阅读说明：本技术 一种不锈钢复合钢制对焊管件热处理工艺 (Heat treatment process for stainless steel composite steel butt-welded pipe fitting ) 是由 苏兴生 张睿 于 2021-08-31 设计创作，主要内容包括：本发明提出了一种不锈钢复合钢制对焊管件热处理工艺,包括一级处理、预加热、两段淬火、二级处理、一段回火,其中,一级处理、二级处理为采用不同润滑油含量的热传导液涂覆待加工管件,本申请优化了热处理工艺步骤,针对性调整淬火、回火时机和参数,同时配合两级处理,为管件提供了优异的热均衡性,温度传递高效稳定,大大提高了热处理质量,管件力学性能显著提高,有效使用寿命延长了一倍以上。(The invention provides a heat treatment process for a stainless steel composite steel butt-welded pipe fitting, which comprises primary treatment, preheating, two-stage quenching, secondary treatment and one-stage tempering, wherein the primary treatment and the secondary treatment are to adopt heat conduction liquids with different lubricating oil contents to coat the pipe fitting to be processed.)

1. A heat treatment process for a butt-welded stainless steel composite pipe fitting is characterized by comprising the following steps of: the method comprises the steps of primary treatment, preheating, two-stage quenching, secondary treatment and one-stage tempering, wherein the primary treatment and the secondary treatment are to coat the pipe fitting to be processed with heat transfer liquid with different lubricating oil contents.

2. The heat treatment process for the butt-welded stainless steel composite pipe fitting according to claim 1, characterized in that: the heat transfer liquid comprises hydrophobic silica sol particles, silicon nitride particles and polyacrylic acid emulsion, and the mass ratio of the hydrophobic silica sol particles to the silicon nitride particles to the polyacrylic acid emulsion is 2-5:0.5-1: 15-30.

3. The heat treatment process for the butt-welded stainless steel composite pipe fitting according to claim 2, characterized in that: the hydrophobic silica sol particles are methyl triethoxysilane modified silica sol, the oil contact angle is 8.6 +/-1.3 degrees, the hydrophobic silica sol particles are dried and then crushed until D90 is 50 mu m, the particle size of silicon nitride particles is less than 1 mu m, and the solid content of polyacrylic emulsion is 38 percent.

4. The heat treatment process for the butt-welded stainless steel composite pipe fitting according to any one of claims 1 to 3, characterized in that: the lubricating oil adopts 3# nano-base lubricating oil, the lubricating oil proportion in the first-stage treatment heat conduction liquid is 3-8vt%, and the lubricating oil proportion in the second-stage treatment heat conduction liquid is 10-12 vt%.

5. The heat treatment process for the butt-welded stainless steel composite pipe fitting according to claim 4, characterized in that: the first-stage treatment specifically comprises the steps of taking lubricating oil and heat transfer fluid according to a proportion, adding the lubricating oil into the heat transfer fluid under the stirring condition at the temperature of 45-50 ℃, and uniformly stirring to obtain coating fluid for later use; cleaning the pipe fitting to be processed, drying at 70 ℃ in an inert atmosphere, and then uniformly spraying the uniformly stirred coating liquid on the wall surface of the pipe fitting, wherein the spraying amount is 0.6-1L/m²(ii) a The second-stage treatment comprises proportionally taking lubricating oil and heat transfer liquid, adding lubricating oil into the heat transfer liquid at 45-50 deg.C under stirring,uniformly stirring to obtain coating liquid for later use; cleaning the pipe fitting to be processed, drying at 70 ℃ in an inert atmosphere, and then uniformly spraying the uniformly stirred coating liquid on the wall surface of the pipe fitting, wherein the spraying amount is 1.2-2L/m²。

6. The heat treatment process for the butt-welded stainless steel composite pipe fitting according to claim 5, characterized in that: after the first-stage treatment and the second-stage treatment, the spraying is finished, and the temperature is kept for 20-60min at 45 ℃ under the inert atmosphere.

7. The heat treatment process for the butt-welded stainless steel composite pipe fitting according to claim 1, characterized in that: the preheating is carried out by heating to 450-.

8. The heat treatment process for the butt-welded stainless steel composite pipe fitting according to claim 1, characterized in that: the two-stage quenching specifically comprises the following steps of,

s1, on the basis of the preheating temperature, firstly heating to 600-650 ℃ at the speed of 50 ℃/h, preserving the heat for 0.5-2h, then continuously heating to 850-980 ℃ at the speed of 80-100 ℃/h, preserving the heat for 1-4h, and then cooling to 300 ℃ at the speed of 200 ℃/h;

s2, preserving heat for 0.5-1h at 300 ℃, then raising the temperature to a temperature value lower than the maximum temperature by 150 ℃ at the speed of 45-50 ℃/h, then continuing raising the temperature to the maximum temperature at the speed of 30 ℃/h, preserving heat for 2-4h, then lowering the temperature to 300 ℃ at the speed of 200 ℃/h, and then naturally cooling; wherein the maximum temperature is 730-.

9. The heat treatment process for the butt-welded stainless steel composite pipe fitting according to claim 1, characterized in that: the first-stage tempering is specifically that the temperature is raised to 380-cost 430 ℃ at the speed of 40 ℃/h, the temperature is preserved for 1-2h, then the temperature is continuously raised to 620-cost 660 ℃ at the speed of 50-55 ℃/h, the temperature is preserved for 2-3h, then the temperature is lowered to 300 ℃ at the speed of stepwise temperature reduction, and the temperature is naturally cooled to the room temperature.

10. The heat treatment process for the butt-welded stainless steel composite pipe fitting according to claim 9, characterized in that: the stepped cooling rate is 5 ℃/h as a variation difference, the cooling rate of 50 ℃/h is increased to 20 ℃/h, and finally the cooling rate of 20 ℃/h is kept constant.

