Method of cyclic gas nitration of structural alloy steel parts

FIELD: metallurgy.

SUBSTANCE: method of cyclic gas nitration of structural alloy steel parts includes part heating in the furnace up to the temperature of 540-650 C, isothermal holding at the heating temperature, during which the saturating atmosphere replacement is performed cyclically in two stages in each cycle, and subsequent cooling together with the furnace in the ammonia-base atmosphere. The nanoscale copper film is prelimenary applied to the part surface, and the mentioned heating is conducted in the ammonia and carbon dioxide atmosphere at a volume ratio of these components 1:1. The first cycle stage of isothermal holding is carried out in saturating ammonia atmosphere in a mixture with water vapour at a ratio of volumes of mentioned components 1:1 and obtaining the copper oxide film on the part surface. The second step of the mentioned cycle is carried out in saturating ammonia atmosphere in the mixture with carbon dioxide at the ratio of mentioned gas volumes 1:1, and with the copper oxide recovery up to forming the pure copper on the part surface. In the invention particular case, the thickness of the applied nanoscale copper film is within the range of 150-200 nm.

EFFECT: increase of metal ceramics solid area thickness up to a specified value in the diffusion nitrided layer, obtained at the parts surface from structural alloyed steel without the nitriding process duration increase and without reducing its hardness.

2 cl, 1 tbl, 5 ex

 



 

Same patents:

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, particularly, to chemical-thermal processing, in particular to cyclic gas nitration of alloys steels with application of nanotechnologies, and can be used for production steel dies for hot forming to be used at high temperatures. Heating is performed in the temperature range of T=550-590C. Then, alternate feed of air and ammonia at air feed interval larger than that of ammonia in a cycle and with formation of water steam. Oxide films are produced at die surfaces and have electric charge to allow formation of the structure that consists of iron nitride nanoparticle ply and monolith play of cermet as oxycarbonitride. Then, curing is performed follows by cooling together with furnace. In particular cases, cycle interval makes 50 s at furnace volume making 0.5 l.

EFFECT: higher heat conductivity of die surface, deterioration and heat resistance.

2 cl, 1 tbl, 2 dwg, 6 ex

FIELD: metallurgy.

SUBSTANCE: steel article are preheated in air and held at 350C to 400C, nitride hardening in atmosphere of ammonia and exogas, oxidising and cooling. Saturation is carried out in atmosphere of ammonia and exogas at volume ratio of 1:1 to 1:4 at 570C to 630C with subsequent cooling in exogas or oil. Then, polishing is performed to final size of the article and oxidising in air at 300C to 400C for 1-6 hours while cooling is carried out in air.

EFFECT: higher rust resistance, reduces deformation, higher precision.

6 tbl, 6 dwg

FIELD: metallurgy.

SUBSTANCE: it is implemented heating of products up to saturation temperature 450-780C in ammonia atmosphere with following isolation in saturating gaseous medium. In the capacity of saturating medium at isolation there are used air and ammonia, which are fed separately. Isolation of products is implemented alternately in atmosphere, and then in the atmosphere of ammonia with formation on the surface of products of multilayer structure, consisting of alternating to each other layers made of oxide and nitride phases of iron and corresponding alloying elements.

EFFECT: there are received products with optimal combination of increased hardness and wear resistance, increasing of operation useful life of products, operating in heavy load conditions.

2 dwg, 1 tbl, 8 ex

FIELD: metallurgy.

SUBSTANCE: it is implemented heating of products up to specified saturation temperature in the range 500-600C and following isolation in saturating atmosphere for diffusion saturation of products' surface by nitrogen. Heating of products up to required saturation temperature is implemented in inert atmosphere. After heating it is implemented isolation in air atmosphere with formation on surface of details of area made of ferric oxides. Isolation in saturating atmosphere is implemented with receiving of diffusion layer in the form of nano-particles from nitrides of alloying elements and nitrogen in solid solution of alpha iron.

EFFECT: it is increased hardness and wear resistance of products ensured by receiving of evenly hardened layer without distortion with keeping of initial geometry.

2 dwg, 1 tbl, 4 ex

The invention relates to the field of engineering, namely the part that deals with the issues of heat strengthening, thermochemical and thermomechanical hardening hardening

The invention relates to mechanical engineering and can be used in the manufacture of steel machine parts and tools with surface hardening

FIELD: process engineering.

SUBSTANCE: invention relates to machining of parts from ferrous alloys containing at least 80 wt % of iron or from unalloyed steel for kitchenware for antiscore properties. Nitration or carbonitriding at 592-750C are conducted to facilitate the creation of nitrous austenite ply between nitride and diffusion plies, oxidation is made to facilitate the conversion of at least a portion of nitride austenite into the phase of higher hardness. The latter is nitride braunite or nitride martensite. Note here that higher hardness is a mid magnitude between nitride ply hardness and that of diffusion ply.

EFFECT: higher burnt-on, anti-abrasion and corrosion resistance properties, lower production costs.

18 cl, 3 dwg

FIELD: metallurgy.

