JPH111749A - Steel for induction hardening, excellent in bending fatigue strength and rolling fatigue strength - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel for induction hardening, capable of providing machine parts, such as gear, shaft, and uniform velocity joint for automobile, excellent in bending fatigue characteristic and rolling fatigue characteristic by means of induction hardening. SOLUTION: This steel is composed of a linear or bar-shaped rolled steel stock. In the longitudinal cross section passing through the axis of this rolled steel stock, the number of multiple inclusions of oxide and sulfide of >=10 μm average grain size, existing in the inspection area of 100 mm<2> containing, as a center line, a virtual line parallel to the axis and apart from the axis by 1/4.D (where D means the diameter of the rolled stock), is regulated to <=20 pieces. This steel can produce excellent bending fatigue strength and rolling fatigue strength by being subjected to induction hardening.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel material subjected to a surface hardening treatment, and particularly to a steel material subjected to induction hardening to obtain excellent bending fatigue characteristics and rolling fatigue characteristics as mechanical parts such as gears, shafts and constant velocity joints of automobiles and the like. The present invention relates to induction hardening steel which provides a component with the same.

[0002]

2. Description of the Related Art Induction quenching has higher energy efficiency than conventional hardening methods such as carburizing and carbonitriding, and is easy to perform in-line heat treatment to reduce the intermediate stock of parts. It is widely used in the manufacture of various machine parts such as those for construction machines, for example, gears, shafts, pins, and the like.

[0003] Since these mechanical parts are subjected to severe bending force, rotational force, frictional force and the like during use, they are required to have high bending fatigue characteristics and rolling fatigue characteristics. It is known that bending fatigue properties and rolling fatigue properties of parts are considerably inferior to those of mechanical parts which have been subjected to conventional carburizing or carbonitriding and quenching.
Therefore, as measures to improve the fatigue property deficiency, the rolling fatigue property is improved by increasing the hardness and tempering softening resistance of the steel material (Japanese Patent Application Laid-Open No. 60-169547), and the induction hardening conditions are optimized (Japanese Patent Application Publication No. No. 60898), improvement of bending fatigue characteristics by improving hardenability of steel material (JP-A-5-2396)
02) has been proposed.

On the other hand, recently, there has been a strong demand for lighter weight and higher output of automobiles, especially in view of reduction of fuel consumption and exhaust gas. In order to meet these demands, mechanical parts are required to have higher strength. The load applied per unit weight tends to increase more and more, and the fact is that it is no longer possible to cope with such means. In particular, even if it is modified by the above method, when it is applied to an application where a high load is applied, it causes fatigue fracture starting from coarse inclusions, and bending fatigue characteristics and rolling fatigue that can meet the demands of consumers. The characteristics are no longer guaranteed.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object to achieve excellent bending fatigue characteristics and rolling fatigue characteristics by induction hardening. It is intended to provide a simple induction hardening steel.

[0006]

The induction hardening steel according to the present invention, which can solve the above-mentioned problems, is made of a rolled steel rod or rod and has a longitudinal section passing through the axis of the rolled steel. , Parallel to the axis and 1/4 · D from the axis
(D represents the diameter of the rolled material) The number of composite inclusions having an average particle size of 10 μm or more, which are composed of oxides and sulfides, and exist in a test area of 100 mm ² including a separated virtual line as a center line The steel for induction hardening has 20 or less pieces and has improved bending fatigue strength and rolling fatigue strength.

