JPS60165352A - High frequency hardening steel - Google Patents

Abstract

PURPOSE:To attain to enhance durable life, impact fatique resistance and fretting fatigue property, by containing C, Si, Mn, Cr, O, P, S and Fe in a predetermined ratio. CONSTITUTION:High frequency hardening steel consists of, on a wt. basis, 0.4- 0.7% C, 0.5-1.5% Si, 0.7-1.1% Mn, 0.7-1.6% Cr, O<=0.0013% and the remainder of Fe and additionally contains P<=0.01% and S<=0.01%. This steel is excellent in durable life, impact fatique resistance and fretting fatique property and can be used in parts of a power transmission machine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an induction hardening steel that is used for power transmission machine parts such as rolling bearings, shafts, and gears and has excellent durability, impact fatigue, and flexoching/fatigue resistance.

In recent years, as automobiles have become lighter and cheaper,
Heat treatment work is also changing from conventional heating using heavy oil to high frequency heating, which can heat up to a predetermined temperature in a few seconds, and the conventional high carbon chromium bearing 1i'1sUJ2 lacks hardenability and causes quench cracking and distortion. There was a problem.

In addition, bearing members have changed from roller bearings to ball hair rings, and unit-type hair rings that omit the outer and inner rings have been used, and the conventional SUJ 2 lacks strength and suffers from impact fatigue under high surface pressure. The problem of low performance has arisen.

Against this background, requirements for power transmission machine parts such as rolling bearings and gears have become increasingly strict. There was a demand for the development of steel.

In response to such requirements, conventional SAE 1050.15
66゜0.5 C1,5Mn-0,3Cr steel, 0.6
C-0, 8MnO, 8Cr steel, etc. have been proposed and some are in practical use.

All of these steels have a lower ζC content than SUJ 2 and contain 0.8 to 1.50% Mn, allowing sieve frequency hardening and a tempering hardness of HRC60.
Although the above requirements are satisfied, the quench hardening depth is shallow,
``Durable life was short, and flexoching and fatigue resistance were also unsatisfactory.

The present invention has been made in view of the drawbacks of conventional steel,
As a result of various studies carried out by the present inventors, in order to obtain a durable life of SUJ' 2 or more, which is a high carbon steel 1-1 steel, induction hardening and tempering at 160°C are necessary.
We found that it is necessary to secure the above hardness and a hardening depth of 2 to 4 mm, and that for this purpose, the optimal amount of C in the matrix is about 0.6%, and that Si suppresses impact fatigue. It is an element that improves 30X 10” +
In order to obtain impact fatigue of tg fC or higher, it is necessary to contain 0.50% or more of Si, and to lower the upper limit of C content as much as possible.Furthermore, to improve fresoching and fatigue properties (indentation forming properties), it is necessary to contain Si of 0.50% or more. It has been found that it is necessary to contain 0.50% or more. Based on these findings, the present invention has been developed to provide a rolling material that can achieve a predetermined hardness and hardening depth through induction hardening, and has excellent durability, life expectancy, impact fatigue, and flexo fatigue resistance that can be reduced in weight and cost. The company succeeded in developing power transmission mechanical parts such as bearings, shafts, and gears.

The present invention will be explained in detail below.

The first invention steel is CO, 40-0,70% by weight, S
tO, 50-1.50%, MnO, 70-1.10%
, CrO, 70 to 1.60%, and OO, 0013% or less.The second invention steel has P and S contents of the first invention steel of 0.010% or less, respectively, in order to improve the rolling life. The third invention steel has a V O of 30% compared to the first invention steel.
Hereinafter, "B" rolling bearings containing one or two of NbO, 30% or less to further improve impact fatigue,
It has excellent properties as a power transmission mechanical part such as shafts and gears.

The reasons for limiting the composition of the steel of the present invention will be explained below.

C is the hardness kl p required for power transmission mechanical parts,
It is an element necessary to ensure C60 or higher, and therefore the lower limit is set to 0.40%. However, over 0.70% -ζ
The upper limit was set at 0.70% because if the content is low, durability life and impact fatigue will be reduced and quench cracking distortion will easily occur.

It is a main element in the present invention, which aims to improve durability, impact fatigue, and resoching/fatigue resistance as well as deoxidizing action. but,
If the content exceeds 1.50%, the transfer life characteristics deteriorate, so the upper limit was set at 1.50%.

Mn is an element necessary to improve hardenability and ensure a hardening depth of 2 mm or more.
% or more is required. However, even if a large amount of gold is added, the improvement in the effect is small, so the upper limit was set at i,io%.

Like Mn, Cr is an element that improves hardenability, and in order to obtain a hardening depth of 2111111 or more, it is necessary to contain 0.70% or more, and the lower limit thereof was set at 0.70%. However, if the content is too large, the carbide becomes hard and machinability deteriorates, so the upper limit was set at 1.60%.

