High-carbon-chromium stainless bearing steel 102Cr17Mo structure heat treatment method

Abstract

The invention discloses a high-carbon chromium stainless bearing steel 102Cr17Mo structure heat treatment method, which consists of four parts of high-temperature normalizing, annealing, quenching and tempering structure homogenization, and specifically comprises the following steps of: firstly, carrying out 920 DEG C high-temperature homogenization treatment, then carrying out part softening treatment through a spheroidizing annealing process, meanwhile, blocking carbides, reducing the sizes of the carbides, and carrying out high-temperature annealing, so that the high-carbon chromium stainless bearing steel 102Cr17Mo is obtained. According to the method, the steps are simple, operation is convenient and fast, the grain size of a finished product is remarkably improved, and therefore the service life of the bearing is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of bearing steel treatment, and in particular to a heat treatment method for the structure of high-carbon chromium stainless bearing steel 102Cr17Mo. Background Art

[0002] Under the background of the rapid development of modern industry, the operating speed and load of mechanical equipment continue to rise. As a key component, the working conditions of bearings are becoming increasingly severe. Customers' requirements for bearing performance indicators have reached an unprecedented level. They not only clearly require the bearing DN value to be greater than 2 million to significantly improve the equipment operation efficiency, but also urgently need to extend the bearing service life and reduce the maintenance cost. In addition, in fields with strict environmental requirements such as food processing and medical equipment, the bearing also needs to have excellent corrosion resistance; in precision instruments and high-end equipment, low-noise characteristics are also indispensable. Currently, the industry mainly tries to meet the above requirements by improving the heat treatment method to enhance the material performance. However, limited by the process principle and equipment accuracy, the existing heat treatment technology is unable to meet the diverse and strict requirements of customers and is difficult to achieve performance breakthroughs in multiple dimensions such as increasing the DN value, extending the life, achieving corrosion resistance and low noise. Summary of the Invention

[0003] Aiming at the deficiencies of the existing technology, the present invention provides a heat treatment method for the structure of high-carbon chromium stainless bearing steel 102Cr17Mo. The steps are simple and the operation is convenient. The finished product grain size is significantly improved, thereby realizing the improvement of the bearing life.

[0004] To achieve the above object, the present invention provides a heat treatment method for the structure of high-carbon chromium stainless bearing steel 102Cr17Mo, including the following steps.

[0005] Step 1: Heat the raw material to 690 ± 10 °C and hold for 3 h, then cool to room temperature at a rate of 50 - 60 °C / h.

[0006] Step 2: Heat to 920 ± 10 °C and hold for 2 h, then heat to 1130 ± 10 °C and hold for 5 h, and then cool to room temperature.

[0007] Step 3: Heat to 690 ± 10 °C and hold for 3 h, then cool to room temperature at a rate of 50 - 60 °C / h.

[0008] Step 4: Austenitizing treatment, heat to 920 ± 10 °C and hold for 2 h, then heat to 1100 °C and hold for 2 h.

[0009] Step 5: Isothermal spheroidizing annealing, heat to 870 ± 10 °C and hold for 9 h, reduce to 760 ± 10 °C at a rate of 50 - 60 °C / h and hold for 8 h, then reduce to 550 ± 10 °C at a rate of 50 - 60 °C / h and hold for 4 h, and then take out of the furnace and cool.

[0010] Step 6: Isothermal spheroidizing annealing, followed by turning and then quenching and tempering.

[0011] As a further setting of the present invention, step 1 is repeated 3 times.

[0012] As a further setting of the present invention, step 2 further includes spreading the processed material flat and then blowing air to cool it to room temperature.

[0013] As a further setting of the present invention, in step 4, after holding at 920 °C, it is heated to 1100 °C at a rate of 240 °C / h for holding.

[0014] The beneficial effects of such a setting are as follows: With such a setting, multiple preheating and homogenization treatments are carried out by heating the raw material to 690 ± 10 °C for holding for 3 hours, then cooling to room temperature at a cooling rate of 50 - 60 °C / h, and repeating 3 times, initially homogenizing the internal composition and structure of the steel, reducing the initial stress, and laying a solid foundation for subsequent carbide dissolution. Subsequently, in the high-temperature homogenization and rapid cooling stage, the steel is first heated to 920 ± 10 °C for holding for 2 hours, then heated to 1130 ± 10 °C for holding for 5 hours. After the treatment, the steel is spread out and cooled to room temperature by blowing air. The long-time high-temperature holding promotes the full dissolution and diffusion of carbides. The operation of spreading and blowing air during cooling not only prevents tissue defects caused by uneven cooling but also fixes the high-temperature uniform structure, inhibits the abnormal precipitation of carbides, further homogenizes the steel structure, generates uniform spheroidal pearlite, with a hardness of 210 HBW, greatly improving the machining performance. Immediately following, in the secondary homogenization and stress elimination step, the steel is heated to 690 ± 10 °C again for holding for 3 hours and cooled to room temperature at a rate of 50 - 60 °C / h, further homogenizing the structure, reducing the cold working residual stress, improving the dimensional stability of the steel, reducing subsequent processing deformation, and also creating conditions for grain refinement and carbide dissolution. In the austenitizing treatment stage, it is first heated to 920 ± 10 °C for holding for 2 hours, and then heated to 1100 °C at a rapid heating rate of 240 °C / h for holding for 2 hours, effectively inhibiting grain growth and controlling the grain size in an ultra-fine state above grade 9, significantly improving the strength and toughness of the steel. In the isothermal spheroidizing annealing step, it is first heated to 870 ± 10 °C for holding for 9 hours, cooled to 760 ± 10 °C at a rate of 50 - 60 °C / h for holding for 8 hours, and then cooled to 550 ± 10 °C for holding for 4 hours before being taken out for cooling, fully reducing the residual stress, homogenizing the structure, refining the grains, achieving the uniform spheroidization of carbides and the dissolution of large carbides, and improving the wear resistance and fatigue performance of the steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is the process flow chart of the embodiment of the present invention;

