Method of chemical heat treatment of part from alloyed steel

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, in particular to methods of the chemical heat treatment of metals and alloys, and can be used in mechanical engineering for surface hardening of parts of machines, including the parts used in friction pairs, and also in cutting tools and die tooling. The method of the chemical heat treatment of a part from alloyed steel includes the placement of the part into the working chamber, activation of the part surface before chemical heat treatment, supply into the chamber of a working saturating medium, heating of the part to the temperature of chemical heat treatment and conditioning at this temperature until the formation of the required thickness of the diffusive layer. Activation of part surface before chemical heat treatment is performed by means of ion-implanted processing of the surface of the part at the energy of ions from 25 to 30 keV, radiation dose from 1.6·1017 cm-2 to 2·1017 cm-2, radiation dose set speeds from 0.7·1015 s-1 up to 1·1015 s-1 and when using as implanted ions of the following elements: C, N or their combinations. In special cases of the invention implementation the chemical heat treatment of the part is performed by a ion-plasma method. The ion-plasma method is the ion-plasma nitriding, either ion-plasma cementation, or ion-plasma nitrocementation.

EFFECT: increase of productivity and improvement of the quality of the process of chemical heat treatment, and also increase of the wear resistance of the parts after it.

3 cl, 1 ex

 



 

Same patents:

FIELD: process engineering.

SUBSTANCE: invention relates to thermal and chemical-thermal processing and can be used in machine building, etc. Proposed process comprises nitride hardening followed by annealing. Nitride hardening is executed in vacuum chamber in gas mix of 15 wt % of nitrogen and 85 wt % of argon at 650-700°C by vacuum heating in high-density plasma with the effect of hollow cathode. Said high-density plasma is generated between the part and perforated shield made of titanium alloy. Then, vacuum diffusion annealing is performed in argon at 800-850°C.

EFFECT: higher hardness and contact wear-resistance at lower working pressure and decreased holding interval.

3 dwg, 1 ex

FIELD: process engineering.

SUBSTANCE: invention relates to plasma chemical-thermal treatment, particularly, to method of ion-plasma nitriding and can be used in machine building, engine production, metallurgy, etc. Argon-based gas-discharge plasma is preliminary initiated. After holding of nitrogen in argon-base initiated plasma it is fed into gas-discharge plasma to feed a negative shift potential to processed article at smooth variation to working magnitude and to perform the isothermal curing. Thereafter, argon-nitrogen mix is replaced with pure nitrogen to create the plasma flux containing the nitrogen ions, to up the shift negative potential and to perform the isothermal curing in nitrogen plasma.

EFFECT: nitride-hardened ply is formed at article surface with stable-equilibrium microstructure with no fragile surface structure, higher hardness, no warpage, accelerated nitriding (some 3-5 times).

6 cl, 2 tbl, 4 ex, 6 dwg

FIELD: process engineering.

SUBSTANCE: invention relates to machine building and may be used for surface hardening. Proposed process comprises forcing of ionised gas produced fed through electric discharge on to part surface. Note here that said local coating is made with the help of nozzle arranged 8-10 mm from part surface at the angle of 70-80 degrees thereto. Note here that ozonised air is used as said ionised gas. Said ozonised air is obtained with the help of corona discharge of 400 mcA created inside said nozzle. Said ozonised air is forced to part surface at 0.2 kgf/cm2 and room temperature. Said ozonised air is forced to part of titanium alloy for 3 hours, to part of high-speed alloys for 3.5 hours and to hard-alloy part for 4 hours.

EFFECT: simplified process, lower labor input and costs.

4 cl, 1 ex

FIELD: technological processes.

SUBSTANCE: invention relates to the field of machine building, in particular, to the method to produce a protective nanocomposite coating on the surface of the item from heat-resistant nickel alloy exposed to high temperatures and mechanical loads. The item and the vacuum chamber are cleaned in the medium of inert gas, ion etching is carried out, after which they perform ion-plasma cementation, additionally they perform ion etching of the item surface and apply the coating by the method of physical deposition from vapour phase. Ion-plasma cementation with subsequent ion etching is carried out in stages with number of stages N, besides N≥1, until saturation of the near-surface layer with carbon in the specified item for the depth of up to 50 mcm. Onto the surface of the item they apply at least one microlayer from nichrome and aluminium alloy with silicon, which consists of nanolayers of specified materials with thickness of 1-100 nm, and then they apply a microlayer from nanolayers of oxides of nichrome and aluminium alloy with silicon having thickness of 1-100 nm. In particular cases of invention realisation the total thickness of a microlayer from nichrome and aluminium alloy with silicon makes 2.3-3.0 mcm, at the same time the specified microlayer is applied by means of serial passage of the item in front of targets of magnetrons from the specified materials. The thickness of a microlayer from oxides of nichrome and aluminium alloy with silicon makes 0.5-1.5 mcm, at the same time the specified microlayer is applied by means of serial passage of the item in front of targets of magnetrons from the specified materials as oxygen is supplied into the chamber.

