阅读说明：本技术 一种主轴基体强韧化热处理方法 (Main shaft matrix strengthening and toughening heat treatment method ) 是由 尹卓君 李鼎福 于香华 *** 于 2020-07-23 设计创作，主要内容包括：本发明公开了一种主轴基体强韧化热处理方法,其步骤为：预处理—第一次普通淬火—第二次亚温淬火—第一次回火—第二次回火。主轴通过预处理,消除残余铸态及遗传组织影响,细化晶粒,消除应力；通过2次淬火特别是亚温淬火获得强度高的马氏体和韧性相的铁素体的混合组织；通过2次回火继续细化晶粒稳定组织,消除应力,获得以索氏体为主、细小块状铁素体为辅的回火组织,可以在不降低或略微降低材料的强度的情况下,明显的提高钢的塑性和韧性,尤其提高低温韧性。使34CrNi3Mo主轴的-45℃低温冲击值比普通方法提高30-50%,热处理一次合格率达到100%,提高了生产效率,降低了热处理成本。(The invention discloses a strengthening and toughening heat treatment method for a main shaft matrix, which comprises the following steps: pretreatment, primary common quenching, secondary sub-temperature quenching, primary tempering and secondary tempering. The main shaft eliminates the influence of residual cast state and genetic organization through pretreatment, refines crystal grains and eliminates stress; 2 times of quenching, particularly sub-temperature quenching, to obtain a mixed structure of martensite with high strength and ferrite with a tough phase; the grain stable structure is continuously refined through 2 times of tempering, the stress is eliminated, the tempered structure which takes sorbite as the main part and fine massive ferrite as the auxiliary part is obtained, and the plasticity and the toughness of the steel, especially the low-temperature toughness, can be obviously improved under the condition of not reducing or slightly reducing the strength of the material. The impact value of the 34CrNi3Mo main shaft at the low temperature of minus 45 ℃ is improved by 30 to 50 percent compared with the ordinary method, the first-time qualification rate of the heat treatment reaches 100 percent, the production efficiency is improved, and the heat treatment cost is reduced.)

1. A strengthening and toughening heat treatment method for a main shaft matrix comprises the following steps:

(1) firstly, pretreating test steel: the furnace temperature is less than 100 ℃ and is put into the furnace, the temperature rise speed is about 100 ℃/h, the temperature is raised to 870-plus-one 880 ℃ and is kept for 5 to 6 hours, and the mixture is taken out of the furnace and is cooled to the room temperature; then raising the temperature of the test steel to 650-670 ℃ at the temperature raising speed of 100 ℃/h or so for annealing for 5-6 hours, cooling the test steel to 500 ℃, taking the test steel out of the furnace and air-cooling the test steel to room temperature;

(2) and carrying out primary common quenching on the pretreated test steel:

the furnace temperature is less than 100 ℃ and is put into the furnace, the temperature rise speed is about 100 ℃/h, the temperature is raised to 870 plus 880 ℃ and is preserved for 5 to 6 hours, the quenching is carried out in HX-2000 organic quenching medium at the temperature of 18 to 23 ℃, and the medium is taken out and is cooled to the room temperature by air when the temperature is lower than 100 ℃;

(3) and carrying out secondary sub-temperature quenching on the test steel subjected to primary common quenching:

the furnace temperature is less than 100 ℃ and is put into the furnace, the temperature rise speed is about 100 ℃/h, the temperature is raised to 800-810 ℃, the temperature is kept for 5-6 hours, the quenching is carried out in HX-2000 organic quenching medium at the temperature of 18-23 ℃, and the medium is taken out and air-cooled to the room temperature when the temperature is lower than 100 ℃;

(4) and tempering the test steel subjected to the sub-temperature quenching for the first time:

the furnace temperature is less than 100 ℃ and the temperature is increased to about 540 ℃ and 550 ℃ at the temperature increasing speed of 100 ℃/h, the temperature is kept for 6 to 7 hours, and the mixture is taken out of the furnace and cooled in air;

(5) and carrying out secondary tempering on the test steel subjected to the sub-temperature quenching:

the furnace temperature is less than 100 ℃ and the temperature is increased to 560 ℃ and 570 ℃ at the temperature rising speed of 100 ℃/h or so, the temperature is kept for 6 to 7 hours, and the mixture is taken out of the furnace and cooled in air.