[0016] Figure 2It is a magnified view of a partial structure using the existing process;

[0017] Figure 3 It is a schematic diagram of the grain structure using the existing process;

[0018] Figure 4 It is a magnified view of a partial structure of an embodiment of the present invention;

[0019] Figure 5 It is a schematic diagram of the grain structure of an embodiment of the present invention. Detailed implementation manners

[0020] The implementation example of the heat treatment method for the 102Cr17Mo high-carbon chromium stainless bearing steel of the present invention is as Figure 1 , Figure 4 and Figure 5 shown:

[0021] It includes the following steps,

[0022] Step 1: Heat the raw material to 690 ± 10 °C and hold for 3 h, then cool it to room temperature at a rate of 50 - 60 °C / h;

[0023] Step 2: Heat it to 920 ± 10 °C and hold for 2 h, then heat it to 1130 ± 10 °C and hold for 5 h, and then cool it to room temperature;

[0024] Step 3: Heat it to 690 ± 10 °C and hold for 3 h, then cool it to room temperature at a rate of 50 - 60 °C / h;

[0025] Step 4: Austenitization treatment, heat it to 920 ± 10 °C and hold for 2 h, then heat it to 1100 °C and hold for 2 h;

[0026] Step 5: Isothermal spheroidizing annealing, heat it to 870 ± 10 °C and hold for 9 h, reduce the temperature to 760 ± 10 °C at a rate of 50 - 60 °C / h and hold for 8 h, then reduce the temperature to 550 ± 10 °C at a rate of 50 - 60 °C / h, hold for 4 h, and then take it out of the furnace and cool it;

[0027] Step 6: Isothermal spheroidizing annealing, perform turning and forming, and then quenching and tempering treatment.

[0028] As a further setting of this embodiment, step 1 is repeated 3 times.

[0029] As a further setting of this embodiment, in step 2, the processed material is laid flat and then cooled to room temperature by blowing air.

[0030] As a further setting of this embodiment, in step 4, after holding at 920 °C, it is heated to 1100 °C at a rate of 240 °C / h for holding.

[0031] The comparison between the present embodiment and the existing process is shown in the following table:

[0032]

[0033]

[0034] The above examples are only one of the preferred specific examples of the present invention. All ordinary changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention are included in the protection scope of the present invention.

Claims

1. A heat treatment method for the structure of high-carbon chromium stainless bearing steel 102Cr17Mo, characterized in that: It includes the following steps: Step 1: Heat the raw materials to 690 ± 10 °C and hold for 3 h, then cool to room temperature at a rate of 50 - 60 °C / h; Step 2: Heat to 920 ± 10 °C and hold for 2 h, then heat to 1130 ± 10 °C and hold for 5 h, and cool to room temperature; Step 3: Heat to 690 ± 10 °C and hold for 3 h, then cool to room temperature at a rate of 50 - 60 °C / h; Step 4: Austenitizing treatment, heat to 920 ± 10 °C and hold for 2 h, then heat to 1100 °C and hold for 2 h; Step 5: Isothermal spheroidizing annealing, heat to 870 ± 10 °C and hold for 9 h, reduce to 760 ± 10 °C at a rate of 50 - 60 °C / h and hold for 8 h, then reduce to 550 ± 10 °C at a rate of 50 - 60 °C / h, hold for 4 h, and take out of the furnace and cool; Step 6: Isothermal spheroidizing annealing, perform turning and forming, and then quenching and tempering treatment.

2. The heat treatment method for the structure of high-carbon chromium stainless bearing steel 102Cr17Mo according to claim 1, characterized in that: The first step is repeated 3 times.

3. The heat treatment method for the structure of the high-carbon chromium stainless bearing steel 102Cr17Mo according to claim 1, characterized in that: In the second step, it also includes laying the treated material flat and then blowing air to cool it to room temperature.

4. The heat treatment method for the structure of the high-carbon chromium stainless bearing steel 102Cr17Mo according to claim 1, characterized in that: In the fourth step, after holding at 920 °C, heat to 1100 °C at a rate of 240 °C / h for holding.

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