The method of processing at least one piece of magnetic material


(57) Abstract:

The method of processing at least one piece of magnetic material includes placing the parts in the closed reaction chamber pulsed plasma installation, and then without intermediate transportation carrying out annealing the parts at 700-950°C and forming on her snoozing layer at 500-800°C in the same reaction chamber. Regardless of the sequence of operations annealing and formation of snoozing layer is carried out for each other. Different sequence of operations: first annealing, and then forming snoozing layer or annealing and formation of snoozing layer are at the same time. The annealing should be carried out in a vacuum or in the presence of an inert, noble or reducing gas, and snoozeworthy layer is produced by plasma nitriding. The method can be applied to obtain the anchors or the cores of magnetic chromium steel. The proposed method is more economical than the preceding, because it does not require the transport of parts between the individual processing steps, which allows to reduce the need for space for storage and costs, and is worn to the processing method, at least one piece of magnetic material according to the restrictive part p. 1 formula. Already known method (application Germany N 3149916 A1), which is made of magnetic material anchor fuel injector to increase its wear resistance harden in certain areas by nitriding. This decision - wear protection nitriding - provides optimal switching functions of the electromagnetic valve, if only due to the production of the deterioration of the magnetic properties will not be eliminated by annealing. The disadvantages are that the double heat treatment leads to increased costs, between annealing and nitriding requires intermediate storage of parts and transportation, and there is a danger of damage, and after annealing the surface of the parts may be dirty.

There is also known a method (application Germany N 3016993 A1), which is made of magnetic material anchor partially harden by cementation. Manufacturer of anchors using cementation has the disadvantage that the armature is magnetized and thereby undesirable way deteriorates the functioning of the solenoid valve.

There is also known a method (stated the manganese 7,8-24,5%, while its surface is at least partially attirbute plasma or the so-called ion method. Such steel may not, however, serve as a material for the armature or core of the solenoid valve.

Advantages of the invention

The method corresponding to the invention, is characterized by distinctive features p. 1 of the claims and is compared to known the advantage that it is particularly economical, since for processing soft magnetic parts by annealing and get snoozing layer does not require transportation between the individual processing steps that can reduce the need for space for storage and costs, and eliminates the contamination of the surface after annealing.

Given in dependent clauses signs characterize preferred modifications, and improvements described in paragraph 1 of this method.

Preferably, if regardless of the sequence of operations to carry out annealing and getting snoozing layer one after another, in particular the annealing before receiving snoozing layer, resulting in the reaction chamber independently of each other may be created optimal atmosphere for first annealing is W ill result also inert, the reducing gas or a mixture.

Preferred for obtaining snoozing layer parts are all means of thermal treatment in a furnace, such as nitriding, carburizing or other means of education snoozing layer.

The duration of the method is the preferred way to reduce, if annealing and getting snoozing layer is carried out simultaneously with the annealing temperature.

Preferred is the manufacture of parts made of magnetic or ferritic chromium steel. Preferred is also the use of processed according to characteristics of the PP 1-8, details as armature or core in the valve with solenoid control or the fuel injector.

Brief description of drawings

Summary of the invention in simplified form illustrated in the drawings and explained in more detail in the following description. The drawings show the following: Fig. 1 - fuel injector; Fig. 2 - solenoid valve; Fig. 3 - a device for implementing the method according to the invention; Fig. 4 is a graph of temperature against time corresponding to a known method; Fig. 5, 6 - graphs of the temperature of the of the examples run

