Abstract: A method for a surface treatment of a metal material, which comprises subjecting a metal material such as an Fe alloy, a Ni alloy and an Al alloy to a heat treatment in the presence of an amino-based resin such as a melamine-formaldehyde resin. The amino-based resin can be caused to be present with the metal material by a method wherein the resin is applied on the surface of the metal material, directly or via a solvent such as water, or wherein the amino-based resin is placed in a container, and the container and the metal material are placed in a heat treatment furnace. The above heat treatment allows a passivated film to disappear from the metal material. Further, a subsequent elevation of temperature and the supply a nitriding gas allows the performance of a nitriding treatment being several times more effective than a conventional treatment, and a subsequent supply of a carburizing agent allows the performance of a carburizing treatment.

Abstract: The disclosure provides a device and method used to produce a tubular structure made of a refractory metal compound. In particular, the disclosure provides a device and method used to produce a tubular structure made of a refractory metal compound by reacting a green tubular structure made of a refractory metal with at least one reactive gas.

Abstract: A method for processing a low manganese steel is more cost effective and improves residual stress, bending fatigue, and surface characteristics for driveline components. The low manganese steel comprises in combination, by weight, about 0.30-0.75% carbon (C) and 0.15-0.40% manganese (Mn), with the balance being essentially iron (Fe). The method for processing the low manganese steel includes carbonitriding the low manganese steel at temperatures between 1600° F. to 1750° F. for a time period of about three to six hours. The low manganese steel is subsequently quenched in a water based solution that is kept at room temperature. The process provides the low manganese steel with an irregular case profile with a core hardness of no more than 50 Rockwell C and a surface hardness of approximately 58-63 Rockwell C. Further, the process provides the low manganese steel with little or no intergranular oxidation or surface high temperature transformation product.

Abstract: A method for carbonitriding a steel part arranged in an enclosure maintained at a reduced internal pressure, the part being maintained at a temperature level, comprising an alternation of first and second steps, a carburizing gas being injected into the enclosure during the first steps only and a nitriding gas being injected into the enclosure only during at least part of at least two second steps.

Abstract: The invention relates to a method for carbonitriding at least one component (12) in a treatment chamber (16), in which at least one process gas (28; 30) is introduced into the treatment chamber (16), wherein a hydrogen content (44) is detected in an atmosphere developing in the treatment chamber (16) and is maintained in a desired range (55; 57) at least at intervals by influencing of the amount of the process gas (28; 30) that is fed.

Abstract: The present invention is directed to a method for protecting metal surfaces in oil & gas exploration and production, refinery and petrochemical process applications subject to solid particulate erosion at temperatures of up to 1000° C. The method includes the step of providing the metal surfaces in such applications with a hot erosion resistant cermet lining or insert, wherein the cermet lining or insert includes a) about 30 to about 95 vol % of a ceramic phase, and b) a metal binder phase, wherein the cermet lining or insert has a HEAT erosion resistance index of at least 5.0 and a K1C fracture toughness of at least 7.0 MPa-m1/2. The metal surfaces may also be provided with a hot erosion resistant cermet coating having a HEAT erosion resistance index of at least 5.0.

Abstract: Ferritic nitrocarburized surface treatment of cast iron brake rotors providing oxidation resistance, good braking performance and absence of distortion. Machined brake rotors are pre-heated, then immersed into a high temperature molten nitrocarburizing salt bath for a first predetermined dwell time. After removing the brake rotors from the nitrocarburizing salt bath, the brake rotors are directly immersed into an oxidizing salt bath at a lower temperature than the nitrocarburizing salt bath so that the brake rotors are thermally quenched. After a predetermined second dwell time in the oxidizing salt bath, the brake rotors are removed therefrom and further cooled to room temperature, either by water application thermal quenching or slow cooling in air. A fixture provides stable holding the brake rotors with a minimum of contact during placement in the salt baths.

Abstract: The present invention provides a gear, continuously variable transmission, constant velocity joint, hub, or other steel part superior in surface fatigue strength compared with the past and method of production of the same, that is, provides a carbonitrided induction hardened steel part made of steel comprised of a specific composition of chemical ingredients and carbonitrided, then treated by induction hardening, the steel part characterized in that a surface N concentration is 0.1 to 0.8 mass %, a sum of an N concentration and C concentration is 1.0 to 2.0 mass %, an amount of surface residual austenite is less than 15 vol %, a depth of the incompletely hardened layer from the surface is less than 5 ?m, and a surface X-ray diffraction half width is 6.0 degrees or more, and a method of production of the same.