Technical Field

The invention relates to a strengthening and toughening heat treatment method for a main shaft matrix, in particular to a strengthening and toughening heat treatment method for a 34CrNi3Mo main shaft matrix, and belongs to the technical field of metal heat treatment.

Background

34CrNi3Mo is a medium alloy steel material commonly used by the top drive main shaft of national oil drilling and production equipment in high and cold regions such as North America, Russia and the like, has good mechanical properties, particularly excellent low-temperature impact property, and is commented by users. At present, the lowest temperature requirement of low-temperature impact required by users in the industry of the material is-45 ℃, the impact value of a V-shaped notch is not lower than 54J, and the situation that the low-temperature impact value at-45 ℃ is unqualified frequently occurs in the heat treatment actual production. Through a large number of tests and analysis summaries, a new heat treatment process scheme is adopted, so that the V-notch impact value of the material at the temperature of minus 45 ℃ is improved by at least 30% -50%. The innovation of the scheme is that the alloy is subjected to pretreatment before quenching, common quenching is carried out for 1 time in the quenching stage, then sub-temperature quenching is carried out for 2 times, a quenching liquid stirring device is manufactured in the quenching process, the cooling intensity is adjustable, and tempering treatment is carried out for 2 times finally. The purpose of pretreatment is to eliminate residual cast state and genetic organization, refine crystal grains stably and eliminate stress; the purpose of the sub-temperature quenching is to obtain a mixed structure of martensite with high strength and ferrite with a toughness phase, and the mixed structure can be refined by 2 times of high-temperature tempering under the condition of not reducing or slightly reducing the strength of the material, so that the stress is eliminated, the plasticity and the toughness of the steel are obviously improved, and particularly the low-temperature toughness is improved. The heat treatment process scheme is a combined application scheme of a series of heat treatment methods, and has the defects that the sequence cannot be changed, otherwise, the effect is greatly reduced, and the required low-temperature performance cannot be obtained.

Disclosure of Invention

The technical scheme adopted by the invention for solving the technical problems is as follows: a method for strengthening and toughening heat treatment of a main shaft matrix takes a 34CrNi3Mo main shaft as an example, and comprises the following steps:

1. firstly, pretreatment is carried out on test steel:

the furnace temperature is less than 100 ℃ and is put into the furnace, the temperature rise speed is about 100 ℃/h, the temperature is raised to 870-plus-one 880 ℃ and is kept for 5 to 6 hours, and the mixture is taken out of the furnace and is cooled to the room temperature; then raising the temperature of the test steel to 650-670 ℃ at the temperature raising speed of 100 ℃/h or so for annealing for 5-6 hours, cooling the test steel to 500 ℃, taking the test steel out of the furnace, and cooling the test steel to room temperature.

2. Carrying out primary common quenching on the pretreated test steel:

the furnace temperature is less than 100 ℃ and is put into the furnace, the temperature rise speed is about 100 ℃/h, the temperature is raised to 870-880 ℃, the temperature is preserved for 5 to 6 hours, the quenching is carried out in HX-2000 organic quenching medium at the temperature of 18 to 23 ℃, and the medium is taken out and air-cooled to the room temperature at the temperature lower than 100 ℃.

3. Carrying out secondary sub-temperature quenching on the test steel subjected to primary common quenching:

the furnace temperature is less than 100 ℃ and is put into the furnace, the temperature rise speed is about 100 ℃/h, the temperature is raised to 800-810 ℃, the temperature is kept for 5-6 hours, the quenching is carried out in HX-2000 organic quenching medium at the temperature of 18-23 ℃, and the medium is taken out and air-cooled to the room temperature at the temperature of less than 100 ℃.

4. The test steel subjected to the sub-temperature quenching is subjected to first tempering:

the furnace temperature is less than 100 ℃, the furnace is put into, the temperature rise speed is about 100 ℃/h, the temperature is raised to 540-550 ℃, the temperature is kept for 6 to 7 hours, and the furnace is taken out for air cooling.

5. And (3) performing secondary tempering on the test steel subjected to the sub-temperature quenching:

the furnace temperature is less than 100 ℃ and the temperature is increased to 560 ℃ and 570 ℃ at the temperature rising speed of 100 ℃/h or so, the temperature is kept for 6 to 7 hours, and the mixture is taken out of the furnace and cooled in air.