SUBSTANCE: high-temperature internal nitration is made for 2 mm deep parts from ferrite steel containing up to 0.2 wt % of carbon, 12-25 wt % of chromium and 0.5-3 wt % of titanium. Nitration is performed at 1000-1200C in the medium of pure nitrogen for 1-4 hours with post cooling in air. Then, annealing is made at 500-900 in oxygen-free medium for 1-5 hours with cooling with furnace.

EFFECT: higher hardness and heat resistance, simplified nitration and heat treatment.

1 ex, 1 tbl

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, particularly, to chemical-thermal processing, in particular to cyclic gas nitration of alloys steels with application of nanotechnologies, and can be used for production steel dies for hot forming to be used at high temperatures. Heating is performed in the temperature range of T=550-590C. Then, alternate feed of air and ammonia at air feed interval larger than that of ammonia in a cycle and with formation of water steam. Oxide films are produced at die surfaces and have electric charge to allow formation of the structure that consists of iron nitride nanoparticle ply and monolith play of cermet as oxycarbonitride. Then, curing is performed follows by cooling together with furnace. In particular cases, cycle interval makes 50 s at furnace volume making 0.5 l.

EFFECT: higher heat conductivity of die surface, deterioration and heat resistance.

2 cl, 1 tbl, 2 dwg, 6 ex

FIELD: process engineering.

SUBSTANCE: invention relates to thermal-chemical processing and can be used for nitration of complex-shape part including closed cavities. Nitration of steel parts in gasostat in atmosphere of molecular nitrogen comprises pre-evacuation of gasostat chamber to 30-60 kPa, forcing nitrogen via absorber, increasing nitrogen pressure at the rate of 0.01-0.06 MPa to preset pressure and heating to 750-1100C at the rate of 1-40C/min. Said absorber cleans nitrogen of oxygen and carbon-containing impurities to their concentration not over 0.3 wt %. After nitration cooling is performed at nitrogen pressure whereat nitration is terminated to temperature in the range of 350C - ambient temperature. Thereafter pressure is decreased to barometric pressure. Nitration is performed using the device with chamber accommodating container composed by barrel and coaxial cover. Said barrel comprises top and bottom chambers divided by horizontal perforated baffle. Tube is secured to cover bottom to extend via barrel top part into bottom part whereat powder absorber is arranged. Side openings are arranged at tube-to-absorber contact zone for uniform gas transfer via absorber.

EFFECT: stable nitrogen content in nitrated layer and layer thickness.

3 cl, 2 dwg, 1 ex

FIELD: metallurgy.

SUBSTANCE: steel slab is heated, its composition including in wt %: Si - 0.8-7, acid-soluble Al - 0.01-0.065, C - 0.085 or less, N - 0.012 or less, Mn - 1.0 or less, S - equivalent to Seq. defined by equation "Seq.=[S]+0.406[Se]", where [S] is S content, [Se] is Se content of 0.015 or less, Fe and unavoidable impurities making the rest. Slab is subjected to hot rolling, annealing, cold rolling, decarburising annealing for primary recrystallisation, coat application for secondary recrystallisation. Between decarburising annealing and secondary recrystallisation, nitriding processing (step S7) is performed at final annealing. Final temperature of hot rolling (step S7) makes 950C or lower. Note here that sheet cooling is started 2 seconds after final rolling while coiling is made at 700C or lower. Rate of hot-rolled sheet strip heating to 800C-1000C in annealing (Step S3) makes 5C/s. Cooling rate in period from termination of final rolling to start of coiling makes 10C/s or higher.

EFFECT: higher density of magnetic flux.

9 cl, 3 dwg, 4 tbl

FIELD: metallurgy.

SUBSTANCE: during treatment outer surface of part is coated with protective copper-bearing layer with thickness from 0.01 mm to 0.1 mm, and diffusion saturation of inner surface is performed by nitridation to the depth not more than 0.35 mm.

EFFECT: simplifying nitridation method of long hollow steel part and improving accuracy of geometrical dimensions of nitrided part.

1 ex

FIELD: metallurgy.

SUBSTANCE: slab heating is performed to temperature of 1280C-1390C so that the substance acting as inhibitor can be converted to the state of solid solution. After that, slab is subject to hot rolling in order to obtain steel strip. Steel strip is subject to annealing for formation of primary inhibitor in steel strip. Then, steel strip is subject to cold rolling for one or more times. After that, steel strip is subject to annealing in order to implement decarbonisation and perform primary recrystallisation. Then, nitration of steel strip is performed in mixed medium consisting of gaseous hydrogen, nitrogen and ammonia in the position at which steel strip can be moved, for formation of secondary inhibitor in steel strip. After that, steel strip is subject to annealing so that secondary recrystallisation can be performed.

EFFECT: improving magnetic properties of slab with certain chemical composition.

9 cl, 8 tbl, 7 dwg, 4 ex

FIELD: personal use articles.