[0007] The preferred composition of the steel for induction hardening that provides the above-mentioned inclusion characteristics and strength characteristics is as follows: C: more than 0.3% and 0.7% or less Mn: 0.3 to 2.5% Si: 2% P: 0.03% or less (including 0%) S: 0.10% or less (including 0%) Al: 0.015 to 0.05% O: 0.002% or less (Including 0%) Remaining: Fe and inevitable impurities satisfying the requirements, or in addition to these, Cu: 0.03 to 1.0% Ni: 2% or less (excluding 0%) Cr : 2% or less (excluding 0%) Mo: 2% or less (excluding 0%) Use of a steel material containing at least one element selected from the group consisting of: Or V as another element: 1% or less (excluding 0%) Nb: 0.1% or less (excluding 0%) Ti: 0.1% or less (excluding 0%) When at least one element selected from the group consisting of: Ca: 0.0005 to 0.01% Pb: 0.3% or less (excluding 0%) Te: 0.1% or less (excluding 0%) Bi: 0.1% or less (excluding 0%) Zr: 0.1% or less (excluding 0%) When at least one element selected from the group consisting of: Machinability can be further enhanced without impairing dynamic fatigue characteristics or the like, or B: 0.01% or less (not including 0%) as another element and N: 0.006% or less (Including 0%)
It is preferable that the content be suppressed to as high as it is possible to further improve the induction hardening property and to improve the grain boundary strength.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the reasons for limiting the size and number of inclusions which are important components in the present invention will be described in detail. The steel for induction hardening according to the present invention is characterized in that, in a longitudinal section passing through an axis of a rolled steel material obtained by rolling a steel material into a line or a rod, the steel is parallel to the axis and 1/4 · D (D is a Of the inclusions present per 100 mm ^{2 of the} test area including the imaginary line as the center line, indicating the diameter of the steel material, 20 composite inclusions composed of oxides and sulfides and having an average particle size of 10 μm or more are included. In the following, it is more preferable that the number is 15 or less. By defining the number of such inclusions, it is possible to stably exhibit excellent bending fatigue characteristics and rolling fatigue characteristics.

This requirement is a requirement reached as a result of repeated studies on the effects of inclusions on bending fatigue characteristics and rolling fatigue characteristics after induction hardening from various angles. And sulfide-based composite inclusions (hereinafter sometimes referred to as oxide-sulfide-based composite inclusions), the coarse composite inclusions having an average particle size of 10 μm or more are minimized as much as possible after induction hardening. It is based on the finding that bending fatigue characteristics and rolling fatigue characteristics are extremely excellent.

FIG. 1 shows, from many experimental data, an average particle diameter of 10 mm ² existing in the above-mentioned area of 100 mm ^2.
A graph showing the effects of the number of composite inclusions of μm or more on the bending fatigue strength and rolling fatigue strength after induction hardening (however, the induction hardening conditions are 150 k output).
w, frequency: 20 kHz, work coil moving speed: 21
mm / sec).

As is apparent from FIG.
If the number of coarse composite inclusions of 0 μm or more is 20 or less in the test area, a high level of bending fatigue strength and rolling fatigue strength after induction hardening is exhibited. Fatigue strength rapidly decreases.

As described above, in the present invention, by defining the number of coarse oxide / sulfide-based composite inclusions having a specific size or more in a specific test area, excellent bending fatigue characteristics and rolling characteristics can be obtained by induction hardening. It is characterized in that it can express dynamic fatigue characteristics.The number of such inclusions is, for example, using a steel material having a component composition as described below, and as a temperature condition during casting or rolling, for example, The slab cooling rate from the solidification point to about 1000 ° C. at the time is about 3 ° C. or more, and the heating temperature during rolling is about 1200 ° C. or less,
By controlling the rolling reduction to about 30% or more and the finish rolling temperature to about 1100 ° C. or less, it is preferable because the number thereof can be further reduced. Next, the reason for defining the chemical components of the steel material preferably used in the present invention will be described.

C: more than 0.3% and 0.7% or less C is a useful element for securing core hardness as a strengthening element and for giving surface hardness by induction hardening. Below, it is difficult to obtain a sufficient surface height, and it is difficult to obtain satisfactory fatigue characteristics. But 0.7%
If the content is excessive, the toughness of the core portion will be poor, the machinability and the cold forgeability will also deteriorate, and furthermore, quenching cracks will easily occur during induction hardening. A more preferred lower limit of the C content is 0.45%, and a more preferred upper limit is 0.55%.

Si: 2% or less (including 0%) Si not only functions effectively as a deoxidizing agent at the time of melting, but also acts as a strengthening element and contributes to the improvement of core hardness, but is too much. In addition to deteriorating the toughness of the core portion, it also has an adverse effect on machinability and cold forgeability, so the content should be kept at most 2% or less, preferably 1% or less.

Mn: 0.3 to 2.5% Mn not only functions effectively as a deoxidizing agent at the time of melting, but also increases the strength and toughness of the core, further increases the induction hardenability and improves the fatigue strength. It is a contributing element and must be contained in an amount of 0.3% or more in order to effectively exert those effects.
However, if the content is too large, the material becomes too hard and the machinability and the cold forgeability deteriorate, so the content should be suppressed to 2.5% or less. A more preferable range of Mn is 0.3 to 2.0%.

