JPH06340921A - Wear resistant parts for crusher - Google Patents

Abstract

PURPOSE:To improve the wear resistance and toughness of wear resistant parts for a crusher and to prolong its service life by specifying the chemical components of steel, subjecting it to excess carburizing treatment at a high temp. and dispersedly precipitating hard and fine carbides into carburizing hardened layer on the surface. CONSTITUTION:This steel has a compsn. contg., by weight, 1.0 to 1.6% C, 0.3 to 1.2% Si, 10.0 to 27.0% Mn, <=3.5% Cr, <=1.0% Mo and <=1.0% V, and the balance Fe with inevitable impurities. Furthermore, <=1.0% Ti may be incorporated therein. The surface is subjected to excess carburizing treatment in the temp. range of 950 to 1100 deg.C in an atmosphere having >=1.5% carbon potential to dispersedly precipitate spherical or acicular fine carbides into the carburizing layer, and after that, hardening is executed. In this way, the wear resistant parts for a crusher improved in wear resistance and toughness can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wear resistant part for a crusher having a surface hardened layer on the surface of a material and having excellent wear resistance.

[0002]

2. Description of the Related Art Abrasion resistant parts for crushers, such as crushing elements, receive an impact load under the crushing action and bring about progress of wear, and therefore wear resistant materials are used. On the other hand, surface hardening methods of materials are used to increase wear resistance and strength, and among these methods, carburizing hardening methods are widely used, and automobile parts, civil engineering excavation bits, various constructions, etc. It is often used for machine parts such as machine wear parts.

In the carburizing and hardening treatment method, the carbon potential of the carburized material is adjusted so that the surface carbon content of the component is approximately 0.8 to
It is made to be 1.00% by infiltration and solid solution, and then quenched to make its surface layer part a hard martensitic structure. Recently, as an improvement of the carburizing process, an excessive carburizing process in which C is infiltrated into steel to form a solid and fine spherical carbide in the austenite state at high temperature and under high carbon potential. The law has been developed (for example, JP-A-52-140435,
JP-A-61-104065, etc.).

Further, a wear resistant part for a crusher in which an excessive carburizing process is applied to a low Cr alloy is also known (for example, Japanese Patent Laid-Open No. 2-101154).

However, the above-mentioned conventional carburized parts have the following problems.

1) When the component is a cast component, the casting surface of the component is present and carbon is difficult to carburize inside. 2) When the carburizing process is performed by the gas carburizing furnace, the carburizing temperature cannot be increased, and the carburizing speed cannot be increased, which results in a long process time. 3) The thickness of the quenching layer is thin, and even if it is thick, it is about 1 to 2 mm, so in the case of wear resistant parts for a crusher, when the wear of parts progresses, the wear speed increases rapidly and the durability of parts is improved. I don't care. 4) On the other hand, the high-Mn alloys, which are most frequently used as wear resistant materials for crushing, use work hardening to improve wear resistance, and therefore have large initial wear and sliding wear. On the other hand, there is a problem that the above effects cannot be exhibited. Further, the alloy composition is unsuitable for normal carburizing and quenching, and for excessive carburizing, the alloy composition, the carburizing and quenching conditions, the effects such as the wear resistance characteristics of the excessive carburizing layer and the like have not been clarified at all. Is the current situation.

The present invention solves the above-mentioned conventional problems, in which a high-manganese cast steel is subjected to an excessive carburizing treatment at a high temperature using a vacuum carburizing method to form a hard spherical or needle-shaped fine carburized layer. An object of the present invention is to provide a wear-resistant part for a crusher, which has a surface-hardened layer in which carbide is dispersed and deposited and which is excellent in wear resistance and impact resistance.