Abstract: The present invention is directed to a method for protecting metal surfaces in oil & gas exploration and production, refinery and petrochemical process applications subject to solid particulate erosion at temperatures of up to 1000° C. The method includes the step of providing the metal surfaces in such applications with a hot erosion resistant cermet lining or insert, wherein the cermet lining or insert includes a) about 30 to about 95 vol % of a ceramic phase, and b) a metal binder phase, wherein the cermet lining or insert has a HEAT erosion resistance index of at least 5.0 and a K1C fracture toughness of at least 7.0 MPa-m1/2. The metal surfaces may also be provided with a hot erosion resistant cermet coating having a HEAT erosion resistance index of at least 5.0.

Abstract: The present invention is directed to a method for protecting metal surfaces in oil & gas exploration and production, refinery and petrochemical process applications subject to solid particulate erosion at temperatures of up to 1000° C. The method includes the step of providing the metal surfaces in such applications with a hot erosion resistant cermet lining or insert, wherein the cermet lining or insert includes a) about 30 to about 95 vol % of a ceramic phase, and b) a metal binder phase, wherein the cermet lining or insert has a HEAT erosion resistance index of at least 5.0 and a K1C fracture toughness of at least 7.0 MPa-m1/2. The metal surfaces may also be provided with a hot erosion resistant cermet coating having a HEAT erosion resistance index of at least 5.0.

Abstract: A method for carbonitriding a steel part arranged in an enclosure maintained at a reduced internal pressure, the part being maintained at a temperature level, comprising an alternation of first and second steps, a carburizing gas being injected into the enclosure during the first steps only and a nitriding gas being injected into the enclosure only during at least part of at least two second steps.

Abstract: The present invention relates to a component {1, 2, 3, 4, 6) within the interior of a vehicle. Specifically, the present invention relates to a part of a seat-structure. The present invention further relates to a process to produce a component { 1, 2, 3, 4, 6) Within the interior of a vehicle.

Abstract: Ferritic nitrocarburized surface treatment of cast iron brake rotors providing oxidation resistance, good braking performance and absence of distortion. Machined brake rotors are pre-heated, then immersed into a high temperature molten nitrocarburizing salt bath for a first predetermined dwell time. After removing the brake rotors from the nitrocarburizing salt bath, the brake rotors are directly immersed into an oxidizing salt bath at a lower temperature than the nitrocarburizing salt bath so that the brake rotors are thermally quenched. After a predetermined second dwell time in the oxidizing salt bath, the brake rotors are removed therefrom and further cooled to room temperature, either by water application thermal quenching or slow cooling in air. A fixture provides stable holding the brake rotors with a minimum of contact during placement in the salt baths.

Abstract: A method for improving surface mechanical properties of non-austenitic stainless steels comprises steps of: providing a non-austenitic stainless steel material; placing the non-austenitic stainless steel material in an environment containing at least one austenite-stabilizing element, and implanting the austenite-stabilizing elements into a surface of the non-austenitic stainless steel material to form a modified layer enriched with the austenite-stabilizing elements; and placing the non-austenitic stainless steel material in a carbon-bearing atmosphere to make the modified layer in contact with the carbon-bearing atmosphere, and maintaining the non-austenitic stainless steel material at a carburizing temperature below 600° C. to implant carbon into the modified layer to form a carburized layer.

Abstract: A gas injector including in which a gas is passed through high-voltage/low-current electrical discharges before being discharged into the chamber of a thermal treatment furnace. The electrical activation of the gas accelerates desirable reactions between the gas, gases in the furnace chamber, and the chamber workload. Preferably, a hot electrode is electrically charged and the other parts of the gas injector and the furnace are grounded. Also provided is a method for activating an atmosphere within the reaction chamber of a controlled-atmosphere reactor.

Abstract: A method for increasing wear resistance of a turbocharger includes exposing at least a bearing surface of a center housing of the turbocharger to a gas nitrocarburizing process or a plasma nitrocarburizing process, thereby forming a conversion coating impregnated onto the at least the bearing surface.

Abstract: The invention relates to a method and device for thermally treating workpieces, the device including a cooling chamber and two or more cementing chambers in which the workpieces are heated to a temperature of 950 to 1200° C. by means of direct heat radiation from a heating device.

