252 results about "Gas quenching" patented technology

The invention discloses a sintered neodymium-iron-boron preparation method capable of improving intrinsic coercivity and anticorrosive performance. On the basis of a double-alloy preparation process, Ce-enriched multicomponent rare-based alloy with high amorphous forming ability is used as an auxiliary alloy, and the decrystallizatoin of crystal boundary phase structure is realized by gas quenching cooling in a sintering tempering process. In the invention, the intrinsic coercivity is obviously improved, the anticorrosive weight loss is greatly reduced, the magnetic performance and anticorrosive performance are high, and the method can be widely used in the field of production of high-performance anticorrosive sintered neodymium-iron-boron material.

The present invention relates to a wrought, quenched and tempered, fine-grained, with deep hardenability, high strength and low alloy steel having a sum of the alloying elements: nickel, molybdenum, tungsten, vanadium, titanium, and niobium in weight percentage of 1.60% maximum in the first embodiment; vanadium, titanium, and niobium in weight percentage of 0.40% maximum in the second embodiment; titanium and niobium in weight percentage of 0.10% in the third embodiment. The air melted and hot forged steel of the first embodiment has hardness of HRC 55, an ultimate tensile strength of 300 ksi, a yield strength of 257 ksi, a total elongation of 9%, a reduction of area of 32%, and Charpy v-notch impact toughness energy of 15 ft-lb after normalizing, gas quenching, and tempering at 450° F.

The manufacture process of chain wheel for chain saw includes the following steps: powder metallurgy process to produce gear blank with sorted materials; precise forging through soaking graphite milk or coating graphite or setting in nitrogen protection, fast induction heating to 815-950 deg.c for less than 20 sec, fast forging in closed mold and demolding to reach gear density greater than 7.7 g / cu cm; assembling the gear to hub; and brazing and hardening in the protection of nitrogen with small amount of hydrogen inside a brazing furnace with fast cooling gas system for gas quenching to harden through phase change to reach hardness over HRC58. The manufacture process is simple, and has high production efficiency, low cost and high product precision and quality.

The invention discloses a system and a method for purifying tail gas of medical waste incineration. The method is characterized in that a spray gun is used for quickly cooling tail gas at 400-600 DEG C to below 200 DEG C in a tail gas quenching tower; the cooled tail gas enters into a semi-dry type reactor; lime and activated carbon are added in front of the semi-dry type reactor, so as to de-acidify the tail gas and absorb dioxin and heavy metal; dust is removed from the de-acidified tail gas by a bag-type dust collector; the de-dusted tail gas is subjected to spraying alkali wash through a spraying layer in a spraying absorbing tower; liquid drop carried by the tail gas after being subjected to the spraying alkali wash is removed by a demister in the spraying absorbing tower; and then the tail gas is heated after entering into a steam-tail gas heat exchanger, and lastly the tail gas is discharged from a chimney by a draught fan. By using the system and method provided by the invention, the purifying efficiency for the tail gas of medical waste incineration can be obviously increased. Especially, when a large amount of organic chloride is burnt, such as waste plastics (for example, PVC (polyvinyl chloride), PVDc (polyvinyl dichloride)), rubbers, leathers, and the like, concentration of HCL (hydrogen chloride) generated by being burnt is higher, the wet alkali wash is automatically performed, and the deacidification demand is still met, thereby reducing environmental pollution, generating no waste water and solving the problem of generating waste water by performing wet treatment.

The invention relates to a high-temperature synthesis gas sensible heat recovery device which is characterized by comprising a radiation boiler, wherein the radiation boiler is connected with a convection boiler by a synthesis gas pipe. The invention recovers the sensible heat of the high-temperature synthesis gas from an entrained flow gasifier by using a radiation type steam generator, a gas quenching step and a convection type steam generator to generate medium-pressure or high-pressure steam, thereby increasing the thermal efficiency for the gasification of the entrained flow by more than10-15%. The device is concise and compact, has reliable operation and low investment, is a high-efficiency and energy-saving device, and can be widely used in the fields of integral gasification combination cycle power generation (IGCC), methanol and alkene production, coal-to-liquid, spongy iron production by the synthesis gas direct reduction iron-making method and the like.