Is depicted in Fig. 1 as an example fuel injector with solenoid control for fuel injection systems of internal combustion engines (ice) contains toplevelpackage the pipe 1, serving as a core and partially surrounded by the excitation coil 2. With the lower end 3 toplevelpackage pipe 1 concentric with the longitudinal axis 5 of the nozzle is sealed by welding connected tubular metal intermediate piece 6, which his converts from toplevelpackage pipe 1 by the end covers of the tubular connection piece 1 and hermetically connected by welding. In located downstream end of the inner bore 9 of the connecting part 7 is inserted cylindrical body 8 of the saddle nozzle tightly United by welding. The body 8 is made saddle nozzle 11, interacts with the locking body 12 of the injector. Downstream from the seat 11 in the body 8 is made of at least one injection hole 13, through which, when open nozzle fuel injected in the intake manifold or cylinder internal combustion engine. Shut-off body 12 made in this example in the form of a ball connected to one end of a connecting pipe 15 by welding or soldering, whereas with others the 12, the connecting tube 15 and the anchor 16 are that the internal bore 9, the connecting part 7. Tubular anchor 16 is directed guide flange 17 of the intermediate part 6. In a through bore 19 toplevelpackage pipe 1 is inserted an adjusting sleeve 20, which rests against the return spring 21 supported at one end on lying in the anchor 16, the ends of the connecting tube 15 and the loading, thereby locking the body 12 in the direction of the seat 11, i.e. in the closing direction of the valve. Made of soft magnetic material toplevelpackage the pipe 1 has turned to the anchor 16 and the end 3 end surface 23 and the anchor 16 is converted by the end of the 3 end surface 24. The end surface 23 toplevelpackage pipe 21, the end surface 24 of the anchor 16 and the cylindrical periphery 25, at least in the zone of the guide rib 17 is supplied snoozester layer, which prevents the removal of material from the periphery 25 of the armature 16 or blow each other end surface 23 of the core and the end surface 24 of the anchor, since the excitation coil 2, the armature 16 moves against the force of the return spring 21 to toplevelpackage the pipe 2 up until its end surface 24 will not run into Torsade 11 and thus, the opening of the nozzle.

The excitation coil 2 is surrounded by at least one guiding element 27, which is made in this device in the form of staples, serves as a ferromagnetic element, is held in the axial direction along the length of the excitation coil 2 and, at least partially, radially covers it. The guide element 27 rests against one end in toplevelpackage the pipe 1, and the other in the connecting part 7 and is connected with them by means of welding. Part of the nozzle is surrounded by a plastic sheath 28, which passes axially from toplevelpackage pipe 1 to the excitation coil, and at least one guide element 27 reaches the connecting part 7. Using a plastic shell 28 is formed of an electric plug-in connector 29, which is arranged to contact with the excitation coil 2 and an electronic control unit (not shown). In a through bore 19 toplevelpackage pipe 1 is inserted in a known manner the fuel filter 30.

Is depicted in Fig. 2 solenoid valve 33 is installed in hydro - or pneumotropica, such as automatic transmissions, anti-lock brakes, steering mechanisms for steering systems regularity valve 33 includes a soft magnetic core 34, surrounded in the axial direction of the sleeve 35. The sleeve 35 is wearing the excitation coil 36 with the frame 37, facing away from core 34 bold flanged end 39 which is made of the connecting pipes 40, 41. The pipe 40 is made of a flow channel 42, and the pipe 41 is a flow channel 43, which communicated with custom adjacent the end 39 of the valve chamber 45. Flow passage 43 communicates with the chamber 45 through the saddle valve 46. The saddle 46 is opened or closed by a needle valve 47, which serves as a shut-off body, protruding into the chamber 45 and is connected to the converts from seat 46 with the annular armature 48, made of magnetic material. The anchor 48 is installed in the sleeve 35 slidable and end resting in the seat 46 of the needle 47 is removed from the core 34 along the axis. In the core 34 rests against the return spring 49, which his converts from him by the end affects the saddle 46 and presses him the needle 47. The core 34 is turned to the anchor 48 end surface 51, and the anchor 48 is directed to the core 34 of the end surface 52 and on the metal shell 35 of the cylindrical periphery 53. The end surface 51 of the core 34, the end surface 52 of the armature 48 and its periphery 53 is supplied with snoozerpedic and the end surface 52 of the anchor when the excitation coil 36.

Magnetic toplevelpackage the pipe 1, the anchor 16, the core 34 and the anchor 48 is made, for example of chrome steel. Some compounds chromium steels are given in table.

