DE1521237B1 - Workpieces and components made of ferrous materials with a wear layer and process for their production - Google Patents

Description

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The invention relates to workpieces and components that are packed and heated on solid thinning agents The basis of ferrous materials with a chromium are used to diffuse the chromium up to the diffusion wear layer and a method of striving for depth of engagement. But it is also possible to produce the gas before diffusion diffusion, i.e. a chromium-releasing gas atmosphere, use chromium plating, nitrogen plating or carbonitriding 5 for this. With this diffusion chrome plating takes place. there is a tempering of the ferrous materials, so that it

From "Blast furnace and steel plant", 38, 1950, p. 1137, it is useful after the diffusion chrome plating a method is known to make chrome steels with relative hardening.

low carbon content (maximum 0.8% C) with As iron material according to the invention are suitable

To provide a wear layer by using a wide variety of steels and alloyed steels on the surface lent is embroidered. In this way one obtains im with high carbon contents, namely over 0.4%, in the best case a surface layer made of chromium nitride. z. B. (SAE 52100) with 0.98 to 1.1% C, 0.25 to 0.45%

The USA. Patent 3 010 856 brings a Ver Mn, up to 0.025% P, up to 0.025% S ₅ 0.2 to 0.35% Si and go to the production of friction wheels for the production of 1.2 to 1.6% Cr . Such steel is often used as a spark, with ferrous material first being the material for bolts and tenons. If steels with the formation of a chromium diffusion layer are chrome-plated and a lower carbon content is used, then carburization is observed. This carburization increases the ductility of the wear, a middle zone of iron chromium carbide layer is achieved compared to an increase in hardness, which and a surface zone essentially consists of.

Chromium carbide. The workpieces or components become the wear layer

The invention now brings workpieces and components expediently thoroughly cleaned, burrs and abraded on the basis of ferrous materials with respect to surface roughness, and then the present invention substantially harder a known wear layers first step - that is ™ wear layer, and a large technically possible, the nitriding or carbonitriding - Subject to the process for the production of these with the new 25 According to the invention, one can have a working depth or wear layer provided workpieces. Produce the hardening zone to the desired extent, e.g. B. inventive workpieces and components have an approximately 76 μ. After the wear layer has been applied, the wear layer, essentially made of iron chrome, is hardened to the desired hardness. The carbides of the invention in which a phase consisting essentially of workpieces or components, such as chromium nitride, is embedded. To 30 mentioned, characterized by special hardness. A customary production of the wear layer according to the invention diffusion chromium-plated bolt has z. B. one is embroidered on the surface of the iron material or surface hardness of 1200 to 1300 HV, one is carbonitrided and then after the diffusion of the same bolts with the comparative method according to the invention, a chrome layer is applied. Carbon layer, however, significantly above 1500 HV. If the carbon level rises, this hardness nitriding can be attributed to the intermediate zone according to the invention, corresponding to a carbon content of the ironworks made of chromium nitride. Substance to be carried out. After the diffusion To carry out the inventive method

The ferrous materials can be chromed or, for example, an extruded blank can be used in construction parts still harden. made of a high carbon steel or alloy steel

The materials according to the invention are suitable for machine sequences that are subject to heavy wear and tear because of their particular hardness and wear-resistant parts. The blank is placed on the desired surface for such machine parts that are not only cut to length, then carefully cleaned and subjected to very high levels of wear and tear, but also very high pressure in an oven to remove all moisture, i.e. components from different bearings Heated between 93 and 121 ° C. \

such as bearing rings, high-speed bearings, drainage plates 45 The test specimens are then placed in shallow baskets, for rolls and rollers and various parts of e.g. B. embroidered in an oven, with ammo clutches, where niak to the workpiece surface or by another known method high stresses in terms of pressure and relative to the embroidery of steels at 835 to 843 ° C, and speed is set. about 90 to 100 minutes at a temperature

Leave the excellent properties of the invention 50 speaking of the desired hardness, appropriate wear layer are at least partially. It is then quenched, further cooled and used

the inseparable connection of this wear layer relaxation drawn or stretched, attributed to the workpiece itself. Such an intimate well is the diffusion-

Connection is with superficial chrome plating, z. B. made chrome plating and then through Electroplating is not possible, only the in-55 hardens to the extent that the tempering treatment in the chrome plating by diffusion process leads to chrome plating to regain lost hardness, so extensive connection that peeling apart from these process steps can

Wear layer cannot take place. The good ones still include deburring, grinding grooves, finishing mechanical properties of the machining according to the invention (with the exception of the work surfaces) or The wearing course is also partly based on the 60 material testing takes place, Chromium embedded in the chromium diffusion layer.

nitride layer. purifies.