SUBSTANCE: invention relates to cutlery and/or serving utensils. To avoid scratches and improve the corrosion resistance cutlery and/or serving utensils are used which are made of ferritic steel with a surface layer formed by heat treatment with nitriding and subsequent cooling, and is essentially martensitic, provided that the surface hardness of the surface layer, as defined in accordance with the method of determining of Vickers hardness HV3 (DIN ISO EN 6507) is 80-250% more than the minimum core hardness, also measured as a Vickers hardness HV3. In addition, the surface layer has a higher elastic modulus than the core. The surface treatment is carried out preferably by nitriding and heat treatment.

EFFECT: prevention of scratches and improvement of corrosion resistance.

15 cl, 1 dwg

FIELD: metallurgy.

SUBSTANCE: parts are preliminary surface locally alloyed with nitride-forming elements. On surface of parts there is applied coating at laser heating to temperature T=690-710C and it is conditioned during 3-4 hours. Further, there is performed low-temperature nitriding at heating to temperature T=570-590C and conditioning during 6-8 hours in ammonia medium.

EFFECT: uniform on surface strengthened layer; reduced duration of steel parts nitriding; maintaining high hardness of layer.

1 tbl, 6 ex

FIELD: metallurgy.

SUBSTANCE: procedure for nitriding steel items in glow discharge consists in vacuum heating items corresponding to cathode in plasma of nitrogen of higher density. Plasma of nitrogen of higher density is formed in a near cathode area with a beam of electrons generated and accelerated with an auxiliary anode. Electrons emitted from an electron gun are directed to the anode and to the auxiliary anode generating electron gas flow facilitating collision of electrons with neutral particles and maintaining plasma existence. Velocity of electrons motion is controlled with the auxiliary anode connected to its own source of power.

EFFECT: intensified nitriding, increased contact durability and wear resistance of strengthened layer.

1 dwg, 1 ex

FIELD: metallurgy.

SUBSTANCE: layer-after-layer application of nickel-phosphoric layer applied by chemical deposition, of aluminium-chromium-phosphate binding substance layer, and layer of hard lubrication coating applied on layer of aluminium-chromium-phosphate binding substance. Layer of the aluminium-chromium-phosphate binding substance is applied by the steel item with nickel-phosphoric layer immersion in the solution with aluminium-chromium-phosphate binding substance, and holding for 1 minute, then heat treatment at 400-410C for 40-45 minutes and cooling of the steel item to room temperature are performed. Layer of the lard lubricating coating is applied from the suspension with the following composition, g/l: cadmium chloride - 10-30, zinc nitrate - 20-50, magnesium oxide - 12-36, caustic silver - 10-20, orthophosphoric acid - 200-280, nitric acid - 5-20, molybdenum disulfide - 200-250, and distilled water up to 1 l. Then heat treatment at 300C for 120 minutes is performed. The hard lubrication coating is applied by brush or by dipping.

EFFECT: increased wear resistance, improved tribological properties of the coating at friction assemblies operating at elevated temperatures and loads.

2 tbl

FIELD: metallurgy.

SUBSTANCE: method of surface hardening of metal articles includes application on the article surface of layer of liquid or gel-like electric conducting adhesive material, then layer of material powder containing alloying element, or these components mixture. Then the metal article is loaded in the container filled with coal powder, article heating by current passage using the said container and metal article as electrodes. In particular case of the invention implementation as adhesive material the material that during heating does not evolve products preventing diffusion of the alloying elements in the article surface.

EFFECT: hardening of surface of the metal article due to formation of the high strength alloyed layer.

2 cl, 2 dwg, 4 ex

FIELD: machine building.

SUBSTANCE: diamond galvanic tool with abrasion resistant coating contains casing with diamond grains secured on it using galvanic links, and abrasion resistant coating applied on the galvanic link by physical vapour deposition (PVD). The specified tool contains intermediate layer with thickness 0.5-3.0 mcm applied by chemical vapour deposition (CVD) and located between the galvanic link and abrasion resistant coating. Layer of the abrasion resistant coating has thickness 0.5-6.0 microns, and is made out of the material selected from group of Ti, Zr, Hf, Al nitrides, carbides or carbonitrides or their compounds. The intermediate layer is made out of the material selected from the group of Ti, Zr, Al carbides or carbonitrides or their compounds.

EFFECT: increased service life of the tool due to improved adhesion of the abrasion resistant coating with the work coating of the galvanic tool.

1 dwg

FIELD: machine building.

SUBSTANCE: building-up welding of the hard alloy layer on back surfaces of axial cutting tools using the method of electrospark alloying is performed, which comprises the creation of carbide titanium or tungsten layer, or titanium boride or tungsten with cobalt or nickel binder with the width 80-90 mcm. The sharpening of back surfaces of the tool is performed with the rough tolerance for processing 20-30 mcm and the roughness Ra 0.8 mcm and additionally using the method of finishing plasma hardening a diamond-like silicon oxicarbonitrite-based coating with the width 1.5-2 mcm and with the hardness 53-54 GPa is applied.

EFFECT: increase of tool resistance and service life.

1 tbl, 12 ex

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