Abstract: The disclosure concerns a method for treating a material in a static magnetic field having an intensity of more than 1 Tesla, including the following steps: a first step to heat the material, a second step to apply to the material a thermal shock and/or thermomechanical treatment and/or chemical treatment, wherein during at least the second treatment step, the material is subjected to the magnetic field while being held in position within the magnetic field.

Abstract: A process for duplex heat treatment of combined nitriding treatment and induction quenching treatment on an iron and steel material includes a chemical conversion treatment step for forming a chemical conversion film on a nitrogen compound layer formed on the iron and steel material by the nitriding treatment, after the nitriding treatment and before the induction quenching treatment. A compound layer formed on a surface of an iron and steel material by nitriding treatment is prevented from being oxidized by induction quenching, so that unevenness in film thickness between different portions of an oxidization-inhibiting film does not easily occur, with the result that a nitrogen-containing compound layer obtained after high-frequency heating remain uniformly.

Abstract: A method of activating an article of passive ferrous or non-ferrous metal by heating at least one compound containing nitrogen and carbon, wherein the article is treated with gaseous species derived from the compound. The activated article can be subsequently carburised, nitrided or nitrocarburised in shorter time at lower temperature and resulting superior mechanical properties compared with non-activated articles and even articles of stainless steel, nickel alloy, cobalt alloy or titanium based material can be carburised, nitrided or nitrocarburised.

Abstract: A carbonitriding method that can improve the nitrogen permeating rate to render the carbonitriding process effective is directed to carbonitriding a workpiece formed of steel that contains at least 0.8 mass % of carbon by heating in an atmosphere including ammonia, carbon monoxide, carbon dioxide and hydrogen. The method includes an atmosphere control step, and a heating pattern control step. The atmosphere control step includes an undecomposed NH3 partial pressure control step, a CO/CO2 partial pressure control step, and an H2 partial pressure control step. The undecomposed NH3 partial pressure control step, the CO/CO2 partial pressure control step and the H2 partial pressure control step are carried out such that the partial pressure of hydrogen in the heat treatment furnace is at least 0.1 atmospheric pressure and not more than 0.3 atmospheric pressure, and ? defined by the following equation (1) is at least 2.0 and not more than 6.0, in the atmosphere control step.

Abstract: A bearing part having long life against rolling contact fatigue, excellent in anti-crack strength and restricted in an increase of aged dimensional change, a heat treatment method thereof, and a rolling bearing including the bearing part are obtained. Steel for a bearing part is subjected to carbonitriding at a carbonitriding temperature exceeding the A1 transformation temperature, and cooled to a temperature lower than the A1 transformation temperature. The steel is reheated to a temperature for quenching that is not lower than the A1 transformation temperature but lower than the carbonitriding temperature, and then quenched.

Abstract: Steel for nitrocarburizing includes, by mass %, C: 0% to less than 0.15%; Si: 0.01% to 1.00%; Mn: 0.01% to 1.00%; S: 0.0001% to 0.050%; Al: 0.0001% to 0.050%; Ti: more than 0.50% to 1.50%; N: 0.0005% to 0.0100%; and the balance consisting of Fe and inevitable impurities, in which P is limited to 0.050% or less; O is limited to 0.0060% or less; and the amount of Ti [Ti %], the amount of C [C %], the amount of N [N %], and the amount of S [S %] satisfy 0.48<[Ti %]?47.9×([C %]/12+[N %]/14+[S %]/32)?1.20.

Abstract: An outer ring, an inner ring and a roller serving as a bearing component that adopts as a source material a steel ensuring a large fracture toughness value and also having an alloy element added thereto in a reduced amount and also provides sufficient wear resistance, are configured of a steel containing 0.15-0.3% by mass of carbon, 0.15-0.7% by mass of silicon, and 0.15-1.0% by mass of manganese, with a remainder of iron and an impurity, and have a raceway/rolling contact surface included in a region having a carbon enriched layer and a nitrogen enriched layer. In the nitrogen enriched layer the raceway/rolling contact surface has a nitrogen concentration equal to or larger than 0.3% by mass.

Abstract: A method for processing parts for kitchen tools in order to protect the parts from scratches, includes sequentially: a nitridation step, optionally including a nitrocarburizing step, between 592 and 750° C. in order to promote the formation of a nitrogen austenite layer; and a processing step for promoting the conversion of at least a portion of the nitrogen austenite into a phase with reinforced hardness.

