JPS5983761A - Wear-resisting iron and steel product - Google Patents

Abstract

PURPOSE:To obtain iron and steel products having wear resistance, by a method wherein N2 dispersed surface layer is formed on steel products and the layer of high hardness metallic compounds such as TiN, TiC, etc. is formed on the surface thereof. CONSTITUTION:The N2 dispersed surface layer where, for example, acicular crystal of gamma'-Fe4N is dispersed in ferrite structure is formed near the surface of steel products. The layer of high hardness metallic compounds such as TiC, TiN, etc. is formed on the surface of said N2 surface layer. The N2 dispersed surface layer can be obtained by the selection of treating conditions on gas phase surface treatment in N2 atmosphere and the layer of metallic compounds can be expanded by, for example, sputtering treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steel product having 1ψ4゛L resistance.

Conventionally, as means for improving the surface hardness and wear resistance of steel, there have been methods such as (al) thermal spraying of high melting point metals such as molybdenum and tungsten, (bl) electroplating such as hard chrome plating, (c) carburizing and quenching, carbonitriding method,
Surface hardening heat treatment methods such as gas soft nitriding method, salt bath nitriding method, ion nitriding method, etc. (dll- after performing surface hardening heat treatment,
Mo, W, Cr, Ti, Ni.

A double coating treatment method, etc., in which TiC, TiN, etc. are coated by an ion blasting method, a sputtering method, etc., has been carried out. When using method (a), post-processing is troublesome, adhesion is poor, there is a risk of peeling during use, and there are problems in achieving uniform coating.

In addition, (when using the bl method, peeling is likely to occur as well, and there are problems with waste liquid treatment.) The above method (C) is relatively inexpensive and suitable for mass production, and is commonly used.
There are still problems in obtaining sufficient chipping properties.

On the other hand, method (d) above is superior to each of the above methods in terms of wear resistance, but has the same drawbacks as the single surface hardening treatment method such as method (C). There are still problems with cage adhesion.

For example, when a high-hardness metal compound layer is laminated on a carburized and quenched layer, there is a problem that the coating layer peels off due to deformation due to decomposition of residual austenite present in the carburized layer during use. When stacking on a nitride layer having a compound layer such as , N or γ'-Fe4N, these compounds j-
is brittle and easily breaks off, and the toughness of the entire part is also reduced, which poses a problem when used in practical applications under severe conditions.

In view of this point, the present invention forms only a nitrogen diffusion surface layer on a steel material, and TiC is applied to the upper surface of the nitrogen diffusion surface layer.

The purpose is to provide a steel product with good adhesion between the two layers and excellent wear resistance by depositing a layer of a high hardness metal compound such as TiN.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments and drawings.

Example/ This example is shown in FIGS. 1 and 2. Figure 1 is a micrograph of a cross section showing the microstructure near the surface of a steel product of the present invention using S/3C (carbon steel) as the matrix (however, 5%
The near surface of the steel product 1 is a nitrogen diffusion surface layer 6 in which acicular crystals 2 of γ'-Fe4N are diffused in the ferrite structure, and a high hardness T layer is directly applied thereon. A metal compound layer 4 of iN is deposited. The nitrogen-diffused surface layer 6 is obtained by selecting treatment conditions in a gas phase surface treatment in a nitrogen atmosphere, and the metal compound layer 4 is deposited, for example, by sputtering treatment.

The above-mentioned nitrogen-diffused surface layer has a hardness higher than that of the base material without losing the toughness of the steel material, and therefore reduces the difference in hardness with the metal compound layer to which it is applied, thereby improving the abrasion resistance during use. can be increased.

In addition to the above-mentioned TiN, as the high hardness metal compound layer 4,
Nitrides or carbides such as Ti, Ta, Cr, Zr, Si, etc. are used, and materials suitable for each purpose are selected.

Although the means for forming the nitrogen diffusion surface layer 6 and the metal compound layer 4 are not limited, it is preferable that they be formed continuously in a vacuum furnace.

Next, as seven examples, a sputtering device is used, S/6C (carbon steel) is used as the object to be treated, T1 is used as the material to be sputtered, and a nitrogen diffusion surface layer 6 made of γ'-Fe4N and a metal compound layer made of TiN are formed. 4 will be explained below.