An apparatus for controlling NOx emissions which includes a chamber having a wall surface and an interior, a flue gas entrance and a flue gas exit for a flue gas to enter and exit the interior of the chamber, a gas quenching zone in which the temperature of the gas can be lowered, an ozone injection and retention zone in the chamber, and a liquid spray zone including at least one spray nozzle for spraying a liquid towards the wall surface.

The invention discloses a fixed bed Fischer-Tropsch synthesis reactor, which mainly comprises a reactor shell, a heat exchange element, a catalyst bed layer, a gas inlet guide pipe and a gas outlet guide pipe, wherein the bottom of the catalyst bed layer is provided with a lower plate, and an upper plate is arranged above the catalyst bed layer. The reactor is characterized in that: a free expansion space is reserved between the initially filled catalyst bed layer and the upper plate; and the reactor is provided with a hot oil circulating system, a light oil quenching system and a quenching gas quenching system which are used for adjusting and controlling the temperature of a reaction bed layer. The invention also discloses a Fischer-Tropsch synthesis method, which is carried out in the fixed bed reactor. By the equipment and the method, a reaction environment of enhancing heat transfer and mass transfer is formed in direct and indirect heat transfer modes, the problem of recycling reaction heat in the Fischer-Tropsch synthesis reaction is effectively solved, and the aim of improving fixed bed Fischer-Tropsch synthesis production capacity is fulfilled.

The invention relates to a low-cost high-performance rare-earth AB5 type hydrogen storage alloy and a preparation method thereof. The hydrogen storage alloy is shown as the following general formula: Ml(Ni1-x-y-wCoxMnyAlzMw)mNn, wherein x, y, z, w, m and n refer to molar ratios, and x is more than 0 and less than or equal to 0.1, y is more than 0 and less than or equal to 0.2, z is more than 0 and less than or equal to 0.2, w is more than or equal to 0 and less than or equal to 0.06, m is more than or equal to 4.8 and less than or equal to 5.5 and n is more than 0 and less than or equal to 0.1; Ml consists of La and at least one of the element group consisting of Ce, Pr, Nd, Sm, Gd, Dy, Mg, Ti and Zr, wherein La accounts for 30 to 90 weight percent and the La accounts for 10 to 30 weight percent of the alloy correspondingly; M is at least one of Cu, Fe, Si, Ge, Sn, Cr, Zn, B, V, W, Mo, Ta and Nb; and N is Ca and / or Y. The hydrogen storage alloy consists of a single phase or an Al-Mn-Ni-Co phase which does not exceed 2 weight percent and / or an RE-N-Ni precipitated phase. The alloy is prepared by adopting single-double roller rapid quenching or common casting technology, keeping the temperature at 1173-1273K for 4 to 12 hours for annealing treatment, and performing water, oil or gas quenching treatment. The alloy has high capacity and long service life; meanwhile, high-price Co in the alloy has low content, so the alloy has the advantage of low cost; and the recycling performance is good.

Versatile vacuum furnace (also having high internal pressure capability) designed for facilitating directed gas flow has a treating chamber including a long, low profile work zone configuration, and powerful gas recirculation equipment with unique structure supporting gas flow patterns that facilitate high velocity gas flow into and through the chamber. The furnace can be used for single or multiple step metal treatment processes. An entire multi step process, for example, carburizing, including gas quenching, is accomplished relatively quickly in a single self-contained chamber of the furnace.

The invention discloses a nozzle cooling vacuum gas-quenching furnace which can perform convection heating, wherein, a furnace body is axially parallel to the ground, and an automatic control system is adopted. The nozzle cooling vacuum gas-quenching furnace is characterized in that: a heating chamber has a square body structure, cooling air ducts and nozzles are arranged around the inner wall of the square heating chamber, the nozzles are perpendicular to the surface of a working zone, two longitudinal ends of the heating chamber are provided with return air inlets, open-close air door structures with parallelogrammic rods are adopted, respective door opening cylinders are arranged and move almost perpendicular to a heat insulation layer, a convection fan is arranged in the heating chamber, and metal bellowses are used as dynamic seals at the sealing positions where the cylinders are introduced into the furnace; in a control system, each executive component is provided with an electromagnetic element which is connected with a circuit of the control system, and the opening and closing of air doors, the starting and stopping of the convection fan, and heating and cooling processes during the operation are interlockingly controlled by the control system. The novel heating chamber structure realizes convection heating, improves heating rate and evenness, reduces heat loss and also improves cooling effect.

