CN114350903A - Quenching cooling method of 5CrNiMoV module - Google Patents

Abstract

The invention provides a quenching cooling method of a 5CrNiMoV module, which can effectively improve the quenching effect of the 5CrNiMoV large module, reduce the hardness difference of a core surface and reduce the quenching cracking risk. The quenching cooling method of the 5CrNiMoV module is characterized by comprising the following steps of: 1) heat treatment of a quenching furnace: controlling the effective thickness of the 5CrNiMoV module to be 150-300 mm, heating to 650 ℃ along with the furnace, keeping the temperature for 0.4-0.6min/mm, continuously heating to 840-880 ℃, and keeping the temperature for 1.0-1.5 min/mm; 2) combined cooling treatment: and after the furnace is taken out, air cooling, water cooling and oil cooling are sequentially carried out, wherein the air cooling speed is 50-70 ℃/min, the air cooling time is 1-2 min/100mm, the water cooling speed is 100-150 ℃/min, the water cooling time is 1-2 min/100mm, the oil cooling speed is 15-25 ℃/min, and the oil cooling time is 10-15 min/100 mm.

Description

Quenching cooling method of 5CrNiMoV module

Technical Field

The invention relates to the technical field of quenching and cooling of alloy steel, in particular to a quenching and cooling method of a 5CrNiMoV module.

Background

The hardenability of the 5CrNiMoV material is relatively poor, the quenching size effect is sensitive, when the effective thickness of the module is more than 150mm, the problems of different degrees exist in the conventional quenching cooling technology, the risk of brine or water quenching cracking is high, the oil cooling rate is insufficient, the difference between the hardness of the core and the hardness of the surface is large, the service life of the module is shortened, and the problem is a general problem which is currently encountered by low-alloy die steel with poor hardenability.

The chemical composition of 5CrNiMoV is shown in the following table.

Disclosure of Invention

The invention provides a quenching cooling method of a 5CrNiMoV module, which can effectively improve the quenching effect of the 5CrNiMoV large module, reduce the hardness difference of a core surface and reduce the quenching cracking risk.

The technical scheme is that the quenching cooling method of the 5CrNiMoV module is characterized by comprising the following steps of:

1) heat treatment of a quenching furnace: controlling the effective thickness of the 5CrNiMoV module to be 150-300 mm, heating to 650 ℃ along with the furnace, keeping the temperature for 0.4-0.6min/mm, continuously heating to 840-880 ℃, and keeping the temperature for 1.0-1.5 min/mm;

2) combined cooling treatment: and after the furnace is taken out, air cooling, water cooling and oil cooling are sequentially carried out, wherein the air cooling speed is 50-70 ℃/min, the air cooling time is 1-2 min/100mm, the water cooling speed is 100-150 ℃/min, the water cooling time is 1-2 min/100mm, the oil cooling speed is 15-25 ℃/min, and the oil cooling time is 10-15 min/100 mm.

Compared with the prior art, the quenching cooling method provided by the invention has the advantages that after quenching heat preservation is finished, a combined cooling mode of air cooling, water cooling and oil cooling is adopted, the cooling speed of different media is regulated and controlled, the difference of the surface hardness of the 5CrNiMoV module core with the effective thickness of 150-300 mm can be reduced, and the quenching cracking risk is reduced.

Detailed Description

The 5CrNiMoV modules used in examples 1-3 and comparative example 1 below were purchased from Sichuan Liuhe forging Co., Ltd and had dimensions of φ 150X300 mm.

Example 1

The 5CrNiMoV module is subjected to heat treatment, including quenching and tempering.

1. Quenching:

1) loading the module into a furnace, heating to 650 ℃ along with the furnace, keeping the temperature for 60min, and continuously heating to 840 ℃ and keeping the temperature for 3.5 h;

2) air cooling for 1.5 minutes, the average cooling rate of the module is 70 ℃/min, water cooling for 2 minutes is carried out, the average cooling rate of the module is 150 ℃/min, oil cooling is 15 minutes, and the average cooling area speed of the module is 24 ℃/min;

2. tempering: keeping the temperature at 580 ℃ for 5 hours, and cooling the mixture to room temperature in air.

Example 2

The 5CrNiMoV module is subjected to heat treatment, including quenching and tempering.

1. Quenching:

1) loading the module into a furnace, heating to 650 ℃ along with the furnace, keeping the temperature for 60min, and continuously heating to 840 ℃ and keeping the temperature for 3.5 h;

2) air cooling for 2 minutes, the average cooling rate of the module is 50 ℃/min, water cooling is carried out for 3 minutes, the average cooling rate of the module is 100 ℃/min, oil cooling is carried out for 22.5 minutes, and the average cooling area speed of the module is 16 ℃/min;

2. tempering: keeping the temperature at 580 ℃ for 5 hours, and cooling the mixture to room temperature in air.

Example 3

The 5CrNiMoV module is subjected to heat treatment, including quenching and tempering.

1. Quenching:

1) charging the module into a furnace, heating to 650 ℃ along with the furnace, keeping the temperature for 60min, continuously heating to 880 ℃, keeping the temperature for 3.5h,

2) air cooling for 2 minutes, the average cooling rate of the module is 50 ℃/min, water cooling is carried out for 3 minutes, the average cooling rate of the module is 100 ℃/min, oil cooling is carried out for 22.5 minutes, and the average cooling area speed of the module is 16 ℃/min; then keeping the temperature at 580 ℃ for 5 hours and cooling the mixture in air.

2. Tempering: keeping the temperature at 580 ℃ for 5 hours, and cooling the mixture to room temperature in air.

Comparative example 1

It is different from the embodiment 1 in that air cooling and water cooling are not adopted, the oil cooling time is 32 minutes, the average cooling zone speed of the module is 24 ℃/min,

the surface and the core of the module after heat treatment in the above examples were subjected to hardness testing. The specific test results are shown in the following table:

the difference of the core surface hardness of the inventive examples 1-3 is within 5, while the difference of the core surface hardness of the comparative example 1 is 28 degrees, which shows that the inventive method can greatly reduce the difference of the core surface hardness. Meanwhile, according to observation, the combined cooling mode of three media of air cooling, water cooling and oil cooling is adopted, so that the cooling speed is improved, the cracking phenomenon is avoided, and the quenching cracking risk can be reduced.

Claims (1)

1. The quenching cooling method of the 5CrNiMoV module is characterized by comprising the following steps of:

1) heat treatment of a quenching furnace: controlling the effective thickness of the 5CrNiMoV module to be 150-300 mm, heating to 650 ℃ along with the furnace, keeping the temperature for 0.4-0.6min/mm, continuously heating to 840-880 ℃, and keeping the temperature for 1.0-1.5 min/mm;

2) combined cooling treatment: and after the furnace is taken out, air cooling, water cooling and oil cooling are sequentially carried out, wherein the air cooling speed is 50-70 ℃/min, the air cooling time is 1-2 min/100mm, the water cooling speed is 100-150 ℃/min, the water cooling time is 1-2 min/100mm, the oil cooling speed is 15-25 ℃/min, and the oil cooling time is 10-15 min/100 mm.