As shown in FIG. 2, the sputtering processing furnace 10 is provided with a hollow target 12 in the center of a furnace body 11, and the target 12 is made of a material to be sputtered (Ti), or is made of a material to be sputtered (Ti). A support frame 14 is provided to surround the target 12 and support the steel product (S/6'C) 1 in a concentric manner, thereby preventing claw discharge during sputtering. For stabilization, a permanent magnet 15 is installed inside the target 12 and an electromagnetic coil 16 is installed around the outer periphery of the furnace body 11 so as to support a magnetic field orthogonal to the electric field formed between the target 12 and the steel product 1. are provided respectively. Further, for the sputtering processing furnace, a vacuum pump 17,
A cylinder group 18 for supplying atmospheric gas is connected to the target 12 and the support frame 14, and a polarity changer 19 is connected to the target 12 and the support frame 14 to switch the applied electrode.
The sputtering apparatus 2o is mainly composed of the sputtering processing furnace 1o, the vacuum pump 17, the cylinder group 18, and the polarity changer 19.

Note that 21 is a DC power supply.

Next, the processing procedure will be explained. First, contrary to the sputtering process, the support frame 14 is connected to the cathode, the target 12 is connected to the anode, and a DC voltage is applied to perform the reverse sputtering process. The processing conditions at this time are: Atmosphere N2:N2=/:J' (however, flow rate ratio) Furnace pressure / Torr Processing time /, 20 minutes Then, the electrodes applied to the target 12 and the support frame 14 are reversed, and the target 12 is The support frame is connected to the cathode and the anode, and a DC voltage is applied to perform the sputtering process. The processing conditions in this case are as follows.

Atmosphere: N2:N2=2:/(Flow rate ratio) Furnace pressure: jX/OTorr Processing time: 20 minutes Central magnetic field, 200 oersted The cross-sectional microstructure thus obtained is shown in FIG. 1 above.

Example! This example shows an example in which SKD 61 (alloy tool steel) is used as the steel material, and is shown in FIG. 3. However, the processing procedure is the same as in the above embodiment, and in the figure, 6 is the core part, 7
8 is a nitrogen diffusion surface layer, and 8 is a metal compound layer made of TiN.

The above embodiment/ is based on γ'-Fe contained in the nitrogen diffusion surface layer.
Although we have shown an example in which 4+'l appears as needle-like crystals within ferrite grains, these needle-like crystals of γ'-Fe, IN are found in carbon steel and cast iron where a ferrite structure exists, or in alloy tools. In steel, structural low-alloy steel, nitriding steel, high-speed steel, etc., the nitrogen-diffused surface layer 7 containing γ'-Fe4+'l is entinct black compared to the core 6. Even in this case, the hardness of the nitrogen diffusion surface layer 7 is higher than that of the core 6.
The same effect as in the tfi'7J example can be obtained.

In addition, although Example 1 shows a metal compound layer made of TiN as the surface layer, the metal compound layer is not limited to this, and examples include nitrides such as ZrN, V/N, and VN, or TiC. , ZrC, WC, VC', Ta
C.

Of course, carbides such as Cr3C2 are also possible. In this case as well, it can be formed in the same manner as in the above embodiment (however, if a carbide is to be deposited, a hydrocarbon-based gas such as 0-H8 gas is used as the atmospheric gas).

As described above, according to the present invention, the hardness is increased relative to the core by forming the nitrogen diffusion surface layer on the surface of the steel product, and since there is no brittle nitrogen compound layer, a highly hard metal compound layer is applied to the surface. Since it does not peel off during use and does not lose its toughness, the entire part does not break due to impact, and a product with good wear resistance can be obtained.

[Brief explanation of the drawing]

The drawings illustrate embodiments of the invention, FIGS.
The figures relate to Example 1; Figure 1 is a micrograph of a cross section near the surface of a steel product corroded by 5% nital; Figure 2 is an explanatory diagram of the sputter link device; Figure 3 relates to Example 2; Corroded by 5% nital near the surface! This is a microscopic photograph of a cross section obtained by 1... Steel product, 6... Nitrogen diffusion surface layer, 4... Metal compound layer, 7... Nitrogen diffusion surface layer, 8... ...Metal compound layer Fig. 3 Fig. 2

Claims (1)

[Claims] (1) A wear-resistant steel, characterized in that a nitrogen 1-7iQ surface layer is formed on the steel, and a high-hardness metal compound layer such as TiN or TiC is adhered to the nitrogen-diffusing surface layer. product.