adjusting the concentration of carburization specie in the carburization gas and reactivating the surfaces to be carburized—is carried out to enhance the overall rate and uniformity of carburization with minimized soot generation, whereby carburization can be completed faster than possible in the past.

Abstract: A high strength gear is provided which comprises a base metal of an iron-base alloy, the base metal being carburized or carbonitrided and having a tooth surface, and a coating containing Fe nitride and/or Fe carbonitride, formed on the tooth surface. A method of forming a high strength gear is also provided.

Abstract: A method for case hardening a chromium bearing nickel or ferrous based alloy, for example stainless steel, article, the method including the steps of activating the surface of the article; and carburizing the activated surface at a temperature below that temperature which would promote the formation of carbides. In one embodiment the surface is activated by disposing a layer of iron over the surface of the article.

Abstract: Steel alloys susceptible to case and core hardening comprise 0.05 to 0.24 weight percent carbon; 15 to 28 weight percent cobalt and 1.5 to 9.5 weight percent in nickel, small percentages of one or more additives: chromium, molybdenum, and vanadium; and the balance iron. Blades for ice skating or other sports equipment made from such alloys provide predictable and reproducible characteristics and permit fabrication with hardened edges on a ductile, strong substrate or base.

Abstract: A method is provided for heat treatment of metal workpieces obtain a substantially uniform nitride layer, even in workpieces comprising high alloy iron articles. The following method steps are provided: a) heating the workpieces to a temperature between 400° C. and 500° C. in a gas atmosphere comprising only ammonia; b) continuing to heat the workpieces to a temperature between 500° C. and 700° C. in a gas atmosphere containing ammonia and an added oxidizing agent; c) maintaining the workpieces at this temperature and in this gas atmosphere for a period of between 0.1 hour and 5 hours; d) continuing to maintain the workpieces at this temperature for a period of between 1 hour and 100 hours in a gas atmosphere containing ammonia or containing ammonia and a carbon-releasing substance; and, e) cooling the workpieces to room temperature.

Abstract: In a rolling bearing having a rolling bearing ring and a rolling element of at least 20 mm in diameter, at least one of the rolling bearing ring and the rolling element consists of carburized or carbonitrided steel containing at least 0.2 wt % and not more than 0.35 wt % of carbon and at least 2.2 wt % and not more than 3.6 wt % of Ni. Thus obtained is a rolling bearing capable of reducing the material cost and increasing the fatigue life or reducing the carburizing time by ensuring surface hardness and optimizing the case depth.

Abstract: An improved process for producing an atmosphere suitable for carburizing steel components by adding a small amount of oxygen to a mixture of natural gas and carbon dioxide, pre-heating the mixture to the desired reaction temperature in the presence of an inert material or a non-nickel-based catalyst that promotes the reaction between oxygen and natural gas without forming coke to avoid catalyst deactivation by coke formation, and reacting natural gas with carbon dioxide at high temperature in the presence of a catalyst.

Abstract: A carburizing method is described which is capable of dispersing cementite grains in the surface of steel uniformly and finely as not to affect fatigue strength and capable of fining the crystal grains of austenite. To prevent cementite precipitation during high temperature carburization at 980° C. or more, steel contains Al in an amount in the range of 0.05≦[Al wt %]≦2.0 and Cr in an amount in the range of 0.3≦[Cr wt %]≦4.0, and the composition of the steel satisfies the requirement represented by 1.9≧−5.6[Si wt %]−7.2[Al wt %]+1.1[Mn wt %]+2.1[Cr wt %]−0.9[Ni wt %]+1.1[Mo wt %]+0.6[W wt %]+4.3[V wt %].

Abstract: A ball-and-roller bearing is disclosed having an inner ring, an outer ring arranged on the axis of the inner ring and rotating around the co-axis relative to the inner ring, and a rolling body interposed between the inner ring and the outer ring and rolling with rotation of the outer ring relative to the inner ring. One of the inner ring, the outer ring, and the rolling body has a core member made from an alloy containing iron, at least one of 0.2 to 1.0% by weight of silicon and 0.2 to 1.5% by weight of manganese, 7.0 to 11.0% by weight of chromium, 1.5 to 6.0% by weight of molybdenum, and 0.5 to 8.0% by weight of cobalt, and a case hardened surface layer. Also disclosed is the method of manufacturing the bearing by forming a core member of the alloy, forming a case hardened layer containing 0.9 to 1.