Abstract: The invention relates to a method for producing a brake disc (BS) for a vehicle, comprising a main body (G) of a metal material, in particular gray cast iron, which has friction surfaces (R). The friction surfaces (R) are after-treated according to the invention by carboring, carbonitriding, case hardening, gas nitriding, oxide nitriding, gas nitro carburizing, plasma nitriding, plasma oxidizing, borating, plasma carborating or plasma borating.

Abstract: A carbonitrided part, where a base steel contains, in mass percent, C: 0.10 to 0.35%, Si: 0.15 to 1.0%, Mn: 0.30 to 1.0%, Cr: 0.40 to 2.0%, S?0.05%, and according to need further Mo?0.50%, with the balance being Fe and impurities, and in the region to a position of effective hardening depth from the surface of a hardened layer of the carbonitrided part, iron nitride particles of ?-Fe3N and/or ?-Fe2N are dispersed, and retained austenite is decomposed into bainitic ferrite, Fe3C, and ??-Fe16N2 has excellent abrasion strength and high pitting strength, although the base steel is a low-cost one with less content of Mo of an expensive alloy element or without addition of Mo. This carbonitrided part can be produced, for example, by subjecting the base steel part to carburizing in which the base steel part is held in a carburizing atmosphere at 900 to 950° C. and successively to carbonitriding in which the base steel part is held in a carbonitriding atmosphere with a nitrogen potential of 0.2 to 0.

Abstract: There is provided a bearing constituent member capable of achieving a long life of a rolling bearing and securing sufficient static loading capacity and dimensional stability and a production process thereof as well as a rolling bearing having a long life and exhibiting sufficient static loading capacity and dimensional stability. A workpiece obtained from a steel containing 3.2 to 5.0% by mass of Cr and 0.05% by mass or more to less than 0.5% by mass of V is subjected to a heat treatment such as a carbonitriding treatment. Thereby, the following are achieved: the content of C in the surface layer ranging from the surface of the bearing constituent member of the rolling bearing to 10 ?m is 1.1 to 1.6% by mass, Vickers hardness at the position of a depth of 50 ?m from the surface is 740 to 900 (Rockwell C hardness is 62 to 67), the ? amount at the position of a depth of 10 ?m from the surface is 20 to 55% by volume, particles composed of vanadium nitride having a particle diameter of 0.

Abstract: Obtain a bearing's component, a heat treatment method thereof, and a rolling bearing having a long life against rolling contact fatigue and high anti-crack strength, and suppressed long-term dimensional variation rate. The bearing's component is carbonitrided at a carbonitriding temperature higher than an A1 transformation point of steel for the bearing's component and then cooled to a temperature lower than the A1 transformation point, and subsequently, using a heat treatment apparatus that successively moves and heats each individual bearing's component, reheated to a range of quenching temperature of no less than the A1 transformation point and less than the carbonitriding temperature to be quenched.

Abstract: The present invention is directed to a method for protecting metal surfaces in oil & gas exploration and production, refinery and petrochemical process applications subject to solid particulate erosion at temperatures of up to 1000° C. The method includes the step of providing the metal surfaces in such applications with a hot erosion resistant cermet lining or insert, wherein the cermet lining or insert includes a) about 30 to about 95 vol % of a ceramic phase, and b) a metal binder phase, wherein the cermet lining or insert has a HEAT erosion resistance index of at least 5.0 and a K1C fracture toughness of at least 7.0 MPa-m1/2. The metal surfaces may also be provided with a hot erosion resistant cermet coating having a HEAT erosion resistance index of at least 5.0.

Abstract: The present invention relates to a method for manufacturing an implant, in particular an intraluminal endoprosthesis, having a body containing metallic material, preferably iron. For controlling the degradation of the implant the method includes the following steps: (a) providing a first part of the implant body; and (b) performing heat treatment which alters the carbon content and/or the boron content and/or the nitrogen content in the structure of a near-surface boundary layer in the first part of the implant body in such a way that strain on the lattice or a lattice transformation, optionally following a subsequent mechanical load, is achieved in the near-surface boundary layer. Such an implant is also described.

Abstract: A method for carbonitriding a steel part arranged in an enclosure maintained at a reduced internal pressure, the part being maintained at a temperature level, comprising an alternation of first and second steps, a carburizing gas being injected into the enclosure during the first steps only and a nitriding gas being injected into the enclosure only during at least part of at least two second steps.

Abstract: A treated austenitic steel and method for treating same includes an austenitic steel and a non-metal chemical element incorporated into a surface of the steel. The surface has a bi-layered structure of a compound layer at a top and an underlying diffusion layer, which protects said surface against hydrogen embrittlement.

