CN110964890A - Heat treatment method of high-hardness high-impact-toughness alloy material - Google Patents

Heat treatment method of high-hardness high-impact-toughness alloy material Download PDF

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CN110964890A
CN110964890A CN201911342800.0A CN201911342800A CN110964890A CN 110964890 A CN110964890 A CN 110964890A CN 201911342800 A CN201911342800 A CN 201911342800A CN 110964890 A CN110964890 A CN 110964890A
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treatment
impact
hardness
temperature
quenching
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赵飞
刘源
彭承银
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Guizhou University
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Guizhou University
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/007—Heat treatment of ferrous alloys containing Co
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/78—Combined heat-treatments not provided for above
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

The invention discloses a heat treatment method of a high-hardness high-impact-toughness alloy material. After austenitizing treatment, putting the material into quenching oil for quenching treatment; after quenching treatment, putting the material into an isothermal molten salt bath medium for heat preservation and distribution treatment; and (3) after the distribution treatment, putting the material into room temperature water or oil for cooling treatment to obtain the product. The invention can improve the hardness of the material and the impact toughness of the material, and the material is used for manufacturing the hob of the shield machine, thereby effectively prolonging the service life of rolling.

Description

Heat treatment method of high-hardness high-impact-toughness alloy material
Technical Field
The invention relates to the technical field of metal heat treatment processes, in particular to a heat treatment method of a high-hardness high-impact-toughness alloy material.
Background
The application of the shield machine in the construction of urban subways, railway roads, energy transportation pipelines and other heavy projects is more and more extensive. The shield machine has the advantages of high construction speed, high quality, low labor intensity, economy, environmental protection and the like. The hob in the shield machine is used as a part directly contacted and acted with rocks and soil, is equivalent to teeth of the shield machine, and is an important structural part for realizing the excavation operation of the shield machine. The shield machine cutter works in an environment with underground soil, rocks and gravels accompanied by humidity, the service environment is harsh, and the main failure modes of the shield machine cutter comprise fracture, abrasion, deformation and the like. In order to ensure the safe and efficient operation of the shield machine, the requirements on the toughness, particularly the hardness and the toughness of the hob material of the shield machine are high.
At present, the main heat treatment process of the alloy material for manufacturing the hob mostly adopts quenching and twice high-temperature tempering, and the material has higher hardness and wear resistance by precipitating fine carbides to generate secondary hardening. However, in these processes, the toughness and hardness of the material are not well combined, so that the technical index requirements (hardness is 56HRC or more and impact value is 20J or more) of high-quality hob cutters are difficult to achieve, and the service life of the hob cutters is short. Therefore, the research on a method for improving the hardness and the toughness of the hob material has important significance.
Disclosure of Invention
The invention aims to provide a heat treatment method for an alloy material with high hardness and high impact toughness. The invention can improve the hardness of the material and the impact toughness of the material, and the material is used for manufacturing the hob of the shield machine, thereby effectively prolonging the service life of rolling.
The technical scheme of the invention is as follows: a heat treatment method of high-hardness high-impact-toughness alloy material comprises the steps of austenitizing the material, and then putting the austenitized material into quenching oil for quenching treatment; after quenching treatment, putting the material into an isothermal molten salt bath medium for heat preservation and distribution treatment; and (3) after the distribution treatment, putting the material into room temperature water or oil for cooling treatment to obtain the product.
In the heat treatment method of the high-hardness high-impact-toughness alloy material, the austenitizing treatment is as follows: and (3) preserving the heat of the material for 30-60 min at the heat preservation temperature of 900-1000 ℃.
In the heat treatment method for the high-hardness and high-impact-toughness alloy material, the holding temperature during austenitizing treatment is 950 ℃.
In the heat treatment method of the high-hardness high-impact-toughness alloy material, the quenching treatment comprises the following steps: and keeping the temperature in quenching oil at the temperature of 50-150 ℃ for 15-40 s.
In the heat treatment method of the high-hardness high-impact-toughness alloy material, the quenching treatment comprises the following steps: when the thickness of the section of the material is less than 50mm, keeping the temperature in quenching oil at the temperature of 50-150 ℃ for 15-30 s at constant temperature; when the section thickness of the material is more than 50mm, keeping the temperature for 30-40 s in quenching oil at the constant temperature of 50-150 ℃.
In the heat treatment method of the alloy material with high hardness and high impact toughness, the distribution treatment comprises the following steps: and preserving the heat for 1-3 h in an isothermal molten salt bath medium at 270-320 ℃.
In the heat treatment method of the alloy material with high hardness and high impact toughness, the heat preservation time of the distribution treatment is 2 hours.
In the heat treatment method of the high-hardness high-impact-toughness alloy material, the salt bath medium is KNO3With NaNO2A mixture of (a).
