阅读说明：本技术 一种新型热处理用淬火介质 (Novel quenching medium for heat treatment ) 是由 闵学刚 祁卫东 张钦霞 贾砚林 王林烽 胡勇 田俊玲 陈阿平 于 2020-06-18 设计创作，主要内容包括：一种新型热处理用淬火介质,该淬火介质包含液相和固相,淬火介质中固相的体积分数为0.01％～90％,且固相在液相中处于被浸润状态；所述液相为液态或熔融态淬火液,固相为单质、化合物粉末或颗粒,且固相与液相导热系数之比≥1.5。本发明所述淬火介质结合了固相颗粒的高导热性和液相优异的流动性,可以灵活调节淬火介质的综合导热系数,大大扩展淬火介质的热传导能力范围,提高对不同尺寸工件的热处理加工能力和灵活性。(A novel quenching medium for heat treatment comprises a liquid phase and a solid phase, wherein the volume fraction of the solid phase in the quenching medium is 0.01-90%, and the solid phase is in an infiltrated state in the liquid phase; the liquid phase is liquid or molten quenching liquid, the solid phase is simple substance, compound powder or particles, and the ratio of the heat conductivity coefficient of the solid phase to the heat conductivity coefficient of the liquid phase is more than or equal to 1.5. The quenching medium combines the high thermal conductivity of solid-phase particles and the excellent liquidity of a liquid phase, can flexibly adjust the comprehensive thermal conductivity coefficient of the quenching medium, greatly expands the range of the thermal conductivity of the quenching medium, and improves the heat treatment processing capacity and flexibility of workpieces with different sizes.)

1. The novel quenching medium for heat treatment is characterized by comprising a liquid phase and a solid phase, wherein the volume fraction of the solid phase in the quenching medium is 0.01-90%, and the solid phase is in an infiltrated state in the liquid phase; the liquid phase is liquid or molten quenching liquid, the solid phase is simple substance, compound powder or particles, and the ratio of the heat conductivity coefficient of the solid phase to the heat conductivity coefficient of the liquid phase is more than or equal to 1.5.

2. The novel quenching medium for heat treatment as claimed in claim 1, wherein the quenching liquid is a water-based quenching liquid, an oil-based quenching liquid, a molten salt or a molten metal.

3. The novel quenching medium for heat treatment as claimed in claim 1, wherein said solid phase is Al powder or particles, Cu powder or particles, graphite powder or particles, diamond powder or particles, SiC powder or particles, Si₃N₄One or more of powder or particles, Ag powder or particles, Au powder or particles, Si powder or particles, Ca powder or particles, WC powder or particles, BeO powder or particles, AlN powder or particles, MWCNT powder or particles.

4. The novel quenching medium for heat treatment as claimed in claim 1, wherein the volume fraction of solid phase in the quenching medium is 5-70%.

5. The novel thermal processing quench medium as claimed in claim 1, characterized in that said solid phase is homogeneously distributed in the liquid phase.

6. The novel thermal processing quench medium of claim 1, wherein said solid phase is stratified with a liquid phase.

7. The method of using a novel quenching medium for heat treatment as claimed in claim 6, wherein the quenching medium is sufficiently stirred to uniformly distribute a solid phase in a liquid phase during use.

Technical Field

The invention belongs to the technical field of heat treatment of metal products, and particularly relates to a novel quenching medium for heat treatment.

Background

The quenching medium is usually a single-phase liquid, i.e. a quenching liquid, which is a cooling medium used in heat treatment quenching of metal materials widely used at home and abroad, and is used in various steel mills, steel wire mills, steel rope mills, steel part mills and the like, and the most commonly used steel wire quenching liquid comprises a water-based quenching liquid, an oil-based quenching liquid, molten salt, molten metal and the like.

Water is the most economical quenching medium, has high chemical stability and large heat capacity, and has good cooling capacity at about 300 ℃, but has not strong cooling capacity at a high temperature region, which is the reason why pure water is rarely used. Usually, some solvent is added into water to form water-based quenching liquid for quenching, such as saline water, alkaline water, saturated calcium chloride, trinitro aqueous solution, organic polymer aqueous solution, and the like.

The oil has a cooling capacity weaker than that of water, but still has a sufficient cooling capacity, and the quenching capacity is not greatly affected when the oil temperature is increased, so that the quenching medium is ideal. However, the oil is cooled at a slow rate, and thus has a limitation in use. In order to improve the cooling capacity of the oil, additives such as sodium sulfonate and the like can be added, and the additives can be adhered to the surface of the steel wire to form mass points of steam bubbles, so that a stable steam film is not easy to form, and the cooling capacity of a high-temperature area is improved, so that the rapid quenching oil is called as rapid quenching oil.