[0007]

In order to achieve the above-mentioned object, the present invention has a weight ratio of C: 1.0 to 1.6%, Si:
0.3-1.2%, Mn: 10.0-27.0%, C
r: 3.5% or less, Mo: 1.0% or less, V: 1.0%
Hereinafter, the balance has a chemical component consisting of Fe and impurities, and the surface is subjected to excessive carburizing treatment in a temperature range of 950 to 1100 ° C. in an atmosphere having a carbon potential of 1.5% or more, and the carburized hardened layer is spherical or needle-shaped. Characterized by having a hardened layer on the surface of the material by continuously quenching after finely dispersing the fine carbide of
C: 1.0 to 1.6%, Si: 0.3 to 1.2%, M
n: 10.0 to 27.0%, Cr: 3.5% or less, M
o: 1.0% or less, Ti: 1.0% or less, V: 1.0%
Hereinafter, the balance has a chemical component consisting of Fe and impurities, and the surface is subjected to excessive carburizing treatment in a temperature range of 950 to 1100 ° C. in an atmosphere having a carbon potential of 1.5% or more, and the carburized hardened layer is spherical or needle-shaped. After the fine carbide is dispersed and precipitated, a hardening layer is provided on the surface of the material by subsequent quenching.

[0008]

The reason for limiting the component range of the base material constituting the wear resistant part for a crusher according to the present invention will be described. C: 1.0 to 1.6% C is an element necessary to secure the strength of the core of the component, and if less than 1.0%, the strength decreases. Although the strength increases as the content of C increases, the strength and the drossiness decrease at 1.6% or more, so the upper limit was made 1.6%. Si: 0.3 to 1.2% If Si has a deoxidizing effect of less than 0.3% during melting, the deoxidizing effect will be insufficient and the fluidity will be impaired, so the lower limit was made 0.3%. Si is effective because it reduces the amount of retained austenite, but if it is 1.2% or more, it has a carburizing inhibitory action, so the upper limit was made 1.2%. Mn: 10.0 to 27.0% Mn is an element necessary to secure wear resistance and strength together with C. If it is less than 10.0%, strength and wear resistance are lowered, so the lower limit is 10. It was set to 0%. Although the strength and wear resistance increase with the increase of Mn, the effect cannot be obtained in both strength and wear resistance at 27.0% or more, so the upper limit was made 27.0%. Cr: 3.5% or less Cr is effective for forming carbides, but 3.5%
If it becomes the above, the drossiness is lowered, so the upper limit was made 3.5%. Mo: 0.5% or less Mo is effective for forming carbides in the carburizing process. However, if added excessively, the carbides become coarse, so the upper limit was made 0.5%. Ti, V: 1.0% or less Ti, V is effective for refining carbides in carburizing. However, if added excessively, the dryness is deteriorated, so the upper limits were made 1.0%.

Using the above base material, a surface of 950-11
By performing high-temperature over-carburization in the temperature range of 00 ° C, C
Since it significantly diffuses into steel, the carburizing time can be shortened and energy can be saved. In addition, the carbon potential of the carburized material is adjusted to an atmosphere of 1.5% or more, and vacuum carburization is used to activate the surface of the steel at a high temperature during heating, so that the surface carbon content of the component is 2. By setting the content to 0 to 3.0%, carbide is finely dispersed and precipitated. By using the vacuum carburizing method, it is possible to avoid a decrease in the hardness of the surface hardened layer due to the generation of a grain boundary oxide layer in which the active elements Cr, Mn, Si, etc. in the steel are preferentially oxidized at the crystal grain boundaries. Can be made.

The types of carbides produced are mainly M ₃ C
And has high hardness. In the above, during the excessive carburizing treatment, a heat cycle in which cooling and heating are repeated can promote generation of carbides and spheroidization or acicularization, and at the same time miniaturization of crystal grains. Furthermore, after cooling once, quenching is performed at a quenching temperature of 1100 ° C., and the base is made of austenite, so that a wear-resistant material having excellent weatherability is obtained. Thus, the wear resistance provided with a hardened layer on the surface of the carburized hardened layer in which spherical fine carbides are dispersed and deposited,
It is possible to obtain wear resistant parts for a crusher having excellent impact resistance.

Further, the surface-hardened layer thus obtained has an effect of improving the wear resistance of the high-manganese cast steel in the early stage of use, and is also added to the effect of the work-hardened layer on the surface obtained during use. As compared with the conventional high manganese cast steel which is not subjected to surface treatment, it is possible to expect a great improvement in service life.

[0012]

EXAMPLES The present invention will be described below based on examples. After the steel having the chemical composition shown in Table 1 was melted, a crushing wear test piece was prepared. Then, the crushing wear test piece was subjected to carburizing treatment under the conditions shown in Table 2, and the results of the carburized layer hardness and the wear unit consumption by the crushing wear tester were obtained.

