阅读说明：本技术 一种大规格长寿命高碳轴承钢棒材及其制备方法 (Large-size long-life high-carbon bearing steel bar and preparation method thereof ) 是由 曹文全 王辉 王存宇 徐海峰 俞峰 梁剑雄 于 2021-08-16 设计创作，主要内容包括：本发明提供了一种大规格长寿命高碳轴承钢棒材及其制备方法,属于轴承钢领域。化学组成包括：0.93～1.05wt％C,1.20～1.80wt％Cr,0.02～0.15wt％Mo,0.02～0.15wt％Nb,0.02～0.15wt％V,0.02～0.15wt％Zr,其中Nb、V、Mo和Zr的总量要求0.05wt％≤Nb+V+Mo+Zr≤0.30wt％,余量的铁及其他不可避免的杂质。本发明通过将轴承钢进行Nb、V、Mo和Zr微合金化添加,大幅细化原始奥氏体组织与碳化物尺寸,实现本发明的大规格轴承钢的接触疲劳寿命的大幅提升,满足大型轴承对大规格轴承钢棒材质量与寿命要求。(The invention provides a large-size long-life high-carbon bearing steel bar and a preparation method thereof, belonging to the field of bearing steel. The chemical composition comprises: 0.93-1.05 wt% of C, 1.20-1.80 wt% of Cr, 0.02-0.15 wt% of Mo, 0.02-0.15 wt% of Nb, 0.02-0.15 wt% of V, 0.02-0.15 wt% of Zr, wherein the total amount of Nb, V, Mo and Zr is more than or equal to 0.05 wt% and less than or equal to Nb + V + Mo + Zr and less than or equal to 0.30 wt%, and the balance of iron and other inevitable impurities. According to the invention, the bearing steel is subjected to Nb, V, Mo and Zr microalloying addition, so that the original austenite structure and carbide size are greatly refined, the contact fatigue life of the large-specification bearing steel is greatly prolonged, and the requirements of large bearings on the quality and the service life of large-specification bearing steel bars are met.)

1. The utility model provides a big specification long-life high carbon bearing steel rod, its characterized in that, the chemical composition includes: 0.93-1.05 wt% of C, 1.20-1.80 wt% of Cr, 0.02-0.15 wt% of Mo, 0.02-0.15 wt% of Nb, 0.02-0.15 wt% of V, 0.02-0.15 wt% of Zr, wherein the total amount of Nb, V, Mo and Zr is more than or equal to 0.05 wt% and less than or equal to Nb + V + Mo + Zr and less than or equal to 0.30 wt%, and the balance of iron and other inevitable impurities.

2. The large-gauge long-life high-carbon bearing steel bar according to claim 1, wherein the chemical composition further comprises Si, Mn, Ni and Cu, the Si is 0.65 wt% or less, the Mn is 0.65 wt% or less, the Ni is 0.30 wt% or less, the Cu is 0.25 wt% or less, and the contents of Si, Mn, Ni and Cu are all not 0.

3. The large-size long-life high-carbon bearing steel bar material according to claim 1, wherein the diameter of the large-size long-life high-carbon bearing steel bar material is 61-150 mm, and the total thermal deformation of the bearing steel from cogging to finished product is not less than 4.

4. The method for preparing the large-specification long-life high-carbon bearing steel bar material as claimed in any one of claims 1 to 3, which is characterized by comprising the following steps:

smelting the raw materials to obtain a steel ingot;

carrying out homogenization treatment and bar forming on the steel ingot in sequence to obtain a bar;

and performing spheroidizing annealing, quenching and tempering on the bar in sequence to obtain the large-specification long-life high-carbon bearing steel bar.

5. The method according to claim 4, wherein the smelting is electroslag smelting, double vacuum smelting, external refining or vacuum induction furnace smelting.

6. The method according to claim 4, wherein the homogenization treatment is carried out at 1050 to 1250 ℃ for 2 to 30 hours.

7. The manufacturing method according to claim 4, wherein the spheroidizing annealing process includes: and (3) preserving the heat of the bar material at 800-860 ℃ for 0.5-12 hours, cooling to 680-740 ℃, preserving the heat for 0.5-12 hours, and finally air cooling to room temperature.

8. The preparation method according to claim 4, wherein the quenching temperature is 820-860 ℃, and the holding time is 0.10-1.0 hour; the cooling mode of quenching is oil quenching.

9. The preparation method according to claim 4, wherein the tempering temperature is 130-200 ℃, and the holding time is 0.5-3.5 hours; and the tempering cooling mode is air cooling.

10. The method according to claim 4, wherein the bar is shaped by hot forging or hot rolling, and the temperature of the hot forging or hot rolling is 1150-1200 ℃.