EFFECT: invention provides for increased durability and heat resistance of a nickel alloy under conditions of high-temperature oxidation and erosion impact.

3 cl, 1 tbl, 1 ex

FIELD: electricity.

SUBSTANCE: device for thermochemical treatment of parts in non-self-maintained glow discharge comprises vacuum chamber and substrate for placement of parts, power supply source connected by negative pole to the substrate and by positive pole to the chamber body, thermionic-emission electrode, the second power supply source connected by negative pole to thermionic-emission electrode and by its positive pole to the chamber body, hollow cylindrical electrode having inner diameter exceeding geometrical dimensions of the treated part, and thermionic-emission electrode placed coaxially to the cylindrical electrode. Device comprises additional hollow cylindrical electrode placed coaxially to the first one and forming electrostatic lens with the first electrode. Symmetry axis of hollow cylindrical electrodes is oriented under angle equal to maximum angle of ion flow incidence to the treated part surface. Thermionic-emission electrode is placed at focus of electrostatic lens.

EFFECT: improved fatigue range for parts and reduced energy costs for thermochemical treatment.

1 dwg

FIELD: machine building.

SUBSTANCE: products are cleaned in a vacuum chamber in the inert gas medium, with further execution of ionic etching, ion-plasma nitriding alternating with ionic etching and application of nanocomposite coating using the method of physical vapour deposition using magnetrons. The temperature of thin-walled and thick-walled parts of products is levelled during cleaning of products in the medium of inert gas, ionic etching, ion-plasma nitriding alternating with ionic etching and application of nanocomposite coating by placement of products so that the thin-walled part of one product to be located between thick-walled parts of other products. The named application of nanocomposite coating is performed by application of microlayer composed of nanolayers with the thickness 1-100 nm from the titanium and chromium and the subsequent application of microlayer of nanolayers 1-100 nm from titanium and chromium nitrides. In specific applications of the invention the titanium and chromium microlayer is applied with the thickness 0.3-0.8 mcm by consecutive passing of the product in front of magnetrons with targets from the named materials. The microlayer of titanium and chromium nitrides is applied with the thickness 2.5-3 mcm by consecutive passing of the product in front of magnetrons with titanium and chromium targets when feeding into the nitrogen chamber.

EFFECT: increase of coating service life in conditions of erosion, corrosion and high temperatures.

3 cl, 1 tbl, 1 ex

FIELD: machine building.

SUBSTANCE: method of nitriding of the steel part in plasma of the glow discharge includes the steel part and perforated screen location in the vacuum chamber, cathode spraying, vacuum heating of the part in plasma of the glow discharge containing mixture of nitrogen-containing and inert gases creating areas with different steel structure; at that the transient area between the areas with different structure has microheterogeneous structure with gradual change of one type to the another one. The heterogeneous structure is formed in form of the macroheterogeneous steel structure using the perforated screen with holes diameter d, at that d > 4 l, where l is thickness of cathode layer, and closely fitting to the treated part to ensure the possibility to obtain on the surface areas nitrided in the glow discharge and alternating with unnitrided areas.

EFFECT: improvement of contact durability and wear resistance of the strengthened layer due to local treatment and creation of macroheterogeneous material structure.

4 dwg, 1 ex

FIELD: machine building.

SUBSTANCE: method of nitriding of the steel part in plasma of the glow discharge includes the steel part and perforated screen location in the vacuum chamber, cathode spraying, vacuum heating of the part in plasma of the glow discharge containing mixture of nitrogen-containing and inert gases creating areas with different steel structure; at that the transient area between the areas with different structure has microheterogeneous structure with gradual change of one type to the another one. The heterogeneous structure is formed in form of the macroheterogeneous steel structure using the perforated screen with holes diameter d, at that 2 l < d < 4 l, where l is thickness of cathode layer, and closely fitting to the treated part to ensure the possibility to obtain on the surface of areas nitrided in the glow discharge that alternate with unnitrided areas.

