How microscale steel with double chemical and thermal treatment

 

(57) Abstract:

The invention relates to mechanical engineering and can be used in the manufacture of steel machine parts and tools with surface hardening. The objective of the invention is to increase the hardness, heat resistance and cutting resistance of the diffusion layer. In this method of pre-processing for diffusion saturation of the surface and create a sublayer is carbonitriding at 800-820oWith the use of triethanolamine. After retracements perform nitriding thickness smaller than the thickness of the sublayer of retracements. After nitriding perform quenching, cold treatment, vacation. Control of the thickness of the diffusion layer is carried out after retracements and nitriding, and after hardening, processing, cold, and dispensing of controlled surface hardness. The carbonitriding of steel products MOI perform at 800oAnd steel OHNSMAN - at 820oC. Technical result is to increase the hardness, heat resistance and cutting properties of the diffusion layer of the products of alloy steel, and the lower saturation temperature to 800oWith network economic benefits of preservation oborudovanie structural steels instead of the instrumental. 1 C.p. f-crystals, 3 tab., 2 Il.

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

In the world practice known to use microscale, i.e. hardened nitrided parts. This includes, for example, hardening after corrosion nitriding (Metallography and heat treatment of steel and cast iron. The Handbook. M: Metallurgizdat, 1956, S. 624-626). For highly loaded parts use of medium-carbon steel with nitrosatable. Improving the wear resistance of the tool is achieved by using microscale high-carbon steels: Lakhtin Y. M. , cotan J. D. Nitriding steel. M: mechanical engineering, 1976, S. 256. As noted in this work (C. 106): "According to preliminary data is promising application of microscale to carburizing products".

The closest analogue of the invention is the method described in example 3 of the patent of the Russian Federation G 01 N 17/00, 2090861: Karpov L. P., Merchants, I. N. - the method of determining the corrosion resistance of the diffusion layer details of the structural steel. In this example, the method of chemical-heat treatment, including cementation, AZ the diffusion layers and their hardness.

The disadvantages of the method, taken as the closest analogue is the fact that the processing of this method is the embrittlement of the surface layer of the product due to the presence of solid carbide mesh cemented layer.

In table.1 provides data carbide mesh that occur during gas carburizing of a number of steels using, for example, triethanolamine at 900oC.

The objective of the invention is to increase the hardness, heat resistance and cutting resistance of the diffusion layer due to the elimination of carbide mesh, while the diffusion layer has a corrosion resistance at a significant depth of nitrided layer, and decrease the saturation temperature to 800oWith economic benefits for safety equipment, energy saving. The favorable properties of the diffusion layer will allow to produce a tool of structural steels instead of the tool.

The essential features characterizing the invention are that the method includes pre-processing for diffusion saturation of the surface and create a sublayer, nitriding, hardening, tempering, control of the thickness of diffusion layers and their powernationalist the cold treatment, as a pre-processing using the carbonitriding at (800-820)oWith the use of triethanolamine, and the thickness of the nitriding layer creates smaller than the thickness of the sublayer of retracements, the carbonitriding of steel products MOI perform at 800oAnd steel OHNM - at 820oC.

To implement the method perform the operations of:

1. Make details and samples-witnesses under the carbonitriding.

2. Perform carbonitriding using triethanolamine at 800-820oWith the modes shown, for example, in the work: Karpov L. P. Application of retracements to ensure samosatene tool in the process // Mit, 1999, 6, S. 16-19. Provided the thickness of the diffusive sublayer 0,85-1,10 mm which is monitored on samples-witnesses.

3. Remove soot from the surface details and samples by, for example, wiping, waterjet machining, galvano-chemical methods, mechanical processing, if the seam allowance. Remove the metal layer should be kept to a minimum, it is necessary to keep the thickness of retracements greater than the thickness of the layer subsequent nitriding.

4. Perform the nitriding modes "TBE is inu layer nitriding.

5. Perform the tempering by heating in molten salt (light heating) or controlled atmosphere, vacuum. Cooling takes into account the required rate of hardening. After cleaning the sample surface to a depth of not more than 0.05 mm check the hardness.

6. Perform a cold treatment at a temperature of minus 60o1 h, no later than 5 hours after quenching. Control the hardness.

7. Perform low vacation 180-200oWith controlled hardness.

8. If necessary, perform a second, high-temperature tempering.

The device illustrated by the drawings.

Fig. 1. The microstructure of the diffusion layer after nitrosable on nitrosomethane layer steel MOI.

Fig. 2. The microhardness on the thickness of the diffusion layer after microscale steel OHNSMAN on retracements (1) and nitration (2).

The way to check is almost in the development of technologies for the manufacturing of cutting tools. Legend: N/C - carbonitriding, C - cementation, KS - carbide mesh, AZ - nitriding, 3 - quenching, arr/x - cold treatment, N/OTP - low vacation/OTP - high vacation, d/p - diffusion layer, the third core, hn/Cand hAZthe thickness of the layers of retracements and the and samples of steel MOA instead of applying for a milling tool steel or high speed. The samples were polished in size 52026 mm and developed modes HTO and THEN. Carbonitriding: if 800oWith the filing of triethanolamine 65 drops/min (15 h) and 45 drops/min (2 h). Nitriding: 500oWith 15 hours and 520oC - 25 o'clock the Temperature of austenization are determined in salt 840oC, quenching in oil. Cold treatment at -60oWith 1 tsp Low vacation 180oWith - 1,5 hours Results: hn/C=0.81 mm, hAZ=0,37 mm, carbide grid point 2, i.e. embryos (table.1), the fragility is missing, the microstructure layer - Fig.1.

Analysis of hardness tested the relative resistance of the diffusion layer by heating at 500oC.