These parts 1, 16, 34, 48 after processing annealed, and then slowly cooled down, which largely eliminates encountered during processing hardening and deterioration of magnetic properties. The temperature of the annealing lies in the range 700-950oC, mainly 750-850oC. in Addition, parts 1, 16, 34, 48, at least, subject to wear in the areas that they hit or slip fitted snoozester layer. Such snoozeworthy layer obtained by processing the surface or boundary layer parts, which makes the surface more rigid and resistant to abrasion. This can be used different ways. Preferred are nitriding, carburizing or coating.

In Fig. 3 schematically shows a device 56 for processing, in which the method according to the invention. The device 56 comprises a base 57, which is hermetically installed the cap 58 of heat-resistant steel. The cap 58 is surrounded by a heating coil 59, located in teploizol the base 57 of the reaction chamber 61, which can be sealed from the outer atmosphere. Reaction chamber 61 is evacuated through the suction pipe 63 by means of a vacuum pump 61. The suction nozzle 63 is arranged to close the shut-off valve 65 with electromagnetic control. Through the inlet 66 to the reaction chamber 61 can apply the necessary process gases (e.g., for plasma nitriding argon, hydrogen and nitrogen), taken from sources 67. Inlet 66 is arranged to close the shut-off valve 68 with electromagnetic control. In the reaction chamber 61 is directed to the fan 70 to the actuator serving to circulate installed it gas atmosphere. On the basis of 57 electrically isolated from him pinned directed to the reaction chamber 61 device 71 for placing parts made, for example, in the form of a rack. The device 71 includes, for example, several fixed at a distance one above the other bearing plates 72, which are boarding devices 73 for fixing the workpiece 1, 16, 34, 48. The device 71 is electrically connected to the cathode-pulsed plasma generator 75, and this electrical connection carora 75, managed electronic computing and control unit 76 is attached to the sensor 77, the pressure in the reaction chamber 61, through which the pressure can be adjusted by appropriate control of the vacuum pump 64, and a shut-off valve 65 or 68 and the gas springs 67. The temperature sensor 78 on one of the parts 1, 16, 34,48 and the temperature sensor 79, mounted, for example, on the wall of the cap 58, serve to regulate the process temperature in the reaction chamber 61 by recording the results of measurements of electronic computing and control unit 76 and to control its winding 59.

Design and operation of pulsed-plasma installation in themselves known, for example, application Germany N 2657078 or 2842407. Still processing soft magnetic parts shown in the diagram of Fig. 4, where the abscissa plotted the time t and the ordinate axis is the temperature T. however, the processing of soft magnetic components in two different operating independently of other units, one of which can be performed in a furnace with a protective gas or vacuum annealing furnace parts, and the other in the form of a pulsed-plasma installation to obtain snoozing layer. temperature, as indicated by the length 90 of the heating curve depicted. Upon reaching the desired temperature the item for quite a long time b annealing annealed at this temperature in accordance with the cut 91 annealing. While in the oven or create a certain atmosphere (e.g., inert gas) to protect against any changes in the composition of the material or vacuum. After annealing in the course of time with cooling section 92 of the cooling carry out the cooling of the part to room temperature. After a time d transport and intermediate storage, for example, in a pulsed-plasma installation over time with heat re-heating the details on the plot 93 heat, until it reached the required nitriding process temperature. Snoozeworthy layer receive during the time of formation of the layer on the section 94 of the education layer. In conclusion, during the time f cooling cooling section 95 part is cooled to room temperature.

The following describes saving time and energy and, thus, are associated with lower cost ways corresponding to the invention, in which the annealing and getting snoozing layers occur in the same processing device, to amestoy steel placed in the reaction chamber 61 and includes a mounting devices 73. Then the reaction chamber 61 vacuum and, if necessary, creates a certain atmosphere, for example, by means of inert gas that protects against any changes in the composition of the material. Electric heating coil 59 is controlled by the computational and control unit 76 so that after a certain time of heating in the reaction chamber 61 is set to a temperature corresponding to the desired temperature annealing 750-850oC.