Abstract: Thermo-mechanical properties of welds in stainless steel is substantially improved by the implementation of a post weld heat treatment that illiminates sigma phase in the heat treated zone and favors niobium carbonitride precipitate formation in a desirable size range. In most cases, post weld heat treated material can be employed in pressurized devices at temperatures exceeding 550° C., which is currently regarded the upper safe temperature limit, and material according to the inventive subject matter was tested at temperature of up to 850° C. without reheat cracking.

Abstract: An improved method for producing barrels which need to operate at temperatures exceeding 800 degrees for prolonged periods of time. The method described is ideally suited for barrels which are a part of a crew served weapons, belt feed systems or other fully automatic weapons. My method has limited effect on the accuracy potential of the barrel produced and therefore should not be excluded from use on shoulder fired weapons and precision rifles.

Abstract: A carbonitriding method that can improve the nitrogen permeating rate to render the carbonitriding process effective includes an atmosphere control step (50), and a heating pattern control step (60). The atmosphere control step (50) includes an undecomposed NH3 partial pressure control step (51), and a CO/CO2 partial pressure control step (53). The undecomposed NH3 partial pressure control step (51) and the CO/CO2 partial pressure control step (53) are carried out in the atmosphere control step (50) such that ac* defined by the following equation (1) is at least 0.88 and not more than 1.27, and ? defined by equation (2) is at least 0.012 and not more than 0.

Abstract: The invention provides a deep groove ball bearing which exhibits a long life even in a high-temperature environment or an environment involving the penetration of water in spite of its low alloying element content. The outer race, inner race and ball constituting the bearing are made of a steel which contains 0.3 to 0.4% of carbon, 0.3 to 0.7% of silicon, 0.3 to 0.8% of manganese, 0.5 to 1.2% of nickel, 1.6 to 2.5% of chromium, 0.1 to 0.7% of molybdenum and 0.2 to 0.4 of vanadium with the balance consisting of iron and impurities and in a total content of silicon and manganese of 1.0% or below, a total content of nickel and chromium of 2.3% or above and a total content of chromium, molybdenum and vanadium of 3.0% or below.

Abstract: The present invention provides a gear, continuously variable transmission, constant velocity joint, hub, or other steel part superior in surface fatigue strength compared with the past and method of production of the same, that is, provides a carbonitrided induction hardened steel part made of steel comprised of a specific composition of chemical ingredients and carbonitrided, then treated by induction hardening, the steel part characterized in that a surface N concentration is 0.1 to 0.8 mass %, a sum of an N concentration and C concentration is 1.0 to 2.0 mass %, an amount of surface residual austenite is less than 15 vol %, a depth of the incompletely hardened layer from the surface is less than 5 ?m, and a surface X-ray diffraction half width is 6.0 degrees or more, and a method of production of the same.

Abstract: Low temperature carburization of a workpiece surface is accomplished faster by impregnating the surface with a diffusion promoter prior to or during the low temperature carburization process.

Abstract: The present invention provides a valve lifter, including a buffer layer, a Me diamond-like carbon layer having a thickness of 0.3˜0.6 ?m, and a diamond-like carbon layer having a thickness of 1˜1.5 ?m and a SP3 bonding fraction of 60˜70%, which are sequentially formed on a base body which is subjected to carbonitriding treatment. The valve lifter can exhibit superior low-friction characteristics and wear resistance.

Abstract: A turbocharger includes a center housing having a bearing surface configured to contact an inner surface of a unison ring. A conversion coating is impregnated onto at least the bearing surface of the center housing.

Abstract: A ferrous metal tool is provided for the forming of light metal sheet workpieces at elevated temperatures, with the forming surface of the tool prepared to minimize friction and adhesion when engaged in deformation of the hot sheet metal. The forming surface of a steel tool is nitrocarburized to form a compound layer and diffusion layer on the surface. The compound layer initially comprises an outer gamma-phase material and an underlying epsilon phase material. Gamma-phase material is removed to expose underlying epsilon phase material, and low friction particles are embedded in the modified nitrocarburized compound layer of the forming tool.