EFFECT: improvement of contact durability and wear resistance of the strengthened layer due to local treatment and creation of macroheterogeneous material structure.

5 dwg, 1 ex

FIELD: machine building.

SUBSTANCE: method of steel part nitriding in plasma of glow discharge includes the cathode spraying, vacuum heating in plasma of the glow discharge comprising of mixture of nitrogen-containing and inert gases with creation of areas with different steel structure. The transition area between areas with different structures has a microheterogeneous structure with gradual transition from one type into another. The heterogeneous structure is formed in form of the macroheterogeneous steel structure using the perforated screen with holes diameter d, at that d > 4 l, where l is thickness of cathode layer, and closely fitting to the treated part, and the screen to ensure effect of the hollow cathode closely fitting to the perforated screen to ensure the possibility to obtain on the surface areas nitrided in the glow discharge and alternating with unnitrided areas.

EFFECT: improvement of contact durability and wear resistance of the strengthened layer due to local treatment and creation of macroheterogeneous material structure.

4 dwg, 1 ex

FIELD: process engineering.

SUBSTANCE: invention relates to machine building, particularly, to ion-nitration of machine parts with the help of electromagnetic field pulses. Reaction gas is fed into nitration chamber and heated therein with simultaneous generation of alternating electromagnetic field therein by solenoid. Said solenoid houses processed part with direction of magnetic induction vector perpendicular to part processed surface and with variation nitration amount with formation of square pulses. Duration and cycle of said pulses ensure acceleration of nitrogen ions penetration in processed surface owing to vertical front of magnetic field intensity ride. Device to this end comprises part nitration chamber, reaction gas feeder, heater and electromagnetic field generator. The latter is composed of solenoid surrounding said chamber to generate pulsed electromagnetic field with square pulses and direction of magnetic induction vector perpendicular to part processed surface.

EFFECT: simultaneous acceleration of nitration, higher mechanical properties of surface plies.

4 cl, 3 dwg

FIELD: process engineering.

SUBSTANCE: invention relates to thermal processing of parts from alloyed cast iron with different graphite structure. This process comprises control over initial structure, thermal processing, nitride hardening and machining. Note here that the part initial structure content of graphite, cementite and ferrite is controlled. Thermal processing of parts from cast iron with structure including ball-shape graphite, that of other-than-ball-shape graphite in amount of 10% and ferrite in amount of up to 20% in executed by high tempering and aging while at the content of 10-80% of other-than-ball-shape graphite and 20-85% of ferrite austenitising is performed. Cooling is conducted at the rate of 5-15°C/s to temperature of upper beinite, isothermal tempering, high tempering and ageing. At content of 10-80% of other-than-ball-shape graphite and 20-85% of ferrite and up to 80% of cementite preliminary diffusion annealing, austenising and cooling at the rate of 5-15°C/s to temperature of upper beinite, isothermal tempering, high tempering and ageing are carried out. After thermal processing parts structure is controlled, part surface if machined with allowance for further machining to allow the removal of ε-phase ply after nitride hardening. Thereafter, parts sections with the least wall thickness are subjected to strain cold working. Now, the parts are phosphatised, subjected to low-temperature nitride hardening while part working surface is subjected to electrochemical etching, honing and phosphatising.

EFFECT: decreased deformation at nitride hardening.

7 cl, 1 ex

FIELD: machine building.

SUBSTANCE: invention relates to machine building, in particular, to the methods for the improvement of mechanic properties of near-surface layers of machine parts from iron-base alloys with obtaining submicro- or nanostructured state of diffused layers. The method involves assembling a package of alternating steel plates with different chemical composition, vacuumisation and heating of the package, hot deformation of the package in height under the temperature whose value falls between the temperature values of polymorphous transformation of both alloys, after the hot deformation the workpieces of parts are cut out of the package so that the direction of interlayer borders in the part workpiece coincides with the direction of the nitrogen diffusion flux during nitriding that follows, then nitriding is carried out to obtain submicro- and nanostructured state of diffused near-surface layer on the part surface.

