Abstract: A method of carburizing ferrous metal parts that includes the steps of providing a furnace for heating the metal parts and a process chamber, purging the air atmosphere from the process chamber and heating said process chamber to a temperature of at least 1100° F., feeding a gas to the process chamber and a source of air at a constant flow rate to the process chamber, boosting the process chamber by feeding an enriching gas to the process chamber to create a carbon potential of at least 0.5%, and more preferably of at least 1.4%, cleaning the process chamber by decreasing the flow of enriching gas to the process chamber to create a carbon potential of less than about 0.25%, repeating the boosting step after performing said cleaning step, and repeating the cleaning step after performing said boosting step.

Abstract: A method for carburizing workpieces made of steel, particularly workpieces having outer and inner surfaces, the workpiece being held at a temperature in the range of 850 to 1050° C. in an atmosphere containing a gaseous hydrocarbon. At least two different gaseous hydrocarbons are used and/or the workpiece is alternatingly held in the atmosphere containing the gaseous hydrocarbon during a carburizing pulse and in an atmosphere free of hydrocarbon during a diffusion phase. Also described is a use of the method.

Abstract: The invention relates to a method of gas carburizing a metallic article, where at least the surface region of the article consists of an alloy with a chromium content of at least 10 wt %. The carburizing is carried out by means of a gas containing carbon, which gas is heated to a temperature below approximately 5500C. The gas is an un-saturated hydrocarbon gas.

Abstract: The invention relates to a method for generating an atmosphere for heat treating metal parts in a furnace, which includes inserting, in at least one phase of the treatment cycle or at least one area of the heat treatment furnace, a mixture comprising gaseous CO2 and ethanol in the form of fine droplets or vapor, so as to carry out the reaction between the CO2 and the ethanol inside the furnace to form a mixture of hydrogen and CO according to the reaction: CO2+C2H5OH?3 CO+3 H2, characterized in that the injection is performed in a phase of the treatment cycle or in an area of the heat treatment furnace in which the temperature is higher than 750° C., while CO2 alone or optionally mixed with nitrogen is injected in the phase or phases of the treatment cycle or in the area or areas of the furnace in which the temperature is lower than 750° C.

Abstract: A low-temperature stainless steel carburization method comprises steps: providing a stainless steel material; placing the stainless steel material in a halogen-free reducing environment and maintaining the stainless steel at a first temperature ranging 1,050 to 1,400° C.; and placing the stainless steel material in a carbon-bearing atmosphere and maintaining the stainless steel material at a second temperature lower than 600° C. to implant carbon atoms into the stainless steel material to form a carburized layer on the surface of the stainless steel material. A halide-bearing gas or solution is not to be applied to activate the passivation layer, so the fabrication cost would be reduced and the safety of carburization process would be enhanced. Besides, the environment can be prevented from halide pollution.

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 low-temperature stainless steel carburization method comprises steps: providing a stainless steel material; placing the stainless steel material in a halogen-free reducing environment and maintaining the stainless steel at a first temperature ranging 1,050 to 1,400° C.; and placing the stainless steel material in a carbon-bearing atmosphere and maintaining the stainless steel material at a second temperature lower than 600° C. to implant carbon atoms into the stainless steel material to form a carburized layer on the surface of the stainless steel material. A halide-bearing gas or solution is not to be applied to activate the passivation layer, so the fabrication cost would be reduced and the safety of carburization process would be enhanced. Besides, the environment can be prevented from halide pollution.

Abstract: A method for carburizing workpieces made of steel, particularly workpieces having outer and inner surfaces, the workpiece being held at a temperature in the range of 850 to 1050° C. in an atmosphere containing a gaseous hydrocarbon. At least two different gaseous hydrocarbons are used and/or the workpiece is alternatingly held in the atmosphere containing the gaseous hydrocarbon during a carburizing pulse and in an atmosphere free of hydrocarbon during a diffusion phase. Also described is a use of the method.

Abstract: The invention relates to a method for the heat treatment of workpieces in a heat treatment furnace, wherein the treatment atmosphere in the heat treatment furnace is circulated. According to the invention, a propellant is injected into the heat treatment furnace in such a manner that the treatment atmosphere is essentially circulated by the injected propellant.

Abstract: Low temperature carburization of stainless steel using acetylene as the carburizing specie is carried out under soft vacuum conditions in the presence of hydrogen or other companion gas. As a result, formation of soot and the undesirable thermal oxide film that normally occurs during low temperature carburization is eliminated virtually completely.