Al: 0.015 to 0.05% Al also effectively acts as a deoxidizing component at the time of melting, and also has the effect of suppressing the growth of austenite crystal grains during heating and increasing the toughness. Such an effect is effectively exerted by containing Al in an amount of 0.015% or more. However, since these effects are saturated at about 0.05%,
Further addition is not only meaningless, but also large amounts of oxide-based inclusions are generated to increase the amount of coarse composite inclusions,
Since the bending fatigue characteristics and the rolling fatigue characteristics are adversely affected, the content is preferably suppressed to 0.05% or less, more preferably 0.04% or less.

S: 0.1% or less (including 0%) S effectively acts as a machinability improving component, but if contained in a large amount, coarse oxide-based and sulfide-based composite inclusions may be formed. Since it is formed in a large amount and adversely affects the bending fatigue characteristics and the rolling fatigue characteristics, and particularly remarkably reduces the strength of the cross grain in the working direction, it should be suppressed to 0.1% or less. A more preferred upper limit of S is 0.03%, and may be substantially zero%.

P: 0.03% or less (including 0%) Since P causes grain boundary segregation and lowers grain boundary strength to cause embrittlement, P is 0.03% or less, more preferably 0.02% or less.
% Or less.

O: 0.002% or less (including 0%) O _2, which becomes a nucleus of composite inclusions when the content of O is large,
Since a large amount of coarse oxide inclusions such as O ₃ and SiO ₂ are generated to increase the amount of coarse composite inclusions and degrade bending fatigue characteristics and rolling fatigue characteristics, 0.002% or less, more preferably 0% or less. .0015% or less.

The remaining components of the steel material preferably used in the present invention are Fe and unavoidable impurities. If necessary, the following elements may be added in appropriate amounts to further improve the properties of the steel for induction hardening. It can be further improved.

Cu: 0.03 to 1.0% Ni: 2% or less (excluding 0%) Cr: 2% or less (excluding 0%) Mo: 2% or less (excluding 0%) At least one element selected from the group consisting of: These elements are the same in that they contribute to the improvement of induction hardenability, and their actions are described in detail below. That is, Cu is an element that contributes to the improvement of hardenability and also effectively acts to improve the corrosion resistance, and the effect thereof should be about 0.03% or more, more preferably about 0.2% or more. Effectively demonstrated by However, if the content is too large, hot cracking is likely to occur, impairing hot workability. Therefore, the content should be suppressed to 1.0% or less, more preferably 0.6% or less. Ni is also an element that effectively enhances the induction hardenability and improves the toughness. Such an effect is effectively exhibited by containing about 0.2% or more, but the effect is saturated at about 2%. However, if the content is more than that, quenching cracks are likely to occur during induction hardening, so the content should be suppressed to 2% or less.

Cr also contributes to the improvement of induction hardenability, and furthermore, acts as a carbide forming element to generate fine carbides, increase softening resistance, and contribute to improvement of rolling fatigue characteristics. Such an effect is effectively exhibited by containing about 0.3% or more. However, when the content is more than 2%, the hardness of the material is reduced and the bending fatigue property and toughness are adversely affected. Therefore, it must be kept below 2%. Mo also contributes to the improvement of the induction hardenability and also to the formation of carbides to increase the softening resistance and to improve the rolling fatigue characteristics.
Further, it has the effect of refining austenite crystal grains and increasing the compressive residual stress in the surface layer. Such an effect is effectively exhibited by containing 0.05% or more, but if the content is too large, the machinability will be adversely affected. Therefore, the content is suppressed to 2% or less, more preferably 1% or less. Is good.

V: 1% or less (excluding 0%) Nb: 0.1% or less (excluding 0%) Ti: 0.1% or less (excluding 0%) At least one element These elements contribute to refinement of crystal grains and improvement in toughness.
It is the same element in that
It is on the street. That is, V generates carbides and makes crystal grains fine.
And has the effect of increasing the stability of carbides.
Increases softening resistance and contributes to improvement of rolling fatigue characteristics. like this
Effect by adding about 0.2% or more.
It is effective, but if the content becomes too large,
A_Three , A ₁ Transformation point is greatly reduced and core is not sufficiently gamma-converted
It becomes difficult to bake and becomes insufficient in hardness,
Should be kept below 1%. Nb is also carbonized like V
And carbonitride-forming element that refines crystal grains toughness
Bending fatigue characteristics by contributing to improvement and by improving surface hardness
Is an element that is effective in improving steel, and its effect is about 0.01%
Effectively exhibited by containing the above. However
The effect is saturated at about 0.1%,
Is only economically disadvantageous. Ti also has fine grains
Effective element for thinning and also effective for deoxidation and denitrification of steel
Act on. When B is contained at the same time, N
To make the effect of B described later more effective.
It also has an effect. However, if too much, hard
Large amounts of inclusions cause poor bending fatigue and rolling fatigue characteristics
0.1% or less, more preferably 0.05%
%.