Compared the results after microscale and hardening without nitriding layer microcemento - table.2.

From table. 2 should the advantage of microscale (4 samples) the results of the increased hardness (most 895 HV effect and the relative heat resistance (most 1,47).

Developed optimal modes microscale on nitrosomethane layer of steel MOI made 4 cutters for slotting floor boards. Thickness 4-Peroj cutters at the base equal to 24 mm

Cutters work successfully showed high stability of the cutting edges and high structural strength of cores 1999, 6, S. 16-19, steel OHNSMAN with samozatachivanie. On the samples of the technology and the control of mechanical properties. In contrast to the modes described in example 1, the temperature of the H/d was equal to 820oWith, quenching 820-830oAfter low made high temper 500oWith 2-2,5 h, cooled in oil. The thickness of the layer hN/C=0,75-1,10 mm, hAZ=0,3-0,6 mm, carbide mesh absent (score 1), carbonitrides 1-2 (satisfactory), the fragility of the diffusion layer is absent. The hardness and mechanical properties is given in tab. 3, where the advantages of hardness microscale on nitrosomethane layer.

According to the developed modes nitrosatable on nitrosomethane layer made of steel OHNSMAN and tested knives supersonic having satisfactory mechanical properties (table. 3), the properties of the diffusion layer and the hardness of cutting edges: "solid" (the principle of samosatene) 610-611 HV 30 and "soft" 547-585 HV 30, when the hardness of the core 389-396 HV effect 30. In Fig.2 shows the microhardness on the thickness of the diffusion layer, which is higher after nitrosable on retracements than after nitriding and hardening (cold treatment and tempering at 500oC).

The knives tested at minus 60oWith cutting steel bars, m low temperature test, i.e. "North of execution."

1. The method of chemical-heat treatment, including pre-processing for diffusion saturation of the surface and create a sublayer, nitriding, hardening, tempering, control of the thickness of diffusion layers and their surface hardness, wherein after hardening are cold treatment, as a pre-processing using the carbonitriding at 800-820oWith the use of triethanolamine, and the thickness of the nitriding layer creates smaller than the thickness of the sublayer of retracements.

2. The method according to p. 1, characterized in that the carbonitriding of steel products MOI perform at 800oAnd steel OHNSMAN - at 820oC.

 

Same patents:

The invention relates to the field of chemical-heat treatment of heat-resistant Nickel alloys and can be used when conducting a hot isostatic pressing (CIP) of the cooled turbine blades stationary energy and transport gas turbine engines

The invention relates to the field of metallurgy, in particular to a method of chemical-heat treatment of semi - and heat-resistant die steels

The invention relates to chemical-thermal treatment, mainly to the hardening of the cast cutting tools made of high speed steel for increased wear resistance and heat resistance of the surface layers
The invention relates to radiation-beam technologies modification of materials and can be used to obtain structural materials with unique properties for use in engine-building, aviation and chemical industry

The invention relates to the field of mechanical engineering

The invention relates to the field of metallurgy, namely the combined methods of hardening metals, and can be used in the manufacture of precision parts, working in alternating loads

The invention relates to the field of metallurgy of steels, and in particular to methods of hardening metals, and can be used in the manufacture of parts made of heat-resistant alloys, running under load at temperatures up to 1100oC

The invention relates to a method of processing at least one piece of magnetic material according to the restrictive part II

The invention relates to the field of chemical-heat treatment, namely, to the nitriding processes of parts made of low carbon martensitic steels

The invention relates to mechanical engineering and can be used for heat treatment of parts made of low-or medium-carbon low-alloy steels, produced with surface hardening by carbonitriding or cementation

FIELD: metallurgy.

SUBSTANCE: it is implemented heating of products up to specified saturation temperature in the range 500-600°C 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

FIELD: metallurgy.

SUBSTANCE: it is implemented heating of products up to saturation temperature 450-780°C 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: steel article are preheated in air and held at 350°C to 400°C, 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 570°C to 630°C with subsequent cooling in exogas or oil. Then, polishing is performed to final size of the article and oxidising in air at 300°C to 400°C 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: 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=550-590°C. 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: invention relates to metallurgy, in particular, to a method of combined chemical-thermal processing of parts from a hot-strength steel intended for making high-loaded gears of reduction gears for aviation equipment serviceable at heating in the contact zone of up to 500 °C. Performed is preliminary thermal processing by normalizing at the temperature of (950±10) °C with air cooling, high tempering at the temperature of (650±10) °C with maintaining for 3 hours, cooling in the air, hardening in oil at the temperature of (960±10) °C, repeated high tempering at the temperature of (660±10) °C with maintaining for 3 hours and cooling in the air. That is followed be vacuum cementation at the temperature of 940°C and thermal hardening by quenching, intermediate temperings, cold processing and repeated tempering. After thermal hardening the saturated carbide zone is removed from the cemented layer surface by grinding to the depth of 0.2–0.25 mm, after which gas nitriding is performed at (480–500) °C.

EFFECT: provided is significantly increased contact service life (the main characteristic for heavily loaded gears), fatigue strength and wear resistance.

1 cl, 1 dwg, 1 tbl, 1 ex

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

FIELD: chemical and heat treatment, mainly of refractory nickel alloys, possibly restoration and manufacture of blade of stationary power production plants and aircraft gas-turbine engines.

SUBSTANCE: method for protecting surface of blade at process of hot isostatic extrusion comprises steps of placing blade in container and further placing it in gasostat; before hot isostatic extrusion immersing blade or its part into ceramic powder on base of refractory oxides with melting temperature 1400-2800°C and fraction size in range 0.01 - 17 micrometers.

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

Up!