The molten heat bath refers to quenching and cooling performed in a molten material such as molten salt or molten metal. For example, molten salt quenching is to dip a steel wire in a molten salt solution of a salt such as molten sodium nitrate or potassium nitrate as a medium to quench the steel wire. The salt bath furnace has the advantages of high heat conduction speed and uniform temperature, the steel wire is always in the salt solution, and the surface of the steel wire is attached with a salt film when the steel wire is discharged from the furnace, so that the surface oxidation and decarburization of the steel wire can be prevented. Molten salts have a lower thermal conductivity than molten metals, but are used in many cases because they have a lower density than molten metals and can achieve the same cooling effect as lead and bismuth baths by transferring heat with stirring.

The thermal conductivity of different base quenching media is approximately as follows according to different components: the thermal conductivity of the water-based quenching liquid is about 0.5-0.8W/(m.K), the thermal conductivity of the oil-based quenching liquid is about 0.1-0.5W/(m.K), and the thermal conductivity of the molten salt is about 0.4-0.9W/(m.K). Different molten metals have different thermal conductivities, e.g., about 5.53W/(mK) for molten lead, about 13W/(mK) for molten bismuth, etc. The range of the heat conductivity coefficients of the quenching media is relatively narrow or fixed, for example, a high-carbon steel wire rod or an alloy steel wire rod with the diameter of 5-20 mm is processed into various steel wire products such as a bridge steel wire, a spring steel wire, a steel cord steel wire and a diamond wire steel wire through a drawing process. The finest technological level can be drawn to 0.04mm, and the highest reduction rate reaches 99.9936%. The heat treatment of the wire rod, the heat treatment of the intermediate product in the drawing process, the heat treatment process of which determines the internal structure of the steel wire. At present, the most suitable structure for drawing is pearlite and sorbite, and the steel wire can be normally produced without broken wire in the subsequent drawing of the steel wire and reach the required strength and plasticity indexes only when the structure is well regulated and controlled by a heat treatment process after the steel wire is quenched. The most important of the regulation of the heat treatment process is realized by regulating the quenching capacity of the quenching medium, so how to improve the adjustable range of the heat conduction of the quenching medium is a problem to be solved urgently at present.

For the quenching process with various product forms and different customer requirements, once each heat treatment quenching line is designed and installed, the specification and the quenching effect of the product are relatively fixed, the adjustable space is small, and the quenching process has great limitation. For example, one design capability isThe molten salt bath quenching line of (1) is difficult to be fully quenched due to the limited heat conduction speed of the quenching liquidAnd the steel wire above. Want to quench throughAnd the above steel wires, require quenching conditions that are more thermally conductive.

Chinese patent CN111004898A discloses an oily water-soluble quenching liquid and a preparation method thereof, the oily water-soluble quenching liquid has wider application range, can obtain different cooling speeds by adjusting concentration, has smaller deformation than other polymers, can be used for quenching and cooling high-hardenability materials or alloy materials with smaller size, replaces mineral oil for quenching, eliminates fire hazard, and has higher safety.

Chinese patent CN102978357A discloses a water-based quenching agent for ultra-high carbon steel, which is suitable for quenching ultra-high carbon steel, wherein the structure of the quenched ultra-high carbon steel is ultra-fine martensite, so that the ultra-high carbon steel has good wear resistance and fatigue resistance.

Chinese patent CN105274292A discloses a water-sand quenching medium for medium and low carbon steel and a quenching process thereof, wherein the water-sand quenching medium is used for quenching medium and low carbon steel, so that the occurrence of quenching soft spots can be effectively prevented, and the hardness is improved; the steam film formed by water vaporization at high temperature is effectively removed, the cooling speed is controlled in different temperature areas in the quenching process, and the workpiece is prevented from deforming or cracking. The water-sand quenching medium is easy to obtain and low in price; the quenching heat preservation time is shorter, and the method has the characteristics of energy conservation, economy and environmental protection.

In the prior art, single-phase quenching liquid is improved, or a heat treatment quenching method is improved. There is no method for regulating and controlling the comprehensive heat conductivity coefficient of the quenching medium by utilizing different heat conductivity coefficients of solid and liquid phases.

Disclosure of Invention

The invention aims to provide a novel quenching medium for heat treatment, the heat conductivity coefficient of the quenching medium can be regulated and controlled in a larger range, the heat conductivity range of the quenching medium is greatly expanded, and the heat treatment processing capacity and flexibility of products with different sizes are improved.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a novel quenching medium for heat treatment comprises a liquid phase and a solid phase, wherein the volume fraction of the solid phase in the quenching medium is 0.01-90%, and the solid phase can be in an infiltrated state in the liquid phase; the liquid phase is liquid or molten quenching liquid, the solid phase is simple substance, compound powder or particles, and the ratio of the heat conductivity coefficient of the solid phase to the heat conductivity coefficient of the liquid phase is more than or equal to 1.5.

Preferably, the quenching liquid is water-based quenching liquid, oil-based quenching liquid, molten salt or molten metal.

Preferably, the solid phase is Al powder or particles, Cu powder or particles, graphite powder or particles, diamond powder or particles, SiC powder or particles, Si₃N₄One or more of powder or particles, Ag powder or particles, Au powder or particles, Si powder or particles, Ca powder or particles, WC powder or particles, BeO powder or particles, AlN powder or particles, MWCNT powder or particles.