The processing mode according to the first method corresponding to the invention, is illustrated in the shown example the graph in Fig. 5. It is necessary only the first time d heating to the desired annealing temperature along the line segment 90 of the heating, the second heating time disappears. During the time b annealing at site 91 annealing, mostly at a constant temperature or in vacuum or in the presence of an inert, noble or reducing gases or their mixtures is annealing. Then within a short period of time, h temperature decrease at site 96 temperature is reduced to the optimum for obtaining snoozing layer temperature. At this temperature plasmas is time f formation layer on the section 94 of the education layer. So, obtaining a wear-resistant layer by plasma nitriding occurs at a temperature of 500-800oC. To obtain snoozing layer should be established in the reaction chamber 61 emit nitrogen atmosphere, for example by typing molecular nitrogen and hydrogen. Over time f formation layer using a pulsed-plasma generator in the reaction chamber 61 to cause glow discharge, resulting in the collision of nitrogen ions with parts 1, 16, 34, 48. Thus, the nitrogen diffuses from the surface into parts and tempers them with education snoozing layer, which goes into detail on a certain depth. At the end of time f layer formation over time g cooling section 95 cooling is cooled to room temperature. The method corresponding to the invention and illustrated in Fig. 5 yields compared with the previous method, illustrated in Fig. 4, the time savings at the t1and, thus saving energy and costs. Due to the fact that the annealing and getting snoozing layer occurs in the same reaction chamber without the need for an intermediate transport details excluded damage or contamination of processed over a and h heating section 90 of the heating is to heat the parts to a temperature suitable for annealing and get snoozing layer, for example, by nitriding. During the time k processing section 97 processing simultaneous annealing and getting snoozing layer suitable for this purpose, atmosphere and at a suitable temperature. Then the items within time cooling section 92 of the cooling cooled to room temperature or the second cooling time fall away, so that in comparison with the first variant of the method illustrated in Fig. 5, it saves time t2resulting in additional energy savings and costs. The methods illustrated in Fig. 5, 6, may be implemented in the device for processing according to Fig. 3.

In Fig. 7 shows a fragment of the planting device 73 having a locking blind hole 81 into which is placed the workpiece 1, 16, 34, 48. As shown in Fig. 7, item 1, 16, 34, 48 partially protrudes from the hole 81. If the end surface 83 parts 1, 16, 34, 48 to provide snoozester layer 84, the hole 81 perform such depth that the end surface 83 ended approximately flush with the upper side 82 of the landing device 73, i.e., to the upper side 82 and the end surface is to perform, at least near the top side 82 so that its width does not exceed 0,05 - 0,5 mm

Instead of the described plasma nitriding snoozeworthy layer can also be obtained through the so-called gas nitriding. For this purpose establish a temperature in the range of approximately 900oC, and as a gas in the reaction chamber and injected ammonia. When gas nitriding is not electric contact parts, which saves costs. To obtain snoozing layer can be used, for example, gas carburizing, plasma carburizing methane or propane as an ambient gas for asterousia carburizing gas mixture of carbon emitting gas (CO, CO2, endo - or Ecogas) and ammonia.

1. The method of processing at least one piece of magnetic material by annealing and get snoozing layer, wherein the item is placed in the closed reaction chamber pulsed plasma installation, and then without intermediate transportation spend annealing the parts at 700 - 950oC and forming on her snoozing layer in that the reaction chamber at 500 - 800oC.

2. The method according to p. 1, on avodat each other.

3. The method according to p. 2, characterized in that the first conducting annealing, and then forming snoozing layer.

4. The method according to p. 1, characterized in that the annealing and the formation of snoozing layer are at the same time.

5. The method according to any of paragraphs.1 to 3, characterized in that the annealing is carried out in a vacuum.

6. The method according to any of paragraphs.1 to 3, characterized in that the first vacuum reaction chamber, and then into the reaction chamber and injected inert, noble or reducing gas or their mixture, after which the annealing is carried out in the presence of this gas.