A vacuum furnace for heat treating and rapid gas quenching insitu a work piece at pressures up to 20 Bar and high gas velocities. The furnace comprises a single chamber having an inner portion including a plurality of graphite heating elements and graphite insulation, an outer portion and an access door. Further included are movable radiation baffle doors. In their closed position hot gases heat treat the work piece. In their open position the hot gases escape through the opening created onto chevron-shaped baffles in the outer portion which reflect radiation heat energy back into the inner portion and diffuse only convective heat energy into a heat exchanger and a variable speed drive recirculating fan. The recirculating fan directs the cooling gases through cooling nozzles onto the work piece to quench it to a pre-programmed temperature.

The invention discloses a method and device for realizing steel slag quenching and waste heat recovery by using water and carbon dioxide. The method comprises the following steps that carbon dioxide and water vapor are mixed; the mixed gas is blown into a fluidized bed heat exchanger through a blowing system, and enters a gas circulation pipeline through a waste heat boiler; a part of the gas is returned to the gas blowing system, and the rest of the gas is fed into an air distribution plate; the molten metallurgical steel slag is introduced into the fluidized bed heat exchanger for gas quenching, and steel slag particles are generated to be suspended under the action of airflow; high-temperature gas enters the waste heat boiler for heat exchange, and low-temperature gas is formed to entera gas circulation pipeline; when the temperature of the steel slag particles is below 800 DEG C, an exothermic reaction occurs; when the temperature of the high-temperature gas is 450 + / -5 DEG C, CO2is supplemented; when the temperature of the material is below 150 DEG C, the gas blowing system is closed; and the device comprises a steel slag chute, the fluidized bed heat exchanger and the gas blowing system. According to the method, the waste heat recycling efficiency of the steel slag is high, the stability of the steel slag is good, the occupied area is small, the treatment period is short, and the gas consumption is low.

The invention discloses a vertical vacuum high-pressure gas-quenching furnace with a rotatable material rest, which is a bottom charging type vacuum furnace with a vertical downward-acting door and comprises a control system taking an industrial control computer and a PLC as main parts. The vertical vacuum high-pressure gas-quenching furnace is characterized in that: an inner circle of the inner side of a lower furnace door is provided with a rotating platform support which is coaxially provided with a rotating disc and the material rest, the lower part of the rotating disc is coaxially provided with a big gear, a pinion which is eccentrically arranged on a rotating driving mechanism is engaged with the big gear circumferencially to drive the rotating disc to rotate further to ensure that the material rest bearing workpieces can rotate around a vertical central axis; the root of the material rest is provided with a thicker thermal insulating layer, a lower shielding thermal insulating layer of a heating chamber is of a ring shape, and a ring platform shaped clearance is reserved between the thicker thermal insulating layer and the lower shielding thermal insulating layer; the rotating disc, the thermal insulating layer and the material rest on the rotating disc, and the rotating driving mechanism lift along with a furnace door; the vacuum furnace is controlled by adopting a PLC technology, and various actions, the temperature in the furnace and the rotation of the material rest are controlled interlockingly. The equipment can ensure that workpieces at various positions are uniformly heated, and the performances such as vacuum, positive pressure, dynamic seal, heat preservation, cooling and so on, are better assured.