In the heat treatment method of the alloy material with high hardness and high impact toughness, the KNO3With NaNO2The weight ratio of the mixture was 1: 1.
Compared with the prior art, the method has the advantages that the material is austenitized and then quenched, so that the material obtains a certain proportion of martensite structure and simultaneously retains a part of metastable austenite structure; and then putting the material into an isothermal molten salt bath medium for heat preservation and distribution treatment, diffusing and distributing supersaturated carbon in the martensite to the attenuated austenite which is not transformed, increasing the carbon content in the attenuated austenite, reducing the Ms point, increasing the residual austenite content of the structure retained to room temperature, and preserving the heat of the material above the Ms point for a certain time to decompose the metastable austenite for bainite transformation. The method ensures the hardness of the material, and simultaneously leads the material to have residual austenite and low-temperature bainite, thereby improving the impact toughness of the material. The final material structure obtained by the heat treatment of the invention is as follows: most of martensite, low-temperature bainite, partial residual austenite and fine carbide, and the complex phase structure not only ensures the high hardness of the material, but also ensures the material to obtain better toughness. Ultimately extending the roll-to service life of the material. In addition, the invention can control the martensite content in the material structure by controlling the temperature and isothermal time of primary quenching, thereby not only using martensite to ensure the hardness of the material, but also obtaining better ductility and toughness by low-temperature bainite and residual austenite. Compared with the traditional heat treatment process, the method has the advantages that the process is simpler and easier to control, and the heat treatment cost is lower.
In order to more intuitively embody the beneficial effects of the present invention, the inventors carried out the following experimental comparisons:
the weight percentages of the components of the heat-treated material are shown in Table 1
TABLE 1
Figure BDA0002332075200000031
The materials prepared by the components are divided into two groups and respectively subjected to the following heat treatment processes:
the traditional heat treatment process comprises the following steps: the material is insulated for 30min at 950 ℃, and is insulated for 2h for one tempering at 500 ℃ after oil cooling quenching at room temperature, and is insulated for 2h for a second tempering at 480 ℃. Performance of the material after heat treatment: hardness 46HRC, impact energy 22J.
The heat treatment process of the invention comprises the following steps: the material is kept at 950 ℃ for 30min, then is quickly put into quenching oil at 50 ℃ for quenching for 20s, and then is quickly put into isothermal molten salt bath medium (KNO with the weight ratio of 1: 1) at 270 DEG C3With NaNO2Mixture) was incubated for 2h, followed by water cooling. Performance of the material after heat treatment: hardness 57HRC, impact energy 25J.
Compared with the traditional heat treatment process, the invention has the advantages that the impact toughness of the prepared alloy material is improved, and the hardness is not reduced but improved. Therefore, the alloy material processed by the process of the invention is used for manufacturing the hob of the shield machine, so that the hob has the advantages of high hardness and high impact toughness.
Detailed Description
The present invention is further illustrated by the following examples, which are not to be construed as limiting the invention.
Example 1. A heat treatment method of high-hardness high-impact-toughness alloy material comprises the steps of austenitizing the material, and then putting the austenitized material into quenching oil for quenching treatment; after quenching treatment, putting the material into an isothermal molten salt bath medium for heat preservation and distribution treatment; and (3) after the distribution treatment, putting the material into room temperature water or oil for cooling treatment to obtain the product.
Specifically, the austenitizing treatment is as follows: and (3) preserving the heat of the material for 30-60 min at the heat preservation temperature of 900-1000 ℃. Through the treatment, the alloy elements in the material are fully dissolved in the solution, and the crystal grains are not grown.
Specifically, the holding temperature in the austenitizing treatment was 950 ℃.
Specifically, the quenching treatment comprises the following steps: and keeping the temperature in quenching oil at the temperature of 50-150 ℃ for 15-40 s. This treatment can partially transform austenite in the material, and the structure after the quenching treatment can be metastable austenite of about + 10% of quenched martensite.
Specifically, the quenching treatment comprises the following steps: when the thickness of the section of the material is less than 50mm, keeping the temperature in quenching oil at the temperature of 50-150 ℃ for 15-30 s at constant temperature; when the section thickness of the material is more than 50mm, keeping the temperature for 30-40 s in quenching oil at the constant temperature of 50-150 ℃.
Specifically, the allocation process comprises the following steps: and preserving the heat for 1-3 h in an isothermal molten salt bath medium at 270-320 ℃. This treatment completes the transformation of part of the metastable austenite to bainite and the recovery of the quenched martensite. And finally, after the material is cooled to room temperature by quenching oil or water, the structure of the material is a mixed structure consisting of martensite, bainite, residual austenite and a small amount of carbide, and the structure enables the material to have the characteristics of high hardness and high toughness, so that the service life of the material prepared by rolling is effectively prolonged.
Is characterized in that the shield machine hob material has high hardness and high toughness
Specifically, the heat preservation time of the partitioning treatment was 2 hours.
Specifically, the salt bath medium is KNO3With NaNO2A mixture of (a).
Specifically, said KNO3With NaNO2The weight ratio of the mixture was 1: 1.

