JP2002542394A - Manufacturing method of rolling bearing steel - Google Patents

Abstract

  (57) [Summary] Steel, more particularly a method for producing rolling bearing steel, and rolling bearing parts produced by the method. Nominal 0.96 wt% C, 0.25 wt% Si to roll the steel directly after continuous casting or to roll immediately after heating without soaking heat treatment. , 0.85% by weight of Mn and 0.8% by weight of Cr. This kind of steel can advantageously be used for rolling production of bearing parts, more particularly bearing rings.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method for producing steel, comprising: -0.9 to 1.03% by weight of C; -0.15 to 0.35% by weight of Si; -Providing a steel containing 0.75 to 1.00 wt% Mn,-0.70 to 0.90 wt% Cr, and-residual Fe and impurities, said steel comprising continuous billet casting and Manufactured by subsequent rolling.

BACKGROUND OF THE INVENTION [0002] Bloom continuous casting is well known, and the definition of bloom casting is defined as casting, after two necessary heating steps, rolling a strand into a final sized bar or round bar, That is. Hengerer et al. 'Evaluation of the Continuous Cast
ing ASTM STP 1195, 1993 ', pp. 237-251.

In the prior art, as a method for reducing the cost for producing engineering steel, it has been proposed to produce this type of steel by continuous billet casting.
Paper by J. Lichtenstein, Brunel, Steel World Quarterly Vol. Issue 4, 25
See page 29.

[0004] The most commonly used rolled bearing steel ASTM A295 52100 has a C content of about 1% by weight.
It contains 25% by weight of Si, 0.35% by weight of Mn and 1.45% by weight of Cr and can be used for this purpose. However, soaking is required after continuous casting and before rolling. This is because, during solidification, primary carbides are generated due to segregation of the alloying elements C and Cr, and they remain in the steel unless reheat treatment and soaking heat treatment are performed. Segregation and primary carbides cause cavities after hot working and other defects in the final rolling bearing.

[0005] Such a soaking process is inevitably performed at a relatively high temperature for a relatively long time. This means that the benefits of continuous casting of ASTM A295 52100 steel are at least partially diminished by increased energy costs.
Generally, such a soaking heat treatment is not performed in a special atmosphere, and thus causes steel loss due to burnout. Due to these drawbacks, continuous casting of bearing steel has not fully realized its economic potential suggested.

[0006] GB 2294270A has 0.70 to. 093 wt% C, 0.15-. 0.50% by weight
Discloses a bearing steel comprising 0.5% to 1.10% by weight of Mn and 0.30% to 0.65% by weight of Cr. The Cr / C ratio is in the range of 0.4-0.7.

[0007] EP 0825270A1 contains 0.95 to 1.10% by weight of C, 0.15 to. It discloses a bearing metal comprising 0.70 wt% Si, up to 1.15 wt% Mn, 0.90 to 1.60 wt% Cr.

SUMMARY OF THE INVENTION [0008] In view of the fact that at present cost reduction can be achieved by using continuous casting, the present invention can avoid such a soaking heat treatment to eliminate segregation and therefore reduce quality. It is an object of the present invention to provide a method for producing steel that can sufficiently exhibit the possibility of cost reduction without significantly sacrificing.

According to the invention, this means that the steel has a nominally 0.96% by weight of C, 0.25% by weight of Si, 0.85% by weight of Mn, and 0% by weight. 0.8% by weight of Cr and the steel is rolled immediately after casting or rolled after casting and reheating without soaking heat treatment to give a Cr / 0.7 / 1.20 This is achieved in the manner described above that results in a C ratio.

Surprisingly, some steels with lower carbon and chromium contents and somewhat higher manganese contents show segregation and primary carbide formation as seen in ASTM A295 52100 steel. I knew it wasn't. This means that it is now possible to roll the steel immediately after continuous casting, or to carry out the rolling at a later stage, i.e. immediately after the heating of the billet, without soaking the steel without soaking. It means that rolling is possible.

It is believed that the segregation and primary carbide problems do not (generally) occur because the carbon content is somewhat lower and the chromium content is much lower. However, it should be understood that this is merely a theory unrelated to the validity of the appended claims.

According to a preferred embodiment of the present invention, the Cr / C ratio is. 75 and. Between 95.

According to another preferred embodiment, the Cr / C ratio is between 0.78 and 0.87.

Desirably, the steel is nominally 0.96% by weight C, 0.25% by weight Si, 0% by weight.
. It contains 85% by weight of Mn and 0.80% by weight of Cr. Such steel is
Also called ASTM A295 5195. The quenching of the steel can be carried out by either quenchless martensite quenching or peripheral (high frequency) quenching.

The suitability of the ASTM A295 5195 steel as a replacement for the ASTM A295 52100 steel is elucidated in FIGS. 1 and 2, which show martensite through-hardening and tempering reactions.

The steels described above can be used for all types of rolling bearings, but are preferably particularly suitable for bearings which are not subjected to severe loads. Particular application areas are those in which the service life of the bearing does not depend on the service life of the product to which it is mounted, ie, in which the service life of the bearing is much longer. A typical example is a rolling bearing of an electric motor. However, the invention is not limited to these uses, and those skilled in the art will be able to find other uses within the scope of the appended claims.

[Brief description of the drawings]

FIG. 1 is a diagram showing martensite through-hardening properties.

FIG. 2 is a diagram showing a tempering reaction.

[Procedural Amendment] Submission of translation of Article 34 Amendment

[Submission date] February 6, 2001 (2001.2.6)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Contents of correction]

[Claims]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16C 33/62 F16C 33/62 33/64 33/64 (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG) , KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR , LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW Reference) 3J101 AA01 BA10 BA70 DA03 DA20 EA02 FA44 GA24 4K042 AA22 BA13 CA06 DA01 DB01 DC05

Claims (8)

[Claims] 1. A method for producing steel, comprising: 0.9 to 1.03% by weight.
C, 0.15 to 0.35 wt% Si, 0.75 to 1.00 wt% Mn, 0.7
Comprising providing a steel containing from 0 to 0.90 wt% Cr and the balance Fe and impurities, wherein the steel is manufactured by continuous billet casting and subsequent rolling, wherein the steel comprises 0.25% Wt% Si, 0.85 wt% Mn, and 0.80
Weight percent Cr, the Cr / C ratio is between 0.7 and 1.20, and the steel comprises:
A method characterized by rolling immediately after casting or rolling after casting and reheating without soaking heat treatment. 2. The steel according to claim 1, wherein the steel comprises about 0.96% by weight of C.
The method described in. 3. The method according to claim 1, wherein the Cr / C ratio is between 0.75 and 0.95. 4. The method according to claim 1, wherein said steel comprises rolling bearing steel. 5. The method according to claim 4, wherein the steel part is quenched by a centerless martensite quenching or a peripheral induction quenching. 6. The method of claim 4, wherein the steel part has a through-hardened martensitic structure. 7. A rolling bearing element manufactured by a method according to one of the preceding claims. 8. A rolling bearing element according to claim 6, including a bearing ring.