Technical Field

The invention relates to the technical field of bearing steel, in particular to a large-size long-life high-carbon bearing steel bar and a preparation method thereof.

Background

The high-carbon bearing steel is a main material for manufacturing the bearing, accounts for more than 80 percent of the output and sales volume of the bearing steel, and is an essential key base material for manufacturing the bearing. However, the fatigue life of the traditional bearing steel is greatly reduced along with the increase of the size specification of the bearing steel, and particularly after the specification of the bearing steel bar exceeds 60mm, the contact fatigue life of the bearing steel is reduced by times. In order to ensure the service life of the bearing to be prolonged and the bearing to be highly reliable, the metallurgical quality requirements are only put forward for small and medium-sized bars at home and abroad, and the quality and service life requirements cannot be ensured for bearing steel bars with the diameter of more than 60 mm.

Disclosure of Invention

In view of the above, the invention aims to provide a large-size long-life high-carbon bearing steel bar and a preparation method thereof. The high-carbon bearing steel has large specification and long fatigue life, and can meet the requirements of high-end equipment on large specification, long service life, high reliability and low cost bearing steel structure performance.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a large-size long-life high-carbon bearing steel bar, which comprises the following chemical components: 0.93-1.05 wt% of C, 1.20-1.80 wt% of Cr, 0.02-0.15 wt% of Mo, 0.02-0.15 wt% of Nb, 0.02-0.15 wt% of V, 0.02-0.15 wt% of Zr, wherein the total amount of Nb, V, Mo and Zr is more than or equal to 0.05 wt% and less than or equal to Nb + V + Mo + Zr and less than or equal to 0.30 wt%, and the balance of iron and other inevitable impurities.

Preferably, the chemical composition also comprises Si, Mn, Ni and Cu, wherein Si is less than or equal to 0.65 wt%, Mn is less than or equal to 0.65 wt%, Ni is less than or equal to 0.30 wt%, Cu is less than or equal to 0.25 wt%, and the contents of Si, Mn, Ni and Cu are all not less than 0.

Preferably, the diameter of the large-specification long-life high-carbon bearing steel bar is 61-150 mm, and the total thermal deformation of the bearing steel from cogging to finished products is not less than 4.

The invention also provides a preparation method of the large-specification long-life high-carbon bearing steel bar material, which comprises the following steps:

smelting the raw materials to obtain a steel ingot;

carrying out homogenization treatment and bar forming on the steel ingot in sequence to obtain a bar;

and performing spheroidizing annealing, quenching and tempering on the bar in sequence to obtain the large-specification long-life high-carbon bearing steel bar.

Preferably, the smelting mode is electroslag smelting, double vacuum smelting, external refining or vacuum induction furnace smelting.

Preferably, the temperature of the homogenization treatment is 1050-1250 ℃, and the heat preservation time is 2-30 hours.

Preferably, the spheroidizing annealing process includes: and (3) preserving the heat of the bar material at 800-860 ℃ for 0.5-12 hours, cooling to 680-740 ℃, preserving the heat for 0.5-12 hours, and finally air cooling to room temperature.

Preferably, the quenching temperature is 820-860 ℃, and the heat preservation time is 0.10-1.0 hour; the cooling mode of quenching is oil quenching.

Preferably, the tempering temperature is 130-200 ℃, and the heat preservation time is 0.5-3.5 hours; and the tempering cooling mode is air cooling.

Preferably, the bar is formed by hot forging or hot rolling, and the temperature of the hot forging or hot rolling is 1150-1200 ℃.

The invention provides a large-size long-life high-carbon bearing steel bar, which comprises the following chemical components: 0.93-1.05 wt% of C, 1.20-1.80 wt% of Cr, 0.02-0.15 wt% of Mo, 0.02-0.15 wt% of Nb, 0.02-0.15 wt% of V, 0.02-0.15 wt% of Zr, wherein the total amount of Nb, V, Mo and Zr is more than or equal to 0.05 wt% and less than or equal to Nb + V + Mo + Zr and less than or equal to 0.30 wt%, and the balance of iron and other inevitable impurities. According to the invention, the bearing steel is subjected to Nb, V, Mo and Zr microalloying addition, so that the original material is greatly refinedThe austenitic structure and the carbide size greatly improve the contact fatigue life of the large-specification bearing steel, and meet the requirements of the large-specification bearing steel bar on the quality and the service life. The results of the embodiments show that the bearing steel Nb, V, Mo and Zr are added in a microalloying manner, so that the contact fatigue life of the large-specification bearing steel with the diameter of 61-150 mm is greatly prolonged by 7.5-25 times, and particularly the contact fatigue life L of a bar with the diameter of 150mm under the stress of 4.5GPa after heat treatment is prolonged by 7.5-25 times₁₀≥5.0×10⁷Second, L of the steel bar of the traditional bearing₁₀≥0.20×10⁷The secondary height is 25 times higher, and the requirement of large-scale bearings on the quality and the service life of large-scale bearing steel bars is met, and the contact fatigue life of the large-scale bearings is longer than that of the traditional bearing steel GCr 15.