7. The method according to any of paragraphs.1 to 4, characterized in that snoozeworthy layer is produced by plasma nitriding in the reaction chamber.

8. The method according to any of paragraphs.1 to 4, characterized in that the item is made from soft magnetic chromium steel.

9. Anchor designed for valve made with the solenoid or the fuel injector with solenoid control was made using the method according to one or more paragraphs.1 - 8.

10. The core is designed to valve, made with a solenoid or the fuel injector solenoid, which is made with applied


Same patents:

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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: processes.

SUBSTANCE: invention can be used with manufacturing of cutting tools, products of triboengineering function, heavy loaded machinery and mechanisms. Coating is applied by means of displacement of low-temperature plasma stream, containing carbon, silicon, hydrogen, nitrogen, oxygen and argon, lengthwise the product surface. Products are preheated up to the temperature 50-100°C. Displacement of low-temperature plasma stream is implemented at a rate of 3-150 mm/s. Total time of coating is assigned depending on processing surface area and coating thickness.

EFFECT: ensured by coating of thin-film wear-resistant coating with defined thickness with high adhesion to the basis it is achieved useful increase of product's service durability by increased reproducibility.

4 tbl

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy field, particularly to surface treatment, particularly, to nitriding steel products and can be used in mechanical engineering for surface hardening of machines. Products are placed into tank, filled by nitrogen-containing medium. Then on product, which is cathode, and anode it is direct voltage fed for creation between product and electric field anode and it is implemented saturation process of product's surface by nitrogen. In the capacity of anode and nitrogen-containing medium it is used electrolytic solution from following row of substances: sal ammoniac solution, ammonia solution. Before saturation process of product surface by nitrogen it is implemented smooth variation of voltage in the range 15-150 V. Saturation is implemented at voltage increasing in the range 150-315 V. Nitriding is implemented at atmospheric pressure.

EFFECT: it is simplified nitriding process and it is increased its rate.

1 tbl, 3 ex

FIELD: metallurgy.

SUBSTANCE: invention refers to heat treatment. The structural component out of hardened heat resistant steel is subject to heat treatment consisting in hardening of structural component, in tempering of its boundary layer, in quenching and in additional low temperature cooling; also hardening of the structural component and plasma-ion tempering of the boundary layer are carried out per one production stage by means of heating of the structural element to common temperature of hardening and diffusion Th+d above upper critical temperature Ac3, further holding is performed at this temperature till complete austenisation and release of contained carbon and also till desired saturation of boundary layer with a diffusion element.

EFFECT: production of structural component possessing high strength, toughness, higher hardness of boundary layer and therefore with higher fatigue limit.

13 cl, 3 dwg

FIELD: process engineering.

SUBSTANCE: invention relates to machine building, particularly, to combined chemical and thermal processing of machine parts. Proposed process comprises cyclic cementation of parts and their quenching. Before cyclic cementation preliminary heat treatment and mechanical processing are executed including normalisation at 950°C, high tempering at 670°C, quenching from 1010°C, high tempering at not less than 570°C and plastic upsetting at, at least 700°C at deformation degree of 50…80%. Cyclic cementation is performed with alternation of saturation and diffusion curing, at least 12 cycles of 30 minutes duration. The number of cycles depends on required depth of diffusion ply while saturation-to-curing interval ratio makes 0.1 to 0.2. After said cementation, conducted are high tempering, quenching in oil, cold processing at -70°C and threefold tempering at 510°C. The, ion-plasma nitration is performed in temperature rage of 480…500°C for at least 10 hours at the following parameters: cathode voltage at cathode spraying of 900 V, in saturation mode - 400 V, current density of 0.20…0.23 mA/cm2, has medium composition - nitrogen-hydrogen mix with 95% of nitrogen and 5% of hydrogen, gas mix flow rate of up to 10 dm3/h, chamber pressure at cathode spraying - 13.3 gPa, at saturation - 5…8 gPa.