Abstract: The invention provides a carburization treatment method in which the carburization treatment is conducted under a condition where an atmosphere within the furnace is maintained at a high carbon potential which is slightly blow a carbon solid solubility. Preferably, the internal pressure within the furnace is kept at 0.1 to 101 kPa, the hydrocarbon gas is one, two or more than two kinds of gases selected from the group consisting of C3H8, C3H6, C4H10, C2H2, C2H4, C2H6 and CH4, while the oxidative gas is an air, an O2 gas, or CO2 gas.

Abstract: The invention relates to a method of gas carburizing a metallic article, where at least the surface region of the article consists of an alloy with a chromium content of at least 10 wt %. The carburizing is carried out by means of a gas containing carbon, which gas is heated to a temperature below approximately 5500C. The gas is an un-saturated hydrocarbon gas.

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: The subject of present invention relates to mixture for carburizing of steel products, mainly parts of machines, vehicles and every mechanical apparatus, used in vacuum furnaces. Present invention relates to mixture for under-pressure carburizing containing the carbon carrier comprising two unsaturated hydrocarbons, likely ethylene and acetylene, in volume ratio from 0.1 to 2.00. The carbon carrier can be further mixed with hydrogen or ammonia.

Abstract: A fuel injection valve for internal combustion engines, having a valve body and at least one injection opening embodied in it, through which opening, controlled by a valve needle that cooperates with a valve seat embodied in the valve body, fuel can be injected into the combustion chamber of the engine. The valve body comprises a high-alloy hot-work steel, which has been hardened by a case-hardening process.

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: The invention relates to a low-pressure carburising method comprising alternating low-pressure enrichment steps and diffusion steps in the presence of a neutral gas. During the enrichment steps, an enriching gas and neutral gas mixture is used, the proportion of the neutral gas being between 5 and 50% by volume of the enriching gas. The enriching gas can be, for example, acetylene (C2H2).

Abstract: Vacuum carburizing of ferrous workpieces is performed at low pressure in a vacuum furnace using an unsaturated aromatic such as benzene as the carburizing medium. The unsaturated aromatic is gas phase hydrogenated into a napthenes, such as cyclohexane, which is metered into the furnace chamber proper and functions as the carburizing gas. The furnace is constructed to be generally transparent to the napthenes so that cracking tends to occur at the workpiece which functions as a catalyst to minimize carbon deposits. The unsaturated aromatic is supplied in liquid form to fuel injectors which inject the liquid aromatic as a vapor at duty cycles and firing orders to produce a uniform dispersion of the hydrocarbon gas about the work resulting in uniform carburizing of the workpieces. An in-situ methane infrared sensor controls the process.

Abstract: Vacuum carburizing of ferrous workpieces is performed at low pressure in a vacuum furnace using a napthene hydrocarbon as the carburizing medium. The furnace is constructed to be generally transparent to the napthene so that cracking tends to occur at the workpiece which functions as a catalyst to minimize carbon deposits. The napthene is supplied in liquid form to fuel injectors which inject the liquid napthene as a vapor at duty cycles and firing orders to produce a uniform dispersion of the hydrocarbon gas about the work resulting in uniform carburizing of the workpieces. An in-situ methane infrared sensor controls the process. Hydrogen is added to the napthene to either assure full carbon potential and produce methane or to perform variable carburizing.

Abstract: A fuel injection valve for internal combustion engines, having a valve body (1) and at least one injection opening (11) embodied in it, through which opening, controlled by a valve needle (5) that cooperates with a valve seat (9) embodied in the valve body (1), fuel can be injected into the combustion chamber of the engine. The valve body (1) comprises a high-alloy hot-work steel, which has been hardened by a case-hardening process (FIG. 1).

Abstract: The invention relates to a low-pressure carburising method comprising alternating low-pressure enrichment steps and diffusion steps in the presence of a neutral gas. During the enrichment steps, an enriching gas and neutral gas mixture is used, the proportion of the neutral gas being between 5 and 50% by volume of the enriching gas. The enriching gas can be, for example, acetylene (C2H2).