Drawings

FIG. 1 is a distribution diagram of the contact fatigue life weibull of the steels D60 and D150 of the present invention and the conventional steels C60 and C150 of the comparative steels.

Detailed Description

The invention provides a large-size long-life high-carbon bearing steel bar, which comprises the following chemical components: 0.93-1.05 wt% of C, 1.20-1.80 wt% of Cr, 0.02-0.15 wt% of Mo, 0.02-0.15 wt% of Nb, 0.02-0.15 wt% of V, 0.02-0.15 wt% of Zr, wherein the total amount of Nb, V, Mo and Zr is more than or equal to 0.05 wt% and less than or equal to Nb + V + Mo + Zr and less than or equal to 0.30 wt%, and the balance of iron and other inevitable impurities.

The large-size long-life high-carbon bearing steel bar provided by the invention comprises 0.93-1.05 wt% of C, preferably 0.97-1.01 wt%, and more preferably 1.00 wt%.

The large-size long-life high-carbon bearing steel bar provided by the invention comprises 1.20-1.80 wt% of Cr, preferably 1.45-1.50 wt%, and more preferably 1.50 wt%.

The large-size long-life high-carbon bearing steel bar provided by the invention comprises 0.05-0.15 wt% of Nb, preferably 0.05-0.09 wt%, and more preferably 0.09 wt%.

The large-size long-life high-carbon bearing steel bar provided by the invention comprises 0.05-0.15 wt% of Mo, preferably 0.05-0.09 wt%, and more preferably 0.06 wt%.

The large-size long-life high-carbon bearing steel bar provided by the invention comprises 0.05-0.15 wt% of V, preferably 0.05-0.09 wt%, and more preferably 0.06 wt%.

The large-size long-life high-carbon bearing steel bar provided by the invention comprises 0.05-0.15 wt% of Zr, preferably 0.05-0.09 wt%, and more preferably 0.06 wt%.

In the invention, the chemical composition preferably further comprises Si, Mn, Ni and Cu, wherein Si is less than or equal to 0.65 wt%, Mn is less than or equal to 0.65 wt%, Ni is less than or equal to 0.30 wt%, Cu is less than or equal to 0.25 wt%, and the contents of Si, Mn, Ni and Cu are all not less than 0.

The large-size long-life high-carbon bearing steel bar provided by the invention preferably comprises 0.30-0.34 wt% of Si, and more preferably 0.34 wt%.

The large-size long-life high-carbon bearing steel bar provided by the invention preferably comprises 0.40-0.44 wt% of Mn, and more preferably 0.44 wt%.

The large-size long-life high-carbon bearing steel bar provided by the invention preferably comprises 0.20-0.24 wt% of Ni, and more preferably 0.24 wt%.

The large-size long-life high-carbon bearing steel bar provided by the invention preferably comprises 0.20-0.24 wt% of Cu, and more preferably 0.24 wt%.

The large-size long-life high-carbon bearing steel bar material provided by the invention also comprises inevitable impurities, and the content of the inevitable impurities meets the requirement of GB 18254-2016.

In the invention, the diameter of the large-size long-life high-carbon bearing steel bar is preferably 61-150 mm, and the total thermal deformation of the bearing steel from cogging to finished product is preferably not less than 4.

The invention also provides a preparation method of the large-specification long-life high-carbon bearing steel bar material, which comprises the following steps:

smelting the raw materials to obtain a steel ingot;

carrying out homogenization treatment and bar forming on the steel ingot in sequence to obtain a bar;

and performing spheroidizing annealing, quenching and tempering on the bar in sequence to obtain the large-specification long-life high-carbon bearing steel bar.

The invention smelts the raw materials to obtain the steel ingot.

In the invention, the smelting mode is preferably electroslag smelting, double vacuum smelting, external refining or vacuum induction furnace smelting. The invention has no special requirements on the smelting process, and the method can be used for electroslag smelting, double vacuum smelting, external refining or vacuum induction furnace smelting which are well known in the field. In the present invention, the smelting is preferably applied to a converter, an electric furnace or an induction furnace. The invention has no special requirements on the types and sources of the preparation raw materials, and can meet the component requirements of steel ingots. The invention realizes that the oxygen content in the bearing steel is not higher than 20ppm and the size (DS) of large-particle inclusion is not more than 40 microns through smelting.

After the steel ingot is obtained, the steel ingot is subjected to homogenization treatment and bar forming in sequence to obtain the bar.