The invention relates to a highly corrosion resistant R-Fe-B magnet and a preparation method thereof. Surface of the magnet body is covered with fusible and corrosion resistant non-magnetic metal alloy with thickness equal to or more than 2 mum and penetration depth equal to or more than 2 mum into the body. The preparation method comprises the following steps: smelting steel ingot; crushing the steel ingot into particles; crushing the particles into powder; profiling into a cylindrical magnet; melting the alloy metal at ambient temperature of 550 DEG C and fully stirring; putting the cylindrical magnet in melt metal alloy solution during sintering for penetration of the metal alloy solution for 3h; removing the magnet from the metal alloy solution and putting the magnet in an enclosed inert gas air-cooled cooling box for gas quenching, and naturally cooling; sintering in a vacuum sintering furnace; and grinding an excircle and slicing. The magnet has strong corrosion resistance, magnet corrosion by residual liquor at air holes and needle holes is greatly reduced, and hidden trouble of inability to electroplate areas at the air holes and the needle holes by surface treatment process such as electroplating is maximally avoided.

The invention discloses a horizontal high-pressure gas quenching-tempering-nitridation vacuum multipurpose furnace and relates to the field of metal vacuum thermal treatment. The furnace comprises a vacuum furnace main body, a heating chamber, a wind cooling system, a vacuum unit, a gas supplying system and an electric control system. The heating chamber comprises heating elements, a cylinder, a front cover and a back cover. The front cover and the back cover are provided with wind guiding holes. An air cylinder drives movable doors to open and close the wind guiding holes so as to guarantee circular flowing of cooling gas during tempering and gas quenching and to guarantee a closed structure of the heating chamber during nitridation. The furnace overcomes the disadvantages caused by adoption of metal nitridation tanks adopted by nitridation furnaces at present, namely slow heating and cooling speeds, low atmosphere pressure, and the like. The furnace is provided with using conditions for high-pressure high-flow-rate quenching and tempering, is simple in structure and practical, and truly achieves the using requirements on vacuum multipurpose furnaces.

The invention discloses a metal workpiece double layer coating suitable for high temperature environment and a manufacturing method thereof. The manufacturing method of the metal workpiece double layer coating suitable for the high temperature environment includes the following steps of 1) pretreatment: degreasing the surface of a metal workpiece, sandblasting roughening and cleaning; 2) spraying:preheating the pretreated metal workpiece, adopting an atmospheric plasma spraying device for spraying, first spraying a ceramic inner layer on the surface of the metal workpiece, then heating and spraying a metal outer layer and then spraying a metal layer on the side of an obtained coating; 3) heat treatment: conducting vacuum heat treatment on the sprayed metal workpiece and conducting gas quenching. According to the manufacturing method, the metal layer is sprayed on the ceramic layer. On one hand, the high cost of ceramic precision machining is reduced; on the other hand, various corrosion-resistant or wear-resistant alloy materials can be applied. In addition, the melting point of metal is lower than that of the ceramic, and the mechanical properties of the coating can be changed bythe heat treatment process.

A large reactor for preparing acetylene and synthesis gas through partial oxidation of hydrocarbon comprises a mixing area, a reaction area and a quenching area. In the mixing area, a hydrocyclone and a lateral air intake grid are arranged, either hydrocarbon or oxygen passes through the hydrocarbon and the other passes through the lateral air intake grid, then the two gases are fully and evenly mixed in the mixing area, and the mixing degree of hydrocyclone and oxygen reaches 99.9%. In the reaction area, a nozzle plate and a nozzle arranged on the nozzle plate are arranged, and the gas mixture is sprayed into the reaction area through the nozzle for partial oxidation reaction. In the quenching area, an internal component is arranged to achieve cold-wall operation, a quenching nozzle is arranged on the outer wall of the internal component, the spray range of a quenching medium required by pyrolysis gas quenching is shortened, pyrolysis gas quenching effect is guaranteed, and the production capacity of the reactor reaches thirty thousand tons per year or more.

The invention discloses a high-temperature tail gas quenching reaction tower of a refuse combustion furnace. The high-temperature tail gas quenching reaction tower comprises a tower body, wherein an anticorrosion and fireproof layer is arranged on the inner wall of the tower body; a high-temperature tail gas inlet is formed on the top of the tower body, a tail gas outlet is formed on the lower part of the tower body and a dust discharging opening is formed at the bottom of the tower body; and at least one cooling water atomizer is inserted on the top and the middle-upper part in the tower body respectively. The temperature of high-temperature tail gas can be quickly reduced to 150 to 170 DEG C, so the problem that the generation of dioxin cannot be prevented in the prior art is solved; meanwhile, an effect of removing HCL, SO2 and other harmful substances by a subsequent cloth bag dust remover is enhanced, water drops are prevented from being attached to the surface of a cloth bag and the service life of the cloth bag is prolonged. The concentration of harmful substances at the inlet of a chimney is lower than 1 / 3 or 1 / 5 of a national specified value.