Claims (9)

1. A heat treatment method of high-hardness high-impact-toughness alloy material is characterized in that the material is placed into quenching oil for quenching treatment after austenitizing treatment; after quenching treatment, putting the material into an isothermal molten salt bath medium for heat preservation and distribution treatment; and (3) after the distribution treatment, putting the material into room temperature water or oil for cooling treatment to obtain the product.
2. The heat treatment method for the high-hardness high-impact-toughness alloy material according to claim 1, wherein the austenitizing treatment is: and (3) preserving the heat of the material for 30-60 min at the heat preservation temperature of 900-1000 ℃.
3. The method for heat-treating a high-hardness high-impact-toughness alloy material according to claim 2, wherein the holding temperature during the austenitizing treatment is 950 ℃.
4. The heat treatment method for high-hardness high-impact-toughness alloy material according to claim 1, wherein the quenching treatment is: and keeping the temperature in quenching oil at the temperature of 50-150 ℃ for 15-40 s.
5. The heat treatment method for the high-hardness high-impact-toughness alloy material according to claim 4, wherein the quenching treatment is: when the thickness of the section of the material is less than 50mm, keeping the temperature in quenching oil at the temperature of 50-150 ℃ for 15-30 s at constant temperature; when the section thickness of the material is more than 50mm, keeping the temperature for 30-40 s in quenching oil at the constant temperature of 50-150 ℃.
6. The heat treatment method for the high-hardness high-impact-toughness alloy material according to claim 1, wherein the distribution treatment comprises the following steps: and preserving the heat for 1-3 h in an isothermal molten salt bath medium at 270-320 ℃.
7. The heat treatment method for high-hardness high-impact-toughness alloy material according to claim 6, wherein the heat preservation time of the distribution treatment is 2 hours.
8. The heat treatment method of high-hardness high-impact-toughness alloy material according to claim 6, wherein the salt bath medium is KNO3With NaNO2A mixture of (a).
9. The method as claimed in claim 8, wherein said KNO is selected from the group consisting of3With NaNO2The weight ratio of the mixture was 1: 1.
CN201911342800.0A 2019-12-23 2019-12-23 Heat treatment method of high-hardness high-impact-toughness alloy material Pending CN110964890A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111621825A (en) * 2020-04-17 2020-09-04 安徽澳新工具有限公司 Surface treatment method for hard alloy steel hammer with strong wear resistance
CN112267009A (en) * 2020-10-23 2021-01-26 江苏大学 Water-soluble quenching liquid, preparation method thereof, method for treating shield tunneling machine cutter ring and quenching shield tunneling machine cutter ring

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005336570A (en) * 2004-05-28 2005-12-08 Nachi Fujikoshi Corp Method for oil-quenching steel, and apparatus therefor
CN101225499A (en) * 2008-01-31 2008-07-23 上海交通大学 Low-alloy super-strength multiphase steel and heat treatment method thereof
CN103243275A (en) * 2013-04-03 2013-08-14 北京交通大学 Preparation method of bainite/martensite/austenite composite high-strength steel
CN110055380A (en) * 2019-05-21 2019-07-26 中国第一汽车股份有限公司 A kind of prestressing force isothermal hardening method improving few leaf spring performance

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005336570A (en) * 2004-05-28 2005-12-08 Nachi Fujikoshi Corp Method for oil-quenching steel, and apparatus therefor
CN101225499A (en) * 2008-01-31 2008-07-23 上海交通大学 Low-alloy super-strength multiphase steel and heat treatment method thereof
CN103243275A (en) * 2013-04-03 2013-08-14 北京交通大学 Preparation method of bainite/martensite/austenite composite high-strength steel
CN110055380A (en) * 2019-05-21 2019-07-26 中国第一汽车股份有限公司 A kind of prestressing force isothermal hardening method improving few leaf spring performance

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111621825A (en) * 2020-04-17 2020-09-04 安徽澳新工具有限公司 Surface treatment method for hard alloy steel hammer with strong wear resistance
CN112267009A (en) * 2020-10-23 2021-01-26 江苏大学 Water-soluble quenching liquid, preparation method thereof, method for treating shield tunneling machine cutter ring and quenching shield tunneling machine cutter ring

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Application publication date: 20200407