Ca: 0.0005 to 0.01% Pb: 0.3% or less (excluding 0%) Te: 0.1% or less (excluding 0%) Bi: 0.1% or less (0 %) Zr: 0.1% or less (excluding 0%) Zr: at least one selected from the group consisting of the following: All of these elements are the same in that they contribute to the improvement of machinability. . In addition, Ca, Te, and Zr also have an effect of spheroidizing inclusions to improve anisotropy. That is, Ca
Has an effect of generating sulfide-based inclusions together with Mn, spheroidizing the inclusions, improving anisotropy, and enhancing machinability without deteriorating toughness or bending fatigue properties. The effect is about 0.0005% or more, more preferably 0.000%.
Effectively exhibited by containing at least 8%. However, if it is too large, a large amount of coarse composite inclusions in which sulfide-based inclusions are bound around coarse CaS or oxide-based inclusions and deteriorates the bending fatigue properties. Preferably, it should be suppressed to 0.005% or less. Pb also effectively acts as a machinability improving element, but if it is too much, the bending fatigue characteristics and the pitting life are significantly deteriorated, so it should be suppressed to 0.3% or less, more preferably 0.1% or less.

Te forms Mn-Te and coexists around MnS, suppresses deformation of MnS during hot rolling, promotes spheroidization of MnS, and does not deteriorate the toughness and bending fatigue characteristics of steel. Has the effect of enhancing machinability. However, if it exceeds 0.1%, the bending fatigue characteristics are rather deteriorated due to an increase in the amount of non-metallic inclusions, so the content must be suppressed to 0.1% or less. Bi also contributes to the improvement of machinability, but if the content is too large, it has an adverse effect on bending fatigue characteristics and rolling fatigue characteristics, so it should be suppressed to 0.1% or less. Zr also suppresses the deformation of MnS during hot rolling, contributes to the spheroidization of MnS and effectively acts to improve anisotropy, and also enhances machinability without deteriorating toughness or bending fatigue properties. However, if the content is too large, the amount of non-metallic inclusions such as ZrO ₂ increases and the bending fatigue characteristics are adversely deteriorated. Therefore, the content is preferably suppressed to 0.1% or less.

B: 0.01% or less (excluding 0%) and N: 0.006% or less (including 0%) B is an extremely small amount to enhance induction hardenability and increase grain boundary strength. The effect is particularly effective when the content is 0.0005% or more. However, since the effect is saturated at 0.01%, further addition is useless and is preferably suppressed to about 0.005% or less. In addition, N combines with B to form BN and impairs the effect of improving the hardenability of B, so it should be suppressed to 0.006% or less. The conditions for induction hardening using the steel for induction hardening of the present invention are not particularly limited.

Thus, according to the present invention, by specifying the component composition of the steel material, and by specifying the number of the oxide / sulfide-based composite inclusions having a coarse average particle size and having a specific cross section as a test surface, It has become possible to provide a steel for induction hardening that exhibits excellent bending fatigue characteristics and rolling fatigue characteristics by induction hardening.

When manufacturing parts such as gears using the steel for induction hardening of the present invention, after processing into a part shape according to a conventional method, induction hardening is performed according to a conventional method, and shot peening or the like is performed as necessary. And harden the surface.

[0029]

EXAMPLES Next, the structure and operation and effect of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples, but conforms to the spirit of the preceding and following examples. Of course, the present invention can be implemented with modifications as far as possible, and all of them are included in the technical scope of the present invention.

Example 1 A steel material having the composition shown in Table 1 was used, and the cooling rate during casting was changed to change the size and amount of the composite inclusion.
o. In Nos. 1 to 13, 15, and 17, a 150 kg vacuum melting furnace was used for melting and casting, and then forged into a round bar having a diameter of 65 mm. In No. 14, it was melted and cast using a 150 kg atmosphere furnace, and then forged into a round bar having a diameter of 65 mm. In No. 16, it was cast into a 5-ton ingot and then rolled into a round bar having a diameter of 65 mm.