The diffusion chrome plating, so the second stage. The figure shows a photomicrograph of one for

of the method according to the invention, a conventional grain boundary etching with 1 to 2% alcohol Diffusion chromium plating process, i.e. ground cut of steel SAE 65 treated with nitric acid neither an insert chrome-plating, in that the movement 52 100 in 2000x magnification, pieces or components in a chromium-releasing powder, the workpiece 10 z. B. made of steel SAE 52 100 with

z. B. chromium halide, in a mixture with a fire- 1% C was in a strongly carburizing atmosphere, both

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For example, with a carbon potential of 1.5 ° / ₀ C, the oil bath should be approximately

carburized, it forms a large number of iron 32.2 to 54 ° C and not above about 66 ⁰ C

chromium carbide inclusions 12 in a relatively high concentration. You should only start with air cooling

tration near the outer modified chromium- when the batch reaches the oil temperature below 66 ° C

or insert layer 14 and into the workpiece 5; air cooling is continued up to 23.9 ° C

one that determines an inner support structure for the modifi- and at room temperature equal the hardness,

lead decorated chrome layer. However, at this point in time, the workpieces will have a

Embroidered in a relatively carbon-neutral environment, so Rockwell hardnesses are 93 to 94 (15 N).

such iron carbide inclusions are less pronounced. In the example above, the nitration time is

This is the case when the carbon level of the hardened steel is specified; it is tempered

carbonic atmosphere lower the carbon content of the steel under otherwise identical conditions. These

Steel reduced to less than 1 ° / "and therefore no shortened time of nitriding is also for the carbon

Carbon migration through the steel structure instead of nitriding of hardened steel in a carburizing process

bark. Atmosphere (e.g. from a pre-batch) can be used.

The chromium-plated layer 14 comprises a lower 15 final hardening after the chromium diffusion

Zone 16 of iron chromium carbide in solid solution, which can be done in any way, in general

approximately in the middle an intermediate zone 18 made of grain but under conditions similar to nitriding or

plexem chromium nitride, which is clearly darker from carbonitriding, with the exception of the carbon and

draws and shows in a color photomicrograph of an ammonia-containing furnace atmosphere, e.g. E.g .: dew point

ground etched with alcoholic nitric acid pink 20 1.6 to 4.5 ⁰ C; Fission gas: (no ammonia) dew point

appears. The mounting part 20 was only used for polishing 1.6 ± 2.5 ° C at 830 to 843 ° C for at least

and etching the ground joint. Anyway the 60 minutes, quenching in oil, cooling in the air

mechanical influence of this intermediate zone or phase and stretching at 149-160 ⁰ C.

the nitride, it causes an increase in hardness. Workpieces treated in this way show a core

and wear resistance of the chromium diffusion layer. 25 hardness of at least 60 HRC or at least

The method according to the invention is now carried out at 90 HRN and on the surface according to K η ο ο ρ 1350

Manufacture of wear-resistant coupling parts from a test load of 100 g.