Abstract: A process for heat treating metal workpieces, especially for the combined carburizing, boriding and hardening of ferrous products, contains with respect to an efficient process control the following successive operations following directly one after the other:

Abstract: Vacuum carburizing of ferrous workpieces is performed at low pressure in a vacuum furnace using a napthene hydrocarbon as the carburizing medium. The furnace is constructed to be generally transparent to the napthene so that cracking tends to occur at the workpiece which functions as a catalyst to minimize carbon deposits. The napthene is supplied in liquid form to fuel injectors which inject the liquid napthene as a vapor at duty cycles and firing orders to produce a uniform dispersion of the hydrocarbon gas about the work resulting in uniform carburizing of the workpieces. An in-situ methane infrared sensor controls the process. Hydrogen is added to the napthene to either assure full carbon potential and produce methane or to perform variable carburizing.

Abstract: A thin film of metal or metal compound is produced by preparing an ultrafine particle dispersion liquid by dispersing ultrafine particles at least partly made of metal into a given organic solvent, applying the ultrafine particle dispersion liquid to a substrate, drying the ultrafine particle dispersion liquid to leave metal or metal compound particles on the substrate, heating the metal or metal compound particles to join the metal or metal compound particles, and annealing the metal or metal compound particles into a thin film.

Abstract: Systems useful for superadiabatic combustion generation of a reducing atmosphere for metal heat treatment include a superadiabatic reactor which supplies a reducing atmosphere to a metal heat treatment apparatus. In one aspect, the reactor includes a porous medium and a start-up heater in the flow path of the gas that is to be heated. In another aspect, the gas is passed through a porous medium in alternating, opposite directions by the control of valves which lead the gas to and from the medium. In yet another aspect, a gas inflow pipe leads into an insulated porous bed from which the gas flows in a counter flow manner around the inflow pipe.

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: 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: In a method of and apparatus for controlling an atmosphere in a heat treatment furnace according to the present invention, a carburizing is carried out while supplying a hydrocarbon series gas and an oxidization gas into the furnace. The quantity of a residual CH.sub.4, a partial pressure of the oxidization gas and a partial pressure of CO are measured. The quantity of each gas to be supplied into the furnace is controlled according to either one of the values of the partial pressures.

Abstract: In a method of and apparatus for controlling an atmosphere in a heat treatment furnace according to the present invention, a carburizing is carried out while supplying a hydrocarbon series gas and an oxidization gas into the furnace, and the supply of the hydrocarbon series gas is stopped either when the quantity of a residual CH.sub.4 in the furnace is changed to increasing from decreasing, or when a partial pressure of oxygen in the furnace reaches a predetermined value.

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: In a cementation method of metals in which hydrocarbon gas and oxidization gas are introduced into a heat treatment furnace, a small quantity of hydrocarbon gas of is introduced at a low pressure into the heat treatment furnace. The shift time and the gradient of the carbon potential varying toward a predetermined high or low level are controlled by increasing or decreasing the quantity of cementation gas and oxidization gas to be supplied to the furnace. After the carbon potential is reached to the high or low level, the carbon potential is maintained for a predetermined time period so as to prevent the deposited carbide from being bulked. In order to prevent the gas supply pipe from being choked with the soot of the hydrocarbon, oxidization gas of intermediate pressure is flushed into the gas supply pipe.

Abstract: A method for controlling the CO contents of furnace atmosphere for carburizing and carbonitriding metallic workpieces in a furnace includes the step of directly feeding a mixture of an oxidizing reagent and a hydrocarbon-containing fuel into the furnace for producing a CO-containing furnace atmosphere. The CO contents of the furnace atmosphere is measured and compared to a preset minimal CO value. A CO-forming substance is introduced into the furnace atmosphere when the measured CO contents is no longer greater than the preset minimal CO value.

Abstract: In order to keep down soot production and to enable every part of the workpiece, including deep concavities to be uniformly carburized by vacuum carburizing, and to enable decreases in the quantities of gas and heat employed, carburizing treatment is performed in the heating chamber 2 of a vacuum carburizing furnace 1 with workpieces M being heated while acetylene gas is supplied from a carburizing gas source C inside the heating chamber 2, and the inside of the heating chamber 2 being evacuated by a vacuum evacuation source V to give a vacuum of .ltoreq.1 kPa.

Abstract: A treating material W pre-heated to a carburizing temperature of 750.degree.-950.degree. C. is heat-treated in a carburizing atmosphere directly supplied with hydrocarbon and oxidizing gases and heated to 1000.degree.-1100.degree. C. Then, the treating material W is forcibly cooled to a temperature below 600.degree. C., the treating material W is re-heated to 750.degree.-850.degree. C., and then it is hardened.Energy required to the carburization can be saved because drastic reduction of the treating time is possible.