In the invention, the temperature of the homogenization treatment is preferably 1050-1250 ℃, more preferably 1150-1200 ℃, and the heat preservation time is preferably 2-30 hours, more preferably 10-15 hours.

After the homogenization treatment, the obtained blank is subjected to bar forming to obtain the bar. In the present invention, the bar is preferably formed by hot forging or hot rolling, and the temperature of the hot forging or hot rolling is preferably 1150 to 1200 ℃. In an embodiment of the invention, the diameter of the rod is 61mm, 120mm and 150 mm. The invention can obtain the refinement and homogenization of the matrix and the carbide through homogenization treatment. The invention preferably air cools the processed bar to room temperature before proceeding with the subsequent steps.

After the bar is obtained, the bar is sequentially subjected to spheroidizing annealing, quenching and tempering to obtain the large-size long-life high-carbon bearing steel bar.

In the present invention, the spheroidizing annealing process preferably includes: and (3) preserving the heat of the bar material at 800-860 ℃ for 0.5-12 hours, cooling to 680-740 ℃, preserving the heat for 0.5-12 hours, and finally air cooling to room temperature. The invention obtains uniform and fine carbide through spheroidizing annealing.

After the annealed bar is obtained, the annealed bar is quenched to obtain a quenched bar.

In the invention, the quenching temperature is preferably 820-860 ℃, more preferably 840 ℃, and the heat preservation time is preferably 0.10-1.0 hour, more preferably 0.5 hour; the cooling mode of the quenching is preferably oil quenching. The process of the oil quenching is not particularly required by the invention, and the oil quenching well known in the field can be adopted.

After the quenched bar is obtained, tempering the quenched bar to obtain the large-size long-life high-carbon bearing steel bar.

In the invention, the tempering temperature is preferably 130-200 ℃, more preferably 170 ℃, and the heat preservation time is preferably 0.5-3.5 hours, more preferably 3 hours; the cooling mode of tempering is preferably air cooling. The invention obtains superfine prior austenite structure and carbide particles by quenching and tempering, wherein the prior austenite grain size is not less than 8 grades.

In order to further illustrate the present invention, the large-scale long-life high-carbon bearing steel bar and the preparation method thereof provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.

Example 1

The steel of the invention is smelted by a laboratory through a vacuum induction furnace, a round ingot with the ingot shape of 500kg is cast, 6 furnaces of steel are smelted for forging rod-shaped samples, and the chemical components are shown in table 1. The D61, D120 and D150 steels are large-specification long-life high-carbon bearing steel bars, and the C061, C120 and C150 steels are designed according to the bearing steel composition of the national standard GB 18254-2016. The GCr15 steel ingot smelted by vacuum induction in the laboratory is subjected to homogenization treatment at 1200 ℃ for 12 hours, and is forged and cogging is carried out. Forging initial temperature is 1150 ℃, casting blanks with initial section size of 450mm are radially forged into round bars with section sizes of 61mm, 120mm and 150mm, and air cooling is carried out after forging. The round bar after forging is processed into contact fatigue samples after spheroidizing annealing treatment (heating to 800 ℃ and preserving heat for 5h, furnace cooling to 720 ℃ and keeping the temperature isothermal for 2h, air cooling to room temperature), quenching (oil cooling to room temperature after preserving heat for 0.5 h at 840 ℃) and low-temperature tempering treatment (air cooling to room temperature after preserving heat for 3 h at 170 ℃) are carried out on the samples) Finally, grain size and contact fatigue tests (contact fatigue test: a thrust piece test with the maximum Hertz stress of 4.5 GPa), the results are shown in Table 2, a weibull diagram of the contact fatigue life of the D061, D150, C061 and C150 steels is shown in FIG. 1, as can be seen from FIG. 1, the contact fatigue life of the bearing steel can be greatly prolonged by microalloying the bearing steel with Nb, Mo, V and Zr, and as can be seen from Table 2, the contact fatigue life L of D061₁₀≥7.5×10⁷Contact fatigue life L of D150₁₀≥5.0×10⁷Contact fatigue Life L of sub, C061₁₀≥1.0×10⁷Second, contact fatigue life L of C150₁₀≥0.20×10⁷Secondly, the contact fatigue life of the rod with the diameter of 61mm is improved by 7.5 times, the contact fatigue life of the rod with the diameter of 120mm is improved by 12 times, the contact fatigue life of the rod with the diameter of 150mm is improved by 25 times, and the D061-D150 steel has higher hardness, finer grain size and higher contact fatigue life than C061 and C150 steel.

TABLE 1 chemical composition of inventive steel and conventional steel (wt%)

In table 1, the elements not listed are iron and other inevitable impurity elements.

TABLE 2 grain size, hardness and contact fatigue Performance fatigue Properties of inventive steels and conventional steels

The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be construed as the protection scope of the present invention.