SAE 52100 explains: The determination of the microstructure resulted in a

The crude molded body is cut, cleaned, dried intermediate phase 18 with a thickness of about 20% and at 93 to 121 ⁰ C. It is embroidered 30 the thickness of the entire chromium diffusion layer 14 and (or carbonitrided). The temperature should be above the spherical carbide inclusions 12 immediately below the lower critical point, e.g. B. at 835 to 843 ⁰ C, diffusion layer 14 in the core of the workpiece,
the dew point of the furnace atmosphere is maintained at -12.5 ± 0.5 ° C. The chromium layer 14 according to the invention shows. For a chromium diffusion layer, the furnace atmosphere forms a compound with the base material that is characteristic of a fission or synthesis gas, natural gas and ammonia, which means that with a throughput of fission gas of 5.66, no peeling, flaking or the like, as is the case with elekbis 6, 37 m ³ / h, on natural gas of 1.13 m ³ / h or above trolytic chrome plating is the case, takes place. The and of ammonia of 0.255 m ³ / h. The reaction time surface has extreme hardness and wear resistance should be 90 to 100 minutes. Then it is quenched on a steel <0.4 ° / ₀ C oil bath at 32.2 to 54 ° C and in 40 ductile and thus further applications permitting air is slowly fully cooled and only for loan. The surface is very corrosion and scratch-relieving internal stresses at room temperature 3 to solid. The dimensional accuracy of the workpieces is not left to stand for 4 hours and then influenced at 163 to 177 ° C, any changes are easily foreseen. (For e.g. parts <45.4 kg at least 2 hours.

den.) The workpieces treated in this way are 45. The spherical inclusions 12 seem complex

Hardness tested to be tumbled to remove the burrs, ferric chromium carbides, which are from the constituents

Grooves or the like ground in. The special alloy itself or completely or at least is chrome-plated

up to an application depth of 76 μ, whereby this depth can partly originate from the chrome layer 14,

will measure. Finally, hardening takes place in order to improve the superiority of the inventive method

Chromium diffusion-related tempering reversed to show 50 driving was done according to the instructions of the

do. Measures now follow to determine USA.-Patent 3,010,856 a wear layer

determination of hardness, surface quality, dimensional accuracy and according to the chromium diffusion process and subsequent

for errors with the help of the magnetic particle process. the carburization and thereby a wear and tear

At the beginning of the nitration, the atmosphere must reach a layer with a thickness of 17.8 μ. The upper

not be carbon free; in some cases it is 55 surface hardness of the wear layer at a

desirable immediately after a carburization in the test load of 10 kg according to K η ο ο ρ 2760, the hardness of the

Furnace to continue working. This makes the batch time of the steel core 62 HRC.

reduced under certain working conditions. The treatment according to the invention was subjected to a previous heat treatment 60 52 100 (0.98 to 1.1 ° / ₀ C, 0.25 to 0.45 ° / ₀ treated in a relatively neutral steel according to the American specification SAE atmosphere , a longer period of use is required. Mn, 0.025 P, 0.025 S, 0.20 to 0.35% Si, 1.3 to 1.6 ° / ₀ A dew point of -4 ⁰ C or below corresponds to Cr). The wear layer held by the process according to the invention at a carbon level of 1 ° / ₀ , in the case of large-scale industrial applications, had a thickness of 5 μ. However, the procedure is a dew point of about -12 ⁰ C This was desirable for determining the hardness of the part. The dew point of the furnace atmosphere 65 layers divided into the outer partial layer, the middle layer is at the beginning and end of the carbonitriding to form a partial layer, the inner partial layer. Determine at a test load of. A batch should not be significantly more than 10 kg for the outer sub-layer according to kg. K η ο ο ρ an average of 2640 for which

middle sub-layer of 3200 and for the inner sub-layer of 2721.

Comparing the hardness numbers from the inventive process with those of the known method, it is found that the hardness of the outer partial layer is smaller by about 4.3 ° / ₀ as known from the procedure. The middle sub-layer is a 15.9% greater hardness and the internal sublayer a 1.4 ° / ₀ lower hardness than the wearing layer according to the known method. The graduated hardness of the wear layer according to the invention is particularly useful for bolts and the like that are subject to high loads, namely because the relatively softer outer part-layer rests on the extremely hard middle part-layer.

Claims (4)

Patent claims: 1. Workpieces and components based on ferrous materials with a wear layer, characterized in that the wear layer is a layer consisting essentially of iron chromium carbides, in which a layer consisting essentially of chromium nitride is embedded existing phase. 2. Process for producing the wear layer on the workpieces and components according to Claim 1, characterized in that the iron material is embroidered or carbonitrided on the surface and then a chrome layer is applied according to the diffusion process. 3. The method according to claim 2, characterized in that the carbonitriding in one Carbon level is carried out according to the carbon content of the ferrous material. 4. The method according to claim 2 or 3, characterized in that the ferrous material according to the Diffusion chromating is hardened. 1 sheet of drawings