Preferably, the volume fraction of the solid phase in the quenching medium is 5-70%.

Preferably, the solid phase is homogeneously distributed in the liquid phase.

Preferably, the solid phase is separated from the liquid phase.

Preferably, the quench medium is agitated sufficiently to provide a uniform distribution of the solid phase in the liquid phase during use.

The invention adds metal or nonmetal powder or particles with good heat conductivity into liquid or molten quenching liquid to form a quenching medium consisting of a solid phase and a liquid phase. The quenching medium combines the high thermal conductivity of the solid phase and the excellent fluidity of the liquid phase, and the comprehensive thermal conductivity of the quenching medium is flexibly designed by adjusting the volume fraction of the solid phase, so that the heat conductivity range of the quenching medium is greatly expanded, the adjustability and controllability of the thermal conductivity are realized, the heat treatment processing capacity and flexibility of workpieces with different sizes are improved, and a better quenching effect is achieved.

The thermal conductivity of each medium is compared as follows:

the molten salt (sodium nitrate and potassium nitrate salt) had a steady state thermal conductivity of 0.52W/(mK), the water had a thermal conductivity of 0.7W/(mK), the molten lead had a thermal conductivity of 5.53W/(mK), the molten bismuth had a thermal conductivity of 13W/(mK), the solid lead had a thermal conductivity of 34.8W/(mK), the Al had a thermal conductivity of 237W/(mK), the Cu had a thermal conductivity of 401W/(mK), the SiC had a steady state thermal conductivity of 83.6W/(mK), and the diamond had a thermal conductivity of 2300W/(mK).

When the solid phase and the liquid phase are mixed and the volume fraction of the solid phase is small, the solid phase particles are distributed and dispersed in the liquid phase, and the particles are separated by the liquid phase; when the volume fraction of the solid phase is increased, solid phase particles start to contact with each other in the liquid phase, a certain heat conduction chain can be formed, and the heat conductivity of the mixture starts to rapidly increase; as the volume fraction of the solid phase continues to increase, the liquid phase cannot infiltrate the solid phase particles, the mixture becomes a solid-liquid-gas three-phase system, and the thermal conductivity coefficient of the solid-liquid-gas three-phase system is reduced. Therefore, the heat conductivity coefficient of the quenching medium can be adjusted by adjusting the volume fraction of the solid phase and the liquid phase so as to meet the quenching conditions and the structure requirements of actual requirements.

In the process of simulating the heat conductivity coefficient of the system by using the heat conduction model:

when the volume fraction of solid-phase particles is less than 20%, the Maxwell model is simple and can well fit the thermal conductivity coefficient of the mixture, and the mathematical expression is as follows:

when the solid phase volume fraction is more than or equal to 20%, the Agari model can better accord with estimation, and the mathematical expression is as follows:

lgλ＝0.85υ₂lgλ₂+υ₁lgλ₁

in the formula, lambda is the equivalent thermal conductivity coefficient of the two composite materials; upsilon is₁，υ₂Volume fractions of component 1 and component 2, respectively; lambda [ alpha ]₁，λ₂The thermal conductivity of component 1 and component 2, respectively.

Therefore, the heat conductivity coefficient of the solid-liquid two-phase mixture can be adjusted according to the requirement so as to achieve the quenching condition and the structure result which are actually required.

The invention has the beneficial effects that:

1. according to the invention, metal or nonmetal solid-phase substance powder or particles with better heat conductivity are added into different quenching liquids, and the volume fraction of the solid-phase particles in the quenching medium is adjusted, so that the heat conductivity coefficient of the quenching medium is regulated and controlled within a larger range, the heat conductivity range of the quenching medium is greatly expanded, the heat conductivity after mixing is 1-200 times different than that of the original quenching liquid, and the heat treatment processing capacity and flexibility of products with different sizes are improved.

2. The quenching medium is more economical and practical in actual production, is convenient to operate, can realize the heat treatment of workpieces with different sizes without modifying a quenching line on a large scale, and meets the requirements of different product organizations and processes.

Detailed Description

The present invention will be further described with reference to the following examples.

The quenching medium comprises a liquid phase and a solid phase, and the volume fraction of the solid phase in the quenching medium is 0.01-90%, preferably 5-70%;

the liquid phase is liquid or molten quenching liquid, the solid phase is simple substance and compound particles, and the ratio of the heat conductivity coefficient of the solid phase to the heat conductivity coefficient of the liquid phase is more than or equal to 1.5.

The specific quench media compositions and properties of the examples of the invention are shown in Table 1.

As shown in Table 1, the heat conductivity of the quenching medium prepared according to the cost of the invention is improved by 1-200 times compared with the original quenching liquid, which shows that the heat conductivity coefficient of the quenching medium can be regulated and controlled in a larger range by regulating the volume fraction of solid-phase particles, thereby greatly expanding the range of the heat conductivity of the quenching medium.