A step quenching method by high-pressure gas features that in the initial gas quenching stage, the high-pressure gas medium which has high hardenability is used for avoiding the conversion of austenite structure to wards ferrite, bainite, or pearlite structure, and when the temp of workpiece is higher than the conversion temp of martensite, the low-pressure gas medium is used for ensuring the uniform structure conversion, so decreasing the deformation caused by heat treating.

A continuous gas carburizing furnace includes a gas carburizing processing chamber (a preheating chamber 2, a heating chamber 3, a carburizing chamber 4, a diffusion chamber 5 and a temperature decrease chamber 6) in which a gas carburizing process is performed on a workpiece 50, an oil quenching chamber 8 in which oil quenching is performed on the workpiece 50, and a gas quenching chamber 7 in which gas quenching is performed on the workpiece 50. The gas carburizing processing chamber includes a temperature decrease chamber 6 in which the temperature of the workpiece heated by a gas carburizing process is lowered. The temperature decrease chamber 6, the gas quenching chamber 7 and the oil quenching chamber 8 are arranged in that order from the upstream side to the downstream side in the conveying direction of the workpiece 50, and are adjacent to each other.

The invention provides a quenching gas recycling system, which comprises a nitrogen cylinder, a gas storage tank 1, a gas storage tank 2, a quenching work chamber, a filter, a cooler, an air compressor, a gas pipe, a ball valve, a pressure regulating valve, a safety valve, a check valve, a drainage valve and the like. The system fundamentally solves the problem of large gas consumption in the gas quenching process, and improves resource utilization, reduces environmental pollution index, reduces cost, and meets automatic control requirements by recycling waste gas. The quenching gas recycling system and the quenching work chamber are rigorously designed, and can quickly and efficiently complete gas quenching and nitrogen recycling work.

The invention discloses a production process of a roll bar type gas quenching furnace. The production process is applicable to hardening and tempering of a track shoe. The production method comprises the following steps of: placing a workpiece onto a rack; starting a quick discharging motor after the workpiece moves to a photoelectric switch in a rear area of a heating furnace; transferring the workpiece from the furnace to a travel switch of a feeding roller table of a quenching tank; stopping to move to a specified position through a material shifting device; moving the workpiece to a conveying roller table of the quenching tank within the given time; stopping to start a cylinder and keep downward; lowering a conveying frame and the workpiece into the tank; compressing the workpiece with an upper pressure quenching head and a lower pressure quenching head; then starting an upper spraying pump and a lower spraying pump to spray and cool both surfaces of the workpiece; starting the cylinder and keeping upward after the operation is done; starting a conveying motor of the quenching tank after the cylinder is in place; conveying the workpiece onto a discharging roller table of the quenching tank; shifting the material; then returning into a tempering furnace; and finally cooling with the spraying pumps. By adopting the production process, the problem that the track shoe is seriously deformed in the conventional quenching process is greatly solved, small deformation and uniform hardness are realized, and the production efficiency and economic benefit are increased effectively.

The invention relates to a vacuum heat treatment technology, and discloses a three-chamber vacuum furnace for high-pressure gas quenching and isothermal salt bath quenching, and a use method. The three-chamber vacuum furnace comprises three parts, that is, a gas quenching chamber, a heating chamber and a salt bath chamber, wherein the gas quenching chamber, the heating chamber and the salt bath chamber are sequentially connected; and the gas quenching chamber is mainly used for carrying out carburizing treatment on a heating workpiece under a vacuum environment or an inert-gas-charged environment, the heating chamber is mainly used for carrying out heating or preheating on the workpiece, a temperature achieves 900 DEG C and above, and then the workpiece enters the salt bath chamber and issubjected to salt bath treatment. A three-chamber mechanism is arranged in a split manner, convenient to repair and maintain, and capable of meeting the needs of different heat treatment processes. Ahorizontal conveying-taking mechanism realizes stable (slow-fast-slow) action through a double-speed motor, and is high in starting-stopping speed and short in workpiece conveying time. The three-chamber vacuum furnace is capable of completing the many processes of vacuum isothermal salt bath quenching, vacuum high-pressure gas quenching, vacuum low-pressure carburizing and the like. The main functions of the three-chamber vacuum furnace are capable of realizing the high-pressure gas quenching and isothermal salt bath quenching.