EFFECT: higher surface ply wear resistance, longer life.

1 ex

FIELD: metallurgy.

SUBSTANCE: invention relates to production of hardened alloy with metal base and nanoparticles dispersed therein, at least 80% of which feature mean size of 0.5-50 nm. Said nanoparticles contain at least one nitride selected from nitrides of at least one metal M selected from the group including Ti, Zr, Hf and Ta. Claimed process comprises the steps that follow. a) Plasma hardening of the main alloy is performed at 200-700°C for adding thereto of imbedded nitrogen. Note here that said main alloy contains some 0.1-1 wt% of metal element M and is selected from austenite, ferrite, ferrite-martensite alloy or nickel-based alloy. b) Imbedded nitrogen is diffused in said main alloy at 350-650°C. c) Nitride is isolated at 600-900°C for 10 minutes to 10 hours with formation of said nanoparticles dispersed in hardened alloy.

EFFECT: alloy hardened by nitride particles.

29 cl, 1 dwg

FIELD: metallurgy.

SUBSTANCE: invention relates to chemical-thermal treatment of articles from tool steel. Tool is heated in vacuum chamber in argon medium at pressure 0.2-0.67 Pa to temperature not lower than 450° and not above Ac1-(50-70) °C to ensure ion cleaning of surface, then at specified temperature of heating is performed by ion-plasma nitriding in plasma of nitrogen or argon and nitrogen gas mixture with concentration of nitrogen of not less than 20 % by two-stage vacuum-arc discharge, where current of arc is (80-100)±0.5 A, and current intensity of additional anode - (70-90)±0.5 A when tool bias voltage is within range of -50 to -900 V for 0.5-2 hours, cooling is performed in chamber, and hardening and tempering is performed at standard mode for given steel to produce a nitrated layer depth 2-2.5 mm.

EFFECT: increased depth of azotised layer over a short period of time, higher wear resistance of sharpened tool made of annealed workpieces.

1 cl, 2 ex

FIELD: electricity; technological processes.

SUBSTANCE: invention relates to electrophysical and electrochemical parts processing methods, in particular, to spark-erosion alloying with graphite electrode and ion nitration of steel parts surfaces. Method of thermally treated steel part surface hardening comprises stage of spark-erosion alloying and ion nitriding operation, wherein ion nitriding operation is carried out before or after spark-erosion alloying during time, sufficient for part surface layer saturation with nitrogen at depth of thermal influence zone to prevent hardness reducing in it. Operation of spark-erosion alloying is performed by graphite electrode at least in two stages with reduction of discharge energy at each subsequent stage. First stage of alloying with graphite electrode is performed with discharge power of 0.1-6.4 J and output of 0.2-4.0 cm2/min, and second stage of alloying with graphite electrode is performed with discharge power of 0.1-2.83 J and output of 0.2-2.0 cm2/min.

EFFECT: enabling higher efficiency without increase in roughness.

1 cl, 3 dwg, 3 tbl

FIELD: metallurgy.

SUBSTANCE: proposed line comprises nitriding zone for nitriding the said strip, a cooling zone for cooling the said strip and a heating zone for heating the said strip, located before the nitriding zone. The nitriding zone comprises positive electrodes disposed opposite the strips to generate a glow discharge, and negative electrodes disposed between the positive electrodes and the strip to generate a glow discharge. Between the positive and negative electrodes, a glow discharge is generated to form a plasma for nitriding the strip. In a particular case, the said line is made with interior nitriding zone, divided by width into strips to provide separate nitriding control within each of the divided zones. The stated method of nitrided sheet manufacturing from regular grain oriented steel is implemented using the stated link, wherein after cold rolling and before secondary recrystallization annealing, continuous plasma nitriding is performed in the strip glow discharge of grain oriented steel using the stated line.

EFFECT: nitriding degree control is ensured with high accuracy, the time is decreased required for processing, to improved magnetic properties throughout the strip are obtained.