Abstract: An exhaust gas of hydrocarbon is converted to an exothermic generated gas when it is burnt with air in a burner. The exothermic generated gas which has been dehydrated, is employed as a furnace atmosphere for decarburization or carburizing heat treatment, by the addition thereto of cracked methanol gas so that CO and H.sub.2 contents of the atmosphere gas may get near 1:1.

Abstract: Methods for preparing magnetic strips are provided in which the strips are manufactured to a thickness of less than about 0.005 inches and are made of a ferrous alloy having a carbon content of from about 0.4 to about 1.2 weight percent. The strips are prepared by first manufacturing an alloy having a carbon content below about 0.5 weight percent to the desired thickness and then subjecting the strip to a carburizing step to raise the carbon content in the strip.

Abstract: Workpieces of steel are hardened by carburizing the surface and then quenching. The carburizing is performed by means of a plasma discharge in a vacuum, in the presence of gaseous hydrocarbons at voltages between 200 and 2000 volts, preferably between 300 and 1000 volts, and preferably with the admixture of argon. The plasma is produced by means of electrodes operated in a vacuum, the cathode of which serves as workpiece holder and is operated by pulsed operation. In order to achieve a uniform hardness distribution and to reduce the mass flow of carbon, even in the case of irregularly shaped workpieces, the carburization is performed at a total pressure between 14 and 30 mbar, the pulse duration is selected between 110 and 10,000 .mu.sec, and the pause duration is selected between 30 and 10,000 .mu.sec.

Abstract: A variable gas generator is disclosed which is capable of producing a wide variety of product gas compositions heretofore produced only by either exothermic gas generators or endothermic gas generators or a combination of gas generators. The variable gas generator includes a nitrogen membrane module producing a nitrogen-oxygen feed gas which is combined with a hydrocarbon fuel and fed into a conventional endothermic gas generator. By controlling the nitrogen membrane module to produce a desired oxygen-nitrogen feed gas and by controlling the addition of methane and the catalyst bed temperature of the gas within the endothermic generator, a wide variety of product gas composition with carbon potential varying anywhere from one to 80% combustibles can be produced.

Abstract: A blackening treating furnace includes a soot generation burner for blowing an incomplete combustion flame toward a surface of a cold-rolled stainless steel strip moving continuously through the furnace. A pair of secondary air nozzles installed at positions enclosing the incomplete combustion flame blow secondary air toward the surface of the stainless steel strip in directions perpendicular thereto or in directions slightly inclined toward the middle of the incomplete combustion flame. A flame guide air nozzle is installed between the pair of secondary air nozzles and an exhaust duct for drawing and discharging the combustion reaction flame of the incomplete combustion flame and secondary air along the direction of movement of the stainless steel strip. The flame guide air nozzle injects flame guide air toward the combustion reaction flame in a direction perpendicular to the direction of movement of the stainless steel strip or in a direction inclined thereto.

Abstract: Steel is carburized at a temperature within the austenitic range and in an atmosphere which comprises nitrogen, hydrogen and carbon monoxide, by lowering the hydrogen concentration in the treatment atmosphere prior to cooling steel in oil, salt or water, so as to reduce the hydrogen concentration in the carburization layer of the steel, by outward diffusion of hydrogen from the carburization layer.

Abstract: A process and an installation for heat treatment or thermochemical treatment of steel permit instantaneous and permanent checking of the concentration of carbon at the surface of the steel, particularly in the course of the carbon enrichment of the surface zone of a workpiece. The process provides for the circulation in contact with this surface zone of a gaseous flux permitting the saturation concentration of carbon at the surface to be obtained at maximum speed, and for regulating this flux as a function of time. The installation comprises a monitored-atmosphere furnace having an input and an outlet for a gaseous flux, feed means forming this gaseous flux, and means for regulating the gaseous flux; it is equipped with data-storage and/or calculating means, and the feed means are designed to form a gaseous flux suitable for obtaining a saturation concentration of carbon at the surface of the workpieces in less than one minute.

Abstract: A gas-carburizing process wherein an article is treated by feeding a hydrocarbon gas and an oxidative gas of raw material gases directly into an atmospheric heat treating furnace, characterized in that, when the pressure within the furnace is negative, CO.sub.2 is fed as a negative pressure dissolving or eliminating means.A gas-carburizing apparatus wherein a gas inlet for feeding a hydrocarbon gas and an oxidative gas provided in the ceiling part of an atmospheric heat treating furnace is provided with a CO.sub.2 feeding part for eliminating the negative pressure within the furnace.