The invention discloses a direct gas quenching unit for a mesh-belt continuous brazing furnace, which comprises a gas quenching chamber (1) and a high-pressure centrifugal fan (7), wherein the gas quenching chamber (1) is connected with a brazing furnace (9), and the high-pressure centrifugal fan (7) is driven by a variable-frequency motor (8). The invention is characterized in that the upper part of the gas quenching chamber (1) is provided with a gas injection chamber (2) and a rotatable and adjustable gas curtain (3); the gas injection chamber (2) is communicated with an air outlet of the high-pressure centrifugal fan (7) through an air inlet pipe (6), and the air inlet pipe (6) is provided with a branch pipe (11) communicated with a liquid ammonia decomposing furnace; the top of the gas quenching chamber (1) is provided with an air suction pipe (4); the air suction pipe (4) is communicated with an air inlet of the high-pressure centrifugal fan (7) through a filter (10) and cooler (5); and the air inlet pipe (6) can be provided with a hydrogen adsorption device (12). The gas quenching unit is directly used for quenching workpieces by using nitrogen and hydrogen, which are generated by the brazing auxiliary apparatus-liquid ammonia decomposing furnace and pressurized by the fan; and compared with the oil-quenched workpieces in the prior art, the workpieces which are directlyquenched by gas with the gas quenching unit have the advantages of no surface oxidation, reliable quality, high production efficiency and lower production cost, and the hardness can be adjusted and set according to needs.

The invention relates to a gas quenching method for improving the stability of steel slag and recycling physical heat of molten steel slag, and belongs to the technical field of environmental protection of metallurgical industry solid waste disposal, secondary resource reutilization and the like. According to the technical scheme, CO2 in a large amount of coal gas generated by iron and steel enterprises is used for carrying out gas quenching on the molten steel slag in a gas quenching chamber, high-quality iron-rich powder and tailing powder are obtained after levigating and magnetic separation are carried out, secondary resource iron-rich powder can be completely utilized in multiple ways, and tailings can be efficiently utilized as high-quality secondary resources. In the gas quenching process, the cold-state CO2 and the molten slag are subjected to rapid heat exchange, the physical heat of the molten slag is converted into the physical heat of the CO2, the waste heat is recycled through a heat exchange device, and the purified CO2 obtained after dust removal is recycled. According to the gas quenching method, the problems of reutilization of free active substances of the steel slag, physical heat recycling of the steel slag and the like can be comprehensively solved, the use problem of partial capture of CO2 in the coal gas is solved, and safe, efficient and environment-friendly quenching, sorting and reutilization processes of the steel slag can be realized.

The invention discloses a neodymium iron boron magnet sintering process. A molded neodymium iron boron magnet is placed in a sintering furnace, the temperature is raised to 750 DEG C to 850 DEG C through 150 min to 180 min after vacuumizing is carried out, and heat preservation is carried out for 20 min to 40 min; then the temperature is raised to 1,000 DEG C to 1,050 DEG C through 60 min to 70 min, and heat preservation is carried out for 10 min to 30 min; the temperature is raised to 1,050 DEG C to 1,100 DEG C through 0 min to 10 min, and heat preservation is carried out for 300 min to 350 min; and finally inert gas is introduced for cooling, and the sintered neodymium iron boron magnet is obtained. According to the neodymium iron boron magnet sintering process, step type heating pre-sintering is adopted, the temperature gradient of the outside and the center of the magnet becomes small, the performance of the sintered magnet is improved, and the yield of the sintered magnetic is increased. The manner of gas quenching and natural cooling is adopted, neodymium iron boron compact tempering is achieved through the temperature in a furnace, and the aim of saving energy is achieved. Meanwhile, inert gas convection is utilized in the temperature raising and heat preservation process, so that gas and volatile substances released in the sintering process are taken out by the inert gas in the vacuumizing process, and compact is protected against oxidization.