Abstract: A method, and an article produced thereby, of providing a corroson-resistant, scratch-resistant, and stick-resistant, surface on a ferrous-metal-containing article, including forming microcavities in a ferrous-metal-containing article surface by ferritic nitrocarburization and seasoning the surface, including a non-stick agent deposited thereon. In preferred embodiments, the surface of the article including the exposed microcavities is oxidized before seasoning. The article includes cookware. Certain preferred embodiments include forming microcavities by ferritic nitrocarburization wherein the article is heated in an atmosphere including ammonia, nitrogen, and carbon-containing gas to a nitriding temperature of between about 800° F. and about 1300° F. for a time of about 0.5 hours to about 10 hours.

Abstract: Methods and apparatus are provided for plasma-assisted processing multiple work pieces in a manufacturing line. In one embodiment, the method can include placing the work pieces in movable carriers, moving the carriers on a conveyor into an irradiation zone, flowing a gas into the irradiation zone, igniting the gas in the irradiation zone to form a plasma (e.g., by subjecting the gas to electromagnetic radiation in the presence of a plasma catalyst), sustaining the plasma for a period of time sufficient to at least partially plasma process at least one of the work pieces in the irradiation zone, and advancing the conveyor to move the at least one plasma-processed work piece out of the irradiation zone. Various types of plasma catalysts are also provided.

Abstract: A carbonitriding method that allows the permeating rate of nitrogen to be increased to improve the efficiency of the carbonitriding process is directed to carbonitriding a workpiece formed of steel containing at least 0.8 mass % of carbon, including an atmosphere control step of controlling the atmosphere in a heat treatment furnace, and a heating pattern control step of controlling the temperature history applied to a workpiece. The atmosphere control step includes an undecomposed ammonia concentration control step of controlling the undecomposed ammonia concentration in the heat treatment furnace, and a partial pressure control step of controlling the partial pressure of at least one of carbon monoxide and carbon dioxide in the heat treatment furnace.

Abstract: The subject of this invention relates to method carburizing of steel products, mainly parts of machines, vehicles and every mechanical apparatus, in vacuum furnaces under reduced pressure and elevated temperature. The method of under-pressure carburizing of steel workpieces according to present invention relates to introduction of active nitrogen carrier during heating up of the load. Introduction of the active nitrogen carrier is terminated when the load reaches temperature required to start carburizing process; from this temperature the carbon carrier is added. Pressure in the furnace chamber during continuous or pulse introduction of the active nitrogen carrier should be maintained within the ranges from 1 to 500 mbar.

Abstract: A carbonitriding method that can improve the nitrogen permeating rate to render the carbonitriding process effective is directed to carbonitriding a workpiece formed of steel that contains at least 0.8 mass % of carbon by heating in an atmosphere including ammonia, carbon monoxide, carbon dioxide and hydrogen. The method includes an atmosphere control step (50), and a heating pattern control step (60). The atmosphere control step (50) includes an undecomposed NH3 partial pressure control step (51), a CO/CO2 partial pressure control step (53), and an H2 partial pressure control step (52). The undecomposed NH3 partial pressure control step (51), the CO/CO2 partial pressure control step (53) and the H2 partial pressure control step (52) are carried out such that the partial pressure of hydrogen in the heat treatment furnace is at least 0.1 atmospheric pressure and not more than 0.3 atmospheric pressure, and ? defined by the following equation (1) is at least 2.0 and not more than 6.

Abstract: A gas injector including in which a gas is passed through high-voltage/low-current electrical discharges before being discharged into the chamber of a thermal treatment furnace. The electrical activation of the gas accelerates desirable reactions between the gas, gases in the furnace chamber, and the chamber workload. Preferably, a hot electrode is electrically charged and the other parts of the gas injector and the furnace are grounded.

Abstract: A steel part according to the present invention is a part in which a surface of an austenitic stainless steel containing 3 to 20 mass % of Mn was carbonitrided to be hardened. By setting Vickers hardness of the surface to 1350 HV or more and setting a depth of a hardened layer having 1000 HV or more from the surface of the steel to 10 ?m or more, when the part according to the present invention is applied to a part required for sliding and wear resistance particularly, the service life can be improved significantly. Further, since the manufacturing method is performed by only heating in a gas atmosphere, a large number of parts can be simultaneously treated. Thus the stainless steel parts of the present invention can be adopted to wide fields as stainless steel parts required for wear resistance.

Abstract: The invention relates to case-hardening of a stainless steel article by means of gas including carbon and/or nitrogen, whereby carbon and/or nitrogen atoms diffuse through the surface into the article. The method includes activating the surface of the article, applying a top layer on the activated surface to prevent repassivation. The top layer includes metal which is catalytic to the decomposition of the gas.