15 cl 3 dwg

FIELD: metallurgy.

SUBSTANCE: line comprises nitriding zone for nitriding the sheet, a cooling zone for cooling the sheet, and a heating zone for heating the sheet disposed before the nitriding zone. Nitriding zone is provided with glow discharge electrodes, wherein a sheet is used as a negative electrode to be subjected to plasma nitriding by glow discharge, and glow discharge electrodes are used as positive electrode, arranged in the nitriding chamber. Nitriding zone is divided into separate zones in the proposed line in direction of sheet width for nitridation control inside each of divided zones. Manufacturing method is carried out using this line for nitrided sheet of grain oriented electrical steel, wherein after the cold rolling and before the secondary recrystallization annealing a continuous plasma nitriding from grain oriented electrical steel is carried out by glow discharge of sheet.

EFFECT: uniform nitriding of steel sheet, decreased time required to process steel sheet with stable obtaining of excellent magnetic properties throughout whole strip.

15 cl, 4 dwg

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EFFECT: prevention of blade oxidation at hot isostatic extrusion.

3 cl, 8 dwg, 3 tbl, 3 ex

FIELD: mechanical engineering.

SUBSTANCE: method comprises applying a protective covering on the metallic surface, modifying the layer of metal bulk in the vicinity of the covering to a depth of at least 0.2 mm, and making the interface sublayer between the modified layer and covering, which contains both the modified structure and agent for protecting covering.

EFFECT: enhanced corrosion resistance.

1 ex

FIELD: working of steel products, possibly restoration of worn surfaces of cylindrical articles such as cylinders of sucker rod depth pumps.

SUBSTANCE: method comprises steps of mechanical working, iron plating of inner surface of article, carburization, chrome plating and further heat treatment with isotermal soaking at temperature of obtaining large-flake pearlite.

EFFECT: restoration of geometry parameters of inner surface of worn cylindrical articles, enhanced strength and predetermined surface roughness of articles.

FIELD: metallurgy; methods of treatment of surfaces of current-conducting materials.

SUBSTANCE: proposed method consists in heating the surface with alternating current at duration of current pulses of 20-100 ns and amplitude ensuring depth of fusion of surface of 1-10 mcm.

EFFECT: possibility of control of hardness, wear resistance, fatigue and corrosion resistance.

3 dwg, 1 ex

FIELD: chemical and heat treatment processes, namely nitriding parts of construction steels in gas medium, possibly in machine engineering and other branches of industry.

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EFFECT: increased rigidity and wear resistance, lowered fragileness of surface layer of parts of construction steels.

1 tbl, 1 ex

FIELD: corrosion protection of metals; protection of steel gas and oil pipe lines against corrosion.

SUBSTANCE: proposed method includes preparation of pipe edges, drying, cleaning, machining of internal surfaces of pipes, finish cleaning, application of main metallic coat near edge of pipe followed by application of additional coat overlapping the first one, heating the pipe to melting point of insulating plastic coat and applying one layer of insulating plastic coat on inner surface of pipe partially overlapping the main metallic coat; machining of outer surface of pipe, cleaning and applying layer of insulating plastic coat and erecting the pipe line; then, pipe edges are heated and aligned, after which they are welded and root runs of the weld seams are machined; welded joint is heated and filling and facing layers of weld seam are welded; then, they are cooled and non-insulated outer surface of pipe is protected by plastic insulating coats. According to another version, melt of polymer composition is applied on heated surface of pipe, after which plastic bearing and centering rings are wound on pipe and are rolled to it. Ratio of height, width of top and base of bearing ring to pipe outer diameter is equal to 1: (0.01-1.35); 1: (0.07-1.6) : (0.1-2.0), respectively; ratio of width of top and base of bearing ring is equal to 1 : (1-2.0); after erecting of pipe line, protection of its inner surface is effected by pumping an inert medium through it.

EFFECT: low labor input; improved quality of corrosion protection; enhanced reliability of pipe lines.

14 cl, 4 dwg, 4 tbl