The invention has the beneficial effects that: the main shaft of 34CrNi3Mo eliminates the influence of residual cast state and genetic structure through pretreatment, refines grains and eliminates stress; 2 times of quenching, particularly sub-temperature quenching, to obtain a mixed structure of martensite with high strength and ferrite with a tough phase; the grain stable structure is continuously refined through 2 times of tempering, the stress is eliminated, the tempered structure which takes sorbite as the main part and fine massive ferrite as the auxiliary part is obtained, and the plasticity and the toughness of the steel, especially the low-temperature toughness, can be obviously improved under the condition of not reducing or slightly reducing the strength of the material. The impact value of the 34CrNi3Mo main shaft at the low temperature of minus 45 ℃ is improved by 30 to 50 percent compared with the ordinary method, the first-time qualification rate of the heat treatment reaches 100 percent, the production efficiency is improved, and the heat treatment cost is reduced.

Drawings

FIG. 1 shows the results of metallographic examination of sample No. 1 of the examples.

Fig. 2 is a metallographic examination result of sample No. 2 of the example.

FIG. 3 shows the results of metallographic examination of sample No. 3 of the example.

Detailed Description

A method for strengthening and toughening heat treatment of a main shaft matrix takes a 34CrNi3Mo main shaft as an example, and comprises the following steps:

1. firstly, pretreatment is carried out on test steel:

the furnace temperature is less than 100 ℃ and is put into the furnace, the temperature rise speed is about 100 ℃/h, the temperature is raised to 870-plus-one 880 ℃ and is kept for 5 to 6 hours, and the mixture is taken out of the furnace and is cooled to the room temperature; then raising the temperature of the test steel to 650-670 ℃ at the temperature raising speed of 100 ℃/h or so for annealing for 5-6 hours, cooling the test steel to 500 ℃, taking the test steel out of the furnace, and cooling the test steel to room temperature.

2. Carrying out primary common quenching on the pretreated test steel:

the furnace temperature is less than 100 ℃ and is put into the furnace, the temperature rise speed is about 100 ℃/h, the temperature is raised to 870-880 ℃, the temperature is preserved for 5 to 6 hours, the quenching is carried out in HX-2000 organic quenching medium at the temperature of 18 to 23 ℃, and the medium is taken out and air-cooled to the room temperature at the temperature lower than 100 ℃.

3. Carrying out secondary sub-temperature quenching on the test steel subjected to primary common quenching:

the furnace temperature is less than 100 ℃ and is put into the furnace, the temperature rise speed is about 100 ℃/h, the temperature is raised to 800-810 ℃, the temperature is kept for 5-6 hours, the quenching is carried out in HX-2000 organic quenching medium at the temperature of 18-23 ℃, and the medium is taken out and air-cooled to the room temperature at the temperature of less than 100 ℃.

4. The test steel subjected to the sub-temperature quenching is subjected to first tempering:

the furnace temperature is less than 100 ℃, the furnace is put into, the temperature rise speed is about 100 ℃/h, the temperature is raised to 540-550 ℃, the temperature is kept for 6 to 7 hours, and the furnace is taken out for air cooling.

5. And (3) performing secondary tempering on the test steel subjected to the sub-temperature quenching:

the furnace temperature is less than 100 ℃ and the temperature is increased to 560 ℃ and 570 ℃ at the temperature rising speed of 100 ℃/h or so, the temperature is kept for 6 to 7 hours, and the mixture is taken out of the furnace and cooled in air.

Experimental data:

the chemical compositions of the first 34CrNi3Mo main shaft test steel are shown in Table 1:

TABLE 134 CrNi3Mo chemical composition of Main shaft test Steel (mass fraction%)

Second, performance test results

Third, metallographic examination result

The metallographic examination result of sample No. 1 is shown in fig. 1;

the metallographic examination result of sample No. 2 is shown in fig. 2;

the metallographic examination of sample No. 3 gave the results shown in fig. 3.

Fourthly, conclusion:

the strengthening and toughening method of the 34CrNi3Mo spindle matrix achieves and exceeds the technical standard requirement through the implementation of a series of heat treatment process methods, particularly obviously improves the low-temperature impact index, and proves that the process scheme can be applied to the practical production application of the strengthening and toughening of the 34CrNi3Mo spindle matrix.