Abstract: Austenitic stainless steel articles are treated to produce a hardened surface layer thereon by plasma heat-treating the articles at a temperature in the range of 300 to 600° C. and at a pressure in the range of 100 to 1500 Pa in a carbon-containing treatment atmosphere so as to introduce carbon interstitially into the austenite phase in a surface layer on the article.

Abstract: An improved vacuum carburizing method is provided which is easy to handle or to maintenance and low equipment costs without using hydrogen gas or acetylenic gas. The improved vacuum carburizing method comprises a carburizing treatment of workpieces made from steel material heated to about 900-1100° C. performed by introducing an ethylenee gas as a carburizing gas at a vacuum of 1-10 kPa in a carburizing furnace chamber.

Abstract: Rolling-element bearing components made from high quality steel are subjected to ion nitriding in a plasma as a final step in the manufacturing process to produce a layer with a hardness around 800-1200 HV with a depth no more than 150 &mgr;m. By controlling the conditions no friable surface layer is created and no further steps need to be performed on the component.

Abstract: The present invention provides a new and improved apparatus and method of carburizing ferrous metal parts. In one embodiment of the invention the apparatus comprises a radiant heater tube within which a source of hydrocarbon fuel is fully combusted, and a generator tube surrounding and forming a cavity around at least a portion of the radiant heater tube. The generator tube includes an input for air and enriching gas and an output to the process chamber of the furnace. The enriching gas is partially combusted or decomposed in the generator tube. This partially combusted gas is utilized to produce a carburizing gas for use in the process chamber of the furnace.

Abstract: A method for the heat treatment of steel, comprising carburization hardening said steel, to form carburized steel, followed by a second hardening, reduces the grain size of steel while precipitating carbonitrides inside the grains of steel, thereby increasing the strength of the heat-treated steel. The carburization hardening comprises heating the steel to a first austenitic temperature range in an atmosphere comprising a carburizing gas and optionally ammonia, cooling the steel to a martensitic temperature range, and quenching the steel, and the second hardening comprises heating the carburized steel to a second austenitic temperature range in an atmosphere comprising a carburizing gas and ammonia, and quenching the steel.

Abstract: A steel composition and method of processing have been developed that provide good grain coarsening resistance and optimum toughness after austenitizing at high temperatures for extended periods of time. The composition comprises, in % by weight, about: 0.10-0.40% C, 0.018-0.064% Nb, 0.024-0.066% Al, and 80-220 ppm N, the balance being Fe and other alloying elements found in common carburizing grades of steel. The steel is particularly suited to improving the core toughness of case-carburized components that require through-section toughness and fatigue resistance.

Abstract: The improved spherical plain bearing of the present invention is formed using a unique method of manufacture which includes surface hardening of the outer ring and the inner ring wherein the outer ring includes a fracture zone having a reduced cross-sectional area which allows the case hardening diffusion technique to penetrate much deeper into the ring fracture zone than in the other areas thereof. In this manner the reduced cross-section area of the outer ring provides a more brittle area with less of the more ductile interior steel which is more difficult to fracture. Such fracturing is necessary with such plain spherical bearings in order to allow placement of the inner ring within the outer ring. The spherical plain bearing produced by this method can include a single fracture or double fracture.

Abstract: A substantially carbon free (e.g. 50-80 ppm carbon max.) iron base melt is strip cast to provide a cast strip having a low strength, high ductility, essentially ferrite matrix substantially free of hardening acicular ferrite, bainite and martensite phases. The strip strength may be enhanced by subjecting the strip to a carburizing or nitriding treatment either directly after casting or after casting followed by cold rolling and annealing.

Abstract: Process for manufacturing a mechanical component made of steel, in which a blank of the steel component is manufactured and a high-temperature carburizing or carbonitriding treatment of at least part of the surface of the blank of the component is carried out, the chemical composition of the steel of which the component is composed comprises, by weight: 0.15%.ltoreq.C.ltoreq.0.35%; 0%.ltoreq.Si.ltoreq.0.6%; 0%.ltoreq.Mn+Cr+Ni+Mo.ltoreq.5%; 0%.ltoreq.Al.ltoreq.0.1%; 0%.ltoreq.Cu.ltoreq.0.5%; 0%.ltoreq.Ti.ltoreq.0.05%; 0.004%.ltoreq.N.ltoreq.0.02%; 0%.ltoreq.S.ltoreq.0.15%; P.ltoreq.0.03%; optionally, up to 0.02% tellurium, up to 0.04% selenium, up to 0.07% lead, up to 0.005% calcium, the balance being iron and impurities resulting from the smelting; the chemical composition being adjusted so that the Jominy curve of the steel is such that: 45 HRC.ltoreq.J.sub.3 .ltoreq.50 HRC; 39 HRC.ltoreq.J.sub.11 .ltoreq.47 HRC; 31 HRC.ltoreq.J.sub.25 .ltoreq.40 HRC; the average values J.sub.3m, J.sub.11m and J.sub.