[0031]

[Table 1]

Thereafter, in order to examine the non-metallic inclusions in each round bar, as shown in FIG. 2, in a vertical section including the axis of each round bar, the diameter (vertical section) is parallel to the axis and from the axis. (Width of surface) A sample having a width of 20 mm and a length of 30 mm is cut out from a position including a virtual line 1 / 4.D apart from 65 mm as a center line, and the composition and size of nonmetallic inclusions present in the cross section are measured using EPMA. Well, I checked the number. The measurement was performed in a continuous automatic operation at a magnification of 400 times, and the composition, size, and number of all nonmetallic inclusions existing per 100 mm ^{2 of the} test area were measured, and the average particle diameter [(major axis + minor axis) was obtained. / 2] was determined to be 10 μm or more.

Further, for each forged / rolled material having a diameter of 65 mm,
Solution treatment of “1200 ° C. × 2 hours → air cooling” and “93
After performing a normalizing process of “0 ° C. × 2 hours → air cooling”, an Ono-type rotating bending fatigue test piece (smooth) was prepared from a position of 1/4 · D of each round bar. The diameter of each round bar is 6
A disk having a thickness of 0 mm and a thickness of 5 mm was cut out to produce a thrust-type rotating fatigue test piece. After that, output 150KW, frequency 20KHZ, work coil moving speed 21mm / sec
Induction hardening under the conditions of
Tempering treatment of “2 hours → air cooling” was performed. Then, the rotating bending test piece was subjected to the test as it was. For the rolling fatigue test, after performing lapping, the contact pressure was 527 kg.
A rolling fatigue test was performed under the condition of f / mm ² . Table 2 shows the results. For the rolling fatigue test results, L ₁₀ (1
0% cumulative failure rate).

[0034]

[Table 2]

From Tables 1 and 2, it can be analyzed as follows. No. Examples 1 to 13 satisfy all of the requirements of the present invention, and have an appropriate steel material composition and an average particle diameter of 10 μm.
Since the number of the oxide / sulfide-based composite inclusions is 20 or less, excellent results are obtained in both bending fatigue strength and rolling fatigue strength.

On the other hand, no. Nos. 14 to 17 are comparative examples lacking the prescribed requirements of the present invention. In No. 14, since the smelting was performed in an atmospheric furnace, the O content of the steel material was large, and the average particle size of the oxide-sulfide composite inclusions was large and the number thereof was large, and the bending fatigue strength and the rolling fatigue life were low. Both are bad. No. In No. 16, since the cooling rate during casting is low, there are many coarse oxide / sulfide-based composite inclusions, the bending fatigue strength is low, and the rolling fatigue life is short. No. No. 17, coarse composite inclusions increase due to the large S content in the steel material,
Again, the bending fatigue strength and rolling fatigue life are poor.

Example 2 A steel material having a chemical composition shown in Table 3 was melted in a 150 kg vacuum melting furnace, cast, and then forged into a round bar having a diameter of 65 mm.

[0038]

[Table 3]

Thereafter, in order to examine the non-metallic inclusions in each round bar, as shown in FIG. 2, in a vertical section including the axis of each round bar, an imaginary line 1 / 4.D away from the axis. A sample having a width of 20 mm × 30 mm was cut out from a position including as a center line, and the composition, size, and number of nonmetallic inclusions present in the cross section were examined by EPMA in the same manner as in Example 1. The measurement was performed in a continuous automatic operation at a magnification of 400 times, and the composition, size, and number of all nonmetallic inclusions existing per 100 mm ^{2 of the} test area were measured, and the average particle diameter [(major axis + minor axis) was obtained. / 2] is 10 μm or more, and the number of coarse oxide / sulfide-based composite inclusions was determined.

Thereafter, a quenching process of “875 ° C. × 1 hour → 60 ° C. oil cooling” is performed, and “575 ° C. × 1 hour → water cooling”.
After tempering, 1/4 ・ D from the axis of the round bar
Ono-type rotating bending fatigue test pieces (smooth) were prepared from a remote position. In addition, the diameter is 60 mm x
A disk having a thickness of 5 mm was cut out to produce a thrust-type rotating fatigue test piece. Then, as in the first embodiment, the output 15
0KW, frequency 20KHZ, work coil moving speed 21
An induction hardening treatment was performed under the condition of mm / sec, and a tempering treatment of “150 ° C. × 2 hours → air cooling” was further performed. Then, the rotating bending test piece was subjected to the test as it was.
For the rolling fatigue test, lapping was performed, and the rolling fatigue test was performed under the conditions of a surface pressure of 527 kgf / mm ² . Table 4 shows the results. The rolling fatigue test results were evaluated using L ₁₀ (10% cumulative failure rate).