[0013]

[Table 1]

[0014]

[Table 2] Fig. 1 shows the thermal cycle of the carburizing treatment and the heat treatment for the sample A in Table 1.
Carburize at a carburizing temperature of 40 ° C. for 1 hour under a carbon potential of 1.5% or more, rapidly cool from that temperature to a low temperature of 500 ° C. or less, and then heat to the above temperature to perform carburizing repeatedly. In the example, the carburizing time was repeated 3 times to 3 hours and then cooled by gas fan cooling. Excess carburization at a high carburizing temperature is carried out by the above-mentioned operation, and the diffusion of C into the steel is remarkably promoted, and under repeated carburization, the formation of carbides and spherical or acicular formation in the surface-hardened layer is sequentially performed. Made progress. Subsequently, after quenching at a quenching temperature of 1100 ° C., an austenite base was obtained.

FIG. 2 shows the hardness distribution by Vickers hardness of the cross section of the sample after heat treatment for sample A in Table 2, and a higher hardness was obtained from the surface to a depth of 3.0 mm as compared with the matrix.

Similar to FIG. 2, FIG. 3 shows a photograph of the metal structure of Sample A after heat treatment for the surface layer portion and the core portion. It was found that the core had the austenite structure found in high-Mn steel, whereas the surface layer had finely divided and precipitated carbides, which was sufficient for excessive carburization.

In Table 2, the abrasion resistance test of Sample A of the present invention was carried out using a crushing abrasion tester. The crushing wear tester has a structure of an impact crusher, a crushing wear test piece as a hitting element, a peripheral speed of 30 m / s, a crushing gap of 15 mm, and a hard sandstone having a grain size of 20-05 as a reference material. 300 kg is subjected to a crushing treatment, and the wear basic unit (g / ton) is defined by using the weight difference of the crushing wear test pieces before and after the treatment. It indicates that the smaller the displayed numerical value, the higher the abrasion resistance.

The wear unit of sample A of the present invention was remarkably improved as compared with the conventional example in which excessive carburization was not performed, and high wear resistance was obtained. In this way, the wear life of the crusher wear resistant component of the present invention can be extended.

[0019]

As is apparent from the above examples, the present invention selects the composition of steel, performs excessive carburizing treatment at high temperature, and disperses and deposits hard spherical fine carbides in the carburized hardened layer on the surface. It is possible to provide an excellent wear resistant component for a crusher having a high spray resistance.

[Brief description of drawings]

FIG. 1 is an explanatory view of a heat cycle of carburizing treatment and heat treatment for a sample having a chemical component according to the present invention.

FIG. 2 is a hardness distribution curve of a sample cross section of the same sample.

FIG. 3 is a view showing a metallographic photograph of a surface layer portion and a core portion of the same sample.

Claims (2)

[Claims] 1. C: 1.0-1.6%, S by weight%
i: 0.3 to 1.2%, Mn: 10.0 to 27.0%,
Cr: 3.5% or less, Mo: 1.0% or less, V: 1.0
% Or less, with the balance being a chemical component consisting of Fe and impurities, the surface is subjected to excessive carburizing treatment in the temperature range of 950 to 1100 ° C. in an atmosphere having a carbon potential of 1.5% or more, and the carburized hardened layer is spherical or needle-shaped. A wear-resistant component for a crusher, characterized in that a hardened layer is provided on the material surface by disperse-precipitating finely divided fine carbides and subsequently quenching. 2. C: 1.0 to 1.6% by weight, S
i: 0.3 to 1.2%, Mn: 10.0 to 27.0%,
Cr: 3.5% or less, Mo: 1.0% or less, Ti: 1.
0% or less, V: 1.0% or less, the balance of which has a chemical composition of Fe and impurities, and the surface is subjected to excess carburization in a temperature range of 950 to 1100 ° C. in an atmosphere having a carbon potential of 1.5% or more. A wear-resistant component for a crusher, characterized in that a hardened layer is provided on the surface of the material by carrying out dispersion precipitation of spherical or needle-shaped fine carbide in the carburized hardened layer, and subsequently quenching.