The present invention specifically provides a heat treatment process for improving a GH4145 alloy pipe. The heat treatment process is characterized in that: the technical process comprises: (1) adopting a vacuum gas quenching furnace to carry out sectional heating for the pipe along with the furnace, wherein the two-stage heating process comprises that: in the first stage heating process, heatingalong with the furnace to the temperature of 600 DEG C, holding the temperature for 15-20 minutes, and eliminating harmful gas impurities; in the second stage heating process, heating to the temperature of 970-1040 DEG C from the temperature of 600 DEG C, holding the temperature for 15-20 minutes, eliminating the residual stress force, and stabilizing the organization; (2) carrying out rapid cooling: wherein the cooling pressure is 4-6 bar, the cooling rate is more than 350 DEG C per minute before the temperature is reduced to 500 DEG C so as to avoid the precipitation of the gamma' strengthening phase; (3) obtaining the finished product. According to the present invention, the vickers hardness of the heat-treated pipe is less than or equal to 240; the cooling gas is nitrogen or argon.

The invention belongs to the field of nuclear fuel manufacturing, and particularly relates to a chromizing nitriding surface treatment technology for austenitic stainless steel, which comprises the following steps: burying a workpiece into a chromizing agent, filling the workpiece and the chromizing agent into a chromizing tank, putting the chromizing tank into a chromizing furnace for chromizing heat treatment, putting the workpiece into a high-pressure vacuum gas quenching furnace, and converting a chromizing layer into a chromizing and nitriding composite layer, wherein the chromizing agent comprises chromium powder, a filling agent and a catalyst, and chromizing heat treatment comprises chromizing powder pretreatment, loading and packaging and then heat treatment; the nitriding treatment comprises cleaning and drying a sample, the workpiece and a nitriding furnace, and then carrying out nitriding heat treatment on the nitriding furnace. By means of the formula of the chromizing agent, the hardening phenomenon is avoided, damage to the workpiece is not likely to be caused, the relation between the chromizing heat preservation time factor and the chromizing layer thickness is designed, the chromizing layer thickness is controlled, workpiece deformation is reduced, the solid solution nitriding technology can meet the nitriding requirement, and the adverse effect on the material performance in the powder chromizing process is eliminated.

Versatile vacuum furnace (also having high internal pressure capability) designed for facilitating directed gas flow has a treating chamber including a long, low profile work zone configuration, and powerful gas recirculation equipment with unique structure supporting gas flow patterns that facilitate high velocity gas flow into and through the chamber. The furnace can be used for single or multiple step metal treatment processes. An entire multi step process, for example, carburizing, including gas quenching, is accomplished relatively quickly in a single self-contained chamber of the furnace.

The invention discloses a vacuum high-pressure gas quenching furnace with a diversity channel. The high-pressure gas quenching furnace with the diversity channel comprises a furnace body, wherein a centrifugal vane wheel is arranged on the rear end of the furnace body. The invention provides the high-pressure gas quenching furnace with the diversity channel, which is ingenious in structure arrangement and reasonable in arrangement; a hot air flow firstly and completely passes through a whole heat exchanger and then enters the centrifugal vane wheel, so that a better heat exchange effect and aneffect on protecting the centrifugal vane wheel against being impacted by a high-temperature air flow are achieved; the opening and the closing of each cabin door of a heating area and each baffle plate of a heat exchanger cabin port are automatically controlled through a program, and a specific gas quenching and cooling channel way is combined and built, so that workpieces can be quenched quickly and uniformly, and workpiece deformation is reduced; compared with a traditional square-shaped heating area gas quenching furnace, the novel structure is provided with the diversity gas quenching channel, so that a more uniform quenching effect can be achieved on large-sized workpieces, and the deformation is reduced maximally; and during quenching, a cooling air flow is more uniform to distribute, a quenching gas flow is larger, and the quenching time is shorter.