[0041]

[Table 4]

From Tables 3 and 4, it can be considered as follows. No. Nos. 18 to 21 are examples satisfying the requirements of the present invention. The number of oxide-sulfide composite inclusions having an appropriate steel material composition and an average particle diameter of 10 μm or more is 20 or less, and the flexural fatigue strength is 18 to 21. Excellent results were obtained for both the rolling fatigue strength and the rolling fatigue strength. Although the rolling fatigue life of the present example is slightly inferior to the normalized steel of Example 1, it is superior to the comparative steel and is at a level without any problem.

On the other hand, no. Nos. 22 and 23 are comparative examples lacking the prescribed requirements of the present invention. No. 22, since the smelting was performed in an atmospheric furnace, the O content of the steel material was large, and as a result, the size and the number of the oxide-based inclusions were large,
As a result, there are many coarse oxide / sulfide-based composite inclusions, and both the bending fatigue strength and the rolling fatigue life are poor. Also N
o. In No. 23, since the S content in the steel material is large, the number of coarse composite inclusions increases, and the bending fatigue strength and rolling fatigue life are also poor.

[0044]

The present invention is configured as described above, and by specifying the number of oxide / sulfide-based composite inclusions of a characteristic size having a specific cross section as a surface to be inspected, is improved by induction hardening. It has become possible to provide an induction hardening steel which exhibits bending fatigue strength and rolling fatigue life. In addition, the steel for induction hardening having such characteristics uses a steel material having a component composition as defined in claims 2 to 6, and uses a vacuum furnace or the like to suppress the incorporation of oxygen during smelting, and to perform casting. It can be easily obtained by taking measures such as increasing the cooling rate of the slab below the solidification temperature at the time.

[Brief description of the drawings]

FIG. 1 Oxide-sulfide composite inclusions (average particle size 10μ)
m or more) and the relationship between the bending fatigue strength and the rolling fatigue life.

FIG. 2 is an explanatory diagram showing a measurement region of the number of oxide / sulfide-based composite inclusions.

Claims (6)

[Claims] 1. In a longitudinal section passing through an axis of the rolled steel material, the cross section is made of a linear or bar-shaped rolled steel material, and is 1/4 · D (D is the diameter of the rolled material) from the axis. Represents)
Inspection area 100 mm ² including the imaginary line as the center line
Average particle size of oxide and sulfide based on
Induction hardening steel excellent in bending fatigue strength and rolling fatigue strength, characterized in that the number of composite inclusions of 0 μm or more is 20 or less. 2. C: more than 0.3% (hereinafter, means mass% unless otherwise specified) more than 0.7% or less Mn: 0.3 to 2.5% Si: 2% or less (including 0%) P: 0.03% or less (including 0%) S: 0.1% or less (including 0%) Al: 0.015 to 0.05% O: 0.002% or less (including 0%) Remainder The steel for induction hardening according to claim 1, comprising a steel material satisfying the requirements of: Fe and unavoidable impurities. 3. The steel material contains Cu: 0.03 to 1.0% Ni: 2% or less (excluding 0%) Cr: 2% or less (excluding 0%) Mo: 2% The steel for induction hardening according to claim 2, wherein the steel contains at least one element selected from the group consisting of the following (not including 0%). 4. The steel material further includes V: 1% or less (not including 0%) Nb: 0.1% or less (not including 0%) Ti: 0.1% or less (0% or less) The steel for induction hardening according to claim 2 or 3, wherein the steel contains at least one element selected from the group consisting of: 5. The steel material further contains Ca: 0.0005 to 0.01% Pb: 0.3% or less (excluding 0%) Te: 0.1% or less (excluding 0%) 5. Bi: 0.1% or less (excluding 0%) Zr: 0.1% or less (excluding 0%) Zr: At least one element selected from the group consisting of: Induction hardening steel according to any of the above. 6. The steel material further contains B: 0.0 as another element.
Including 1% or less (excluding 0%), N: 0.006%
The steel for induction hardening according to any one of claims 2 to 5, which is the following (including 0%).