Abstract: Monolithic metal oxide structures, and processes for making such structures, are disclosed. The structures are obtained by heating a metal-containing structure having a plurality of surfaces in close proximity to one another in an oxidative atmosphere at a temperature below the melting point of the metal while maintaining the close proximity of the metal surfaces. Exemplary structures of the invention include open-celled and closed-cell monolithic metal oxide structures comprising a plurality of adjacent bonded corrugated and/or flat layers, and metal oxide filters obtained from a plurality of metal filaments oxidized in close proximity to one another.

Abstract: A method for shot peening a hard metal product that has a hardened surface. The method includes projecting shot on the hardened surface of the hard metal product. The ratio of the Vickers hardness of the shot to that of the hardened surface is 0.8-1.6, and the diameter of the shot is 30-250.mu..

Abstract: A carburizing steel having the following chemical composition:C: 0.1 to 0.25%,Si: 0.2 to 0.4%,Mn: 0.3 to 0.9%,P: 0.02% or less,S: 0.001 to 0.15%,Cr: 0.5 to 0.9%,Mo: 0.15 to 1%,Al: 0.01 to 0.1%,B: 0.0005 to 0.009%,N: less than 0.006%, andthe balance of Fe and incidental impurities, wherein % is on a weight basis. Also disclosed are a method for the manufacture of the carburizing steel, parts of constant velocity universal joints for drive shafts made of the carburizing steel, as well as a method for the manufacture of such parts. The carburizing steel may further contain Ni: 0.3-4.0%, and one or more elements selected from the group consisting of Ti, Nb, V and Zr: 0.01-0.3% for each.

Abstract: A process for improving fatigue resistance of a case hardened component having a case thickness "t", subjected to one or more of rolling, sliding, abrasion, bending and pitting includes determining the magnitude of fatigue strength at surface and at a plurality of pre-selected points along thickness "t" of a component. The applied fatigue stresses acting upon the component at the surface and at the plurality of pre-selected points along thickness "t" are also determined. Then, a compressive residual stress profile is tailored from the surface to thickness "t" of the component. The compressive residual stresses at the surface and at the plurality of the pre-selected points along thickness "t" respectively have a magnitude sufficient to attain a net resultant stress which is at least 25% lower than the fatigue strength at the surface and the corresponding plurality of pre-selected points.

Abstract: The present invention provides a new and improved method of carburizing ferrous metal parts. In one embodiment the invention comprises the steps of heating the process chamber of a furnace to a temperature in excess of about 1100.degree. F., charging such parts to be carburized into the process chamber of the furnace, providing a carrier gas and feeding such carrier gas into the process chamber so as to provide a furnace atmosphere in the process chamber having a carbon potential of at least about 0.5%, providing a source of air and feeding such air to the process chamber so as to raise the carbon potential of the furnace atmosphere by at least 0.1%, and discharging the parts from the furnace. An enriching gas is fed into the process chamber along with the air. The enriching gas is a carbon (C) containing gas that may be decomposed to provide a source of free carbon (C).

Abstract: A method for treating soft magnetic parts by annealing and producing a wear guard layer, in which the soft magnetic parts are either successively annealed and provided with a wear guard layer in a reaction chamber of a treatment apparatus, or the annealing and production of a wear guard layer are done simultaneously in the reaction chamber. This avoids intermediate transportation and temporary storage as well as contamination of the parts and reduces the costs of the method. The method is especially suitable for treating soft magnetic parts of electromagnetic fuel injection valves.

Abstract: A powder metal gear wheel having a core density of at least 7.3 g/cc, and in one embodiment 7.4 to 7.6 g/cc and a hardened carburized surface. A method of manufacturing transmission gears comprises, sintering a powder metal blank to produce a core density of between 7.4 to 7.6 g/cc, rolling the surface of the gear blank to densify the surface, and then heating the rolled sintered part and carburizing in a vacuum furnace.