0 is an element that combines with ζAl, Si, etc. in steel to form hard oxide-based inclusions and significantly deteriorates the transfer life characteristics.It is necessary to reduce its content as much as possible, and its upper limit was set at 0.0013%.

S and P are elements that deteriorate the transfer life characteristics, and their contents should be reduced as much as possible, and S and P were each set to 0.010%.

V, Nb forms carbonitrides and improves strength and toughness-U
There are elements. However, even if both V and Nb are contained in an amount exceeding 0.30%, the improvement in effectiveness is small, so the upper limit is set at 0.30%.
It was set at 30%.

Next, the characteristics of the steel of the present invention will be clarified in Examples by comparing it with conventional steel and comparative steel.

Table 1 shows the chemical composition of these test steels.

In Table 1, "ζΔ, B steel is conventional steel, A steel is 5UJ2
, B steel is SA[41566, c - E steel is comparative εI/
1 and 1.~M steels are steels of the present invention.

Table 3 shows the test steels A-M in Table 1, which were heated to
This figure shows the results of an investigation into the hardening depth, durability life, impact fatigue, and fresoching/fatigue properties for those tempered at 0°C for 1 hour.

The hardening depth indicates the distance from the surface where a hardness of °ζHRC60 or more was obtained through the quenching and tempering treatments, and the durability life was measured using a Mori thrust type durability life tester. Diameter 60φ x inner diameter 18φ x thickness 1
We made 10 specimens of 0 mm each, and tested 400 specimens of the car before testing.
kg, rotation speed 900 rpm, i'ra lubricant ゛ζ
Measurements were made using 60# spindle oil, and the ratio to the calculated life is shown.

For impact fatigue, a Matsuri type cyclic south impact fatigue tester was used to measure the length of 160mm x i415mm notch 2.5R.
A test piece was prepared and tested with an impact energy of 20 kgf-cm.

Regarding soresizing and fatigue resistance, tapered roller bearing L45449/10 (inner side) and 1M1
1749 /10 (Araku side) is combined to make the actual A
In fact, in the s5y state, there is a correlation between the acoustic value and the total indentation depth, and although there is some variation, they are almost proportional.

Regarding the hardening depth in Table 3, conventional steels A and B are 1.5f.
f1m.

1.8 mm, which is shallow at 2.0 mm or less, whereas all of the FM steels, which are the steels of the present invention, are hardened.

In addition, regarding the durability life, the conventional steels A and B have a shallow hardening depth of 2.0 mm or less as mentioned above, so the durability life is 1.8.2.0, and the comparative steels C and D For steel, ζ is as low as 0.3.0.4 due to the difference in the amount of Si. On the other hand, steels F to M, which are the steels of the present invention, are all 2.0 or more, and SUJ 2 , It has an excellent long life compared to S-1566.

Furthermore, the impact fatigue resistance is A, which is conventional steel.

4.0 to 7.0 XIOkgf・
In contrast, the inventive steel has a low river of 17
~M Qf4 all have a value of 30XIO kgf -cm or more due to the Si content of 0.50% or more, and have excellent impact fatigue properties.

Concerning flexo fatigue resistance and acoustic values, conventional steel and comparison net have low Si content as well as impact fatigue resistance, resulting in 16.8 to 20.3 p rn and 300 to 400 p rn.
Volt is large, whereas “ζ” is F-M, which is the steel of the present invention.
All steels have a small diameter of 10.5 μm or less and 225 Volt or less due to dust containing 0.50% or more of SiM, and SUJ 2. It has superior fresoching/fatigue properties and acoustic values compared to SAU 156B.

In this way, the steel of the present invention has found the optimum content of C15t, Mn, and Cr, and has also lowered the OL as much as possible, thereby ensuring a hardening depth of 2 mm or more with an HRC of 60 or higher, and SUJ 2. It has excellent durability, shock fatigue resistance, and flexo fatigue resistance of SAE 1566 or higher, and is suitable for use in power transmission machine parts such as rolling bearings, shafts, and gears, which can reduce weight and cost. It is an extremely important steel for industrial use.

Representative patent applicant

Claims (1)

[Claims] CO, 40-0.70%, Si
O, 50-1, 50%, Mn'0.70-1.10%,
CrO, 70-1, 60%. Steel for induction hardening, characterized in that it contains 0.0013% or less of oO, and the remainder consists of re and impurity elements. 2. CO, 40-0.70%, Si by weight
0.50-1.50%, Mn 0.70-1.10%,
CrO, 70-1.60%. 0 0.0013% or less, and further contains P O,0
A steel for induction hardening, characterized in that the content thereof is 10% or less, SO, 10% or less, and the remainder is Fe and impurity elements. 3. Weight ratio °ζ, CO, 40~0.79%, Si
O, 50-1.50%, Mn O, 70-1.10%
, CrO, 70-1, 60%. 0 Contains 0.0013% or less ζ, and further contains V O,3
A steel for induction hardening characterized by containing one or two of 0% or less, Nb O, and 30% or less, with the balance consisting of Fe and impurity elements.