EFFECT: method allows for the improvement of mechanical properties of material's near-surface layers formed in the course of nitriding and, respectively, longer service life of parts.

9 dwg, 1 ex

FIELD: electricity.

SUBSTANCE: plant contains vacuum chamber 1 with component holder 12 with insulated current lead and at least one long electrode 2 of arc plasma source; device for components heating and power supply units for vacuum-arc discharge 3 and component heating device 11. Component heating device 11 is an additional emission chamber 7 insulated by screens and insulators; inside this chamber there is long cathode 8 of vacuum-arc discharge which is electron emitter; emission chamber 7 is connected with vacuum chamber 1 by perforated partition 9 at that perforated holes 10 are located along longitudinal cathode axis 8 of vacuum-arc discharge. At that power supply unit 11 for component heating device has an option of connection to negative pole of emission chamber while positive pole is connected to component holder 12 or electrode 2. Power supply unit 3 of vacuum-arc discharge has an option of connection to negative pole of cathode 8 of vacuum-arc discharge or electrode 2, while positive pole can be connected to emission chamber 7 or vacuum chamber 1.

EFFECT: increase in uniformity of components heating.

2 cl, 1 dwg

FIELD: metallurgy.

SUBSTANCE: invention concerns methods of strengthening and modification of surface and can be used for endurance increasing of details made from titanium alloys, operating in corrosion-active mediums with presence of abrasive particle and high speeds of aggressive solution stream. It is implemented electrospark alloy addition of surface layer and following oxidation or nitriding. Electrospark alloy addition is implemented by nitride-forming elements or alloys on it basis. Then it is implemented thermal oxidation in oxidising air quality at the temperature 600-800°C during 2-16 hours or diffusive nitriding, which is implemented in catalystically prepared gas ammoniac environment at the temperature 500-680°C during 15-40 hours. In the capacity of nitride-forming alloys there are used ligature VCMA.

EFFECT: increasing of resistance against corrosion-erosion effect of corrosive mediums for products made of titanium alloys.

2 cl, 1 tbl, 1 ex

FIELD: metallurgy.

SUBSTANCE: invention refers to production of items out of pseudo-α or (α+β) titanium alloys, designed for continuous operation in friction pairs with polymer or metallic materials and biological tissues. First a stock is produced, then it is subject to thermo hydrogen treatment by means of saturation with hydrogen by thermo diffusion method till concentration of hydrogen reaches 0.5-0.9% in weight at temperature of 700-850°C. Then holding is carried out with successive cooling to an ambient temperature at the rate 0.1-10 deg/sec. Further there is performed firing in vacuum at not less, than 5-10-5 of mercury column at temperature of 550-700°C with holding within 4-20 hrs till concentration of hydrogen reaches not more, than 0.01 wt %. Polishing is carried out till obtaining of surface roughness parameter of Ra from 0.02 to 0.08 mcm. Then vacuum ion-plasma nitriding is executed at temperature of 300-700°C, till the thickness of nitrated layer is not less, than 50 mcm. With above described method there is produced an item containing nitrated surface layer consisting of nitrides of titanium of composition from Ti2N to TiN and sub-layer out of solid solution of nitrogen in titanium and a core.

EFFECT: creation of complex process facilitating high wear resistance and low friction ratio, also high corrosion resistance of items in corrosive, including biological, mediums.

17 cl, 2 dwg, 3 ex

FIELD: processes for heat treatment of cast iron parts with spheroidal graphite.

SUBSTANCE: method comprises steps of testing initial structure by means of coercive force meter and selecting heat treatment modes on base of testing results. Parts are subjected to austenization at 880 - 930°C; interim cooling of parts in furnace till temperature in range Ar3 - Ar1 ; cooling at rate 5 -10°C per minute till temperature in range between temperature of starting A - P conversion and temperature exceeding by 50°C maximum-stability of temperature of austenite being converted to upper bainite or troostite. Then part is subjected to isothermal soaking at such temperature till maximally possible degree of A - P conversion. After cooling structure is inspected by means of coercive force meter for detecting tendency of pearlite and tempered bainite to changes at further nitriding. Depending upon inspection results tempering mode is selected and after such tempering final testing of structure by means of coercive force meter is realized according to index values of scale developed on base of investigating relationship of readings of coercive force meter from initial structure and its changes at nitriding process and also from growth and warping of parts at nitriding.

EFFECT: possibility for producing stable structure resistant against changes at nitriding process.

2 cl, 1 ex

FIELD: metallurgy, namely thermal-chemical working, possibly for surface hardening of tools and machine parts.

SUBSTANCE: method comprises steps of preliminarily working and boronizing. Preliminary working is performed by means of electron beam in vacuum (P=2 x 10-3Pa) for 30 s at specific power ( 4 - 5) x 104 Wt/cm2. Boronizing is realized at temperature 940°C for 3 h in container having melting lock and filled with saturating mixture containing 97% of B4C and 3% of KBF4.

EFFECT: boronizing process providing surface hardening of tools, lowered brittleness of boride layer with increased thickness, reduced stresses in boride zone.

1 tbl, 2 ex

FIELD: protective coatings.

SUBSTANCE: invention can be used to form alloying coating by means of plasma treatment of materials. Formation of alloying coating comprises employment of arc discharge whose column is displaced in contact with surface being treated in interaction with alloying component-containing powder placed thereon. Cross-section area of arc column in contact zone is now increased by blowing column along all its length with highly turbulent gas flow. In this case, powder containing alloying component is fixed by a layer on the surface being treated, for which purpose powder is preliminarily mixed with a viscous material to form homogenous paste. Such viscous binder is selected from substances having adhesion to the surface in question and which are either inert for material of this surface or bear alloying component.

EFFECT: increased area of working zone of arc discharge on surface being treated and reduced intensity of energetic action resulting in increased uniformity and improved quality of the surface.

3 cl, 2 cl

FIELD: metallurgy; thermal and chemical thermal treatment of parts made from magnetically soft high-chromium steel.

SUBSTANCE: proposed method includes machining of parts followed by stabilizing annealing; in the course of annealing, carbo-nitriding is performed in charcoal mixtures with activating nitrogen- and carbon-containing additives at stepped heating first at temperature above Curie point 780-820 C continued for 3-4 h and then at temperature above Curie point 680-700 C continued for 2-3 h followed by cooling in container at rate of 50-80 C/h. Sometimes, abrasive jet treatment may be used instead of machining.

EFFECT: enhanced wear resistance of valve pair parts; increased service life of valves at retained corrosion resistance.

2 cl, 5 dwg, 1 tbl, 3 ex

FIELD: metallurgy, namely chemical and heat treatment of metals and alloys, namely ion nitriding in plasma of glow discharge, machine engineering, namely surface hardening of machine parts, possibly of complex-configuration parts, cutting tools and die fitting.

SUBSTANCE: at cleaning treated part in mode of cathode sputtering, pulse duration of negative voltage applied to article is discretely and successively increased by two steps at constant pulse repetition frequency. At first step pulse has width 18 - 20 ms sufficient for achieving article temperature 45 - 50°C. At second step pulse width is in range 38 - 40 ms for achieving article temperature 140 - 150°C. Then at heating in glow discharge for achieving saturation temperature, pulse width is in range 75 - 80 ms and it is sustained in such range during the whole process of saturation.

EFFECT: intensified cleaning process, enhanced quality of parts, especially of complex-configuration parts due to minimum arc generation at initial stage of cleaning process in mode of cathode sputtering.

1 tbl, 1 ex

FIELD: process engineering.

SUBSTANCE: invention relates to machine building and can be used for surface hardening of parts with threaded surfaces used, for example, in roller-screw and boll-screw gearings. This process comprises shaping the thread geometry by thread cutting tool and processing by electrolyte-plasma process. Here, part is dipped in electrolyte, 3-8% water solution of ammonia sulphate, to produce vapour-gas shell. Electric discharge is fired between processed part and electrolyte by feed of electric potential to processed part. Note here that electrolyte-plasma polishing of threaded surface is performed at 260-310 V, electrolyte temperature of 70-85°C and current density of 0.20-0.55 A/cm2. After electrolyte-plasma processing of threaded surface the part is placed in vacuum chamber fir ion-implant processing.Ionic cleaning by argon ions is performed at 6-8 keV, current density of 100-120 mcA/cm2 for 0.2-0.8 hours and ion-implant processing of part surface by ions of ytterbium or nitrogen at 20-35 keV.

EFFECT: higher wear resistance and antifriction properties.

12 cl, 1 ex

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