Technical Field

The invention relates to the technical field of processing of stainless steel composite steel butt-welded pipe fittings, in particular to a heat treatment process for a stainless steel composite steel butt-welded pipe fitting.

Background

The steel is a building material widely applied in modern building industry, and particularly, in pipeline engineering, steel pipes with large and small sizes are applied to gas, water and oil transmission lines. The composite steel pipe is a steel pipe which takes a seamless steel pipe and a welded steel pipe as base pipes and is coated with polyethylene powder coating or epoxy resin coating with high adhesive force, corrosion resistance and food-grade sanitation.

The heat treatment process of the steel pipe is to heat the steel pipe workpiece to a certain temperature and keep the temperature for a period of time, and then to cool the steel pipe workpiece at a certain cooling speed. The steel pipe heat treatment is a heat treatment method in which a steel pipe is heated to a temperature at which phase change or partial phase change occurs according to a certain temperature rise curve, and cooled at a certain cooling rate after heat preservation. The purpose of the heat treatment is to improve the structure and various properties of the steel pipe to meet the use requirements of the steel pipe.

The traditional heat treatment process parameters comprise normalizing or quenching heating temperature, heat preservation time, tempering temperature, heat preservation time, cooling speed and the like. In the traditional process design, parameters are generally only related to steel grade and steel grade, but the uniformity of heating temperature during high-capacity heating is less considered, but along with high-capacity heat treatment, temperature difference is easy to generate, and different sections of the same steel pipe or between the steel pipes are affected, so that quality damage is caused.

Disclosure of Invention

In view of the above, the present invention aims to provide a heat treatment process for a stainless steel composite steel butt-welded pipe fitting, which optimizes the heat treatment process steps, adjusts the quenching and tempering time and parameters in a targeted manner, and simultaneously cooperates with two-stage treatment to provide excellent heat balance for the pipe fitting, the temperature transfer is efficient and stable, the heat treatment quality is greatly improved, the mechanical properties of the pipe fitting are significantly improved, and the effective service life is prolonged by more than one time.

In order to achieve the purpose, the invention provides the following technical scheme:

a heat treatment process for a stainless steel composite steel butt-welded pipe fitting comprises primary treatment, preheating, two-stage quenching, secondary treatment and one-stage tempering, wherein the primary treatment and the secondary treatment are to coat the pipe fitting to be processed with heat conduction liquid with different lubricating oil contents.

More preferably, the heat transfer fluid comprises hydrophobic silica sol particles, silicon nitride particles and polyacrylic acid emulsion, and the mass ratio of the hydrophobic silica sol particles to the silicon nitride particles to the polyacrylic acid emulsion is 2-5:0.5-1: 15-30.

Further preferably, the hydrophobic silica sol particles are methyl triethoxysilane modified silica sol, the oil contact angle is 8.6 +/-1.3 degrees, the hydrophobic silica sol particles are dried and then crushed until D90 is 50 micrometers, the particle size of silicon nitride particles is less than 1 micrometer, and the solid content of the polyacrylic acid emulsion is 38 percent.

In a further preferred embodiment of the present invention, the lubricating oil is 3# nano-base lubricating oil, and the lubricating oil content in the first-stage treated heat transfer fluid is 3 to 8vt% and the lubricating oil content in the second-stage treated heat transfer fluid is 10 to 12 vt%.

Further preferably, the first-stage treatment comprises the steps of taking the lubricating oil and the heat transfer fluid according to a proportion, adding the lubricating oil into the heat transfer fluid under the stirring condition at 45-50 ℃, and uniformly stirring to obtain a coating fluid for later use; cleaning the pipe fitting to be processed, drying at 70 ℃ in an inert atmosphere, and then uniformly spraying the uniformly stirred coating liquid on the wall surface of the pipe fitting, wherein the spraying amount is 0.6-1L/m²(ii) a The second-stage treatment comprises proportionally taking lubricating oil and heat transfer liquid, adding the lubricating oil into the heat transfer liquid at 45-50 deg.C under stirring, and stirring to obtain coating liquid; cleaning the pipe fitting to be processed, drying at 70 ℃ in an inert atmosphere, and then uniformly spraying the uniformly stirred coating liquid on the wall surface of the pipe fitting, wherein the spraying amount is 1.2-2L/m²。

As a further optimization of the invention, after the primary treatment and the secondary treatment are finished, the temperature is kept for 20-60min at 45 ℃ under the inert atmosphere.

Further preferably, the preheating is carried out at a temperature of 120 ℃/h of 100-.

As a further preferred aspect of the present invention, the two-stage quenching is specifically,

s1, on the basis of the preheating temperature, firstly heating to 600-650 ℃ at the speed of 50 ℃/h, preserving the heat for 0.5-2h, then continuously heating to 850-980 ℃ at the speed of 80-100 ℃/h, preserving the heat for 1-4h, and then cooling to 300 ℃ at the speed of 200 ℃/h;

s2, preserving heat for 0.5-1h at 300 ℃, then raising the temperature to a temperature value lower than the maximum temperature by 150 ℃ at the speed of 45-50 ℃/h, then continuing raising the temperature to the maximum temperature at the speed of 30 ℃/h, preserving heat for 2-4h, then lowering the temperature to 300 ℃ at the speed of 200 ℃/h, and then naturally cooling; wherein the maximum temperature is 730-.

As a further preferred aspect of the present invention, the first-stage tempering is to heat the mixture to 380-430 ℃ at a rate of 40 ℃/h, preserve the heat for 1-2h, then continue to heat the mixture to 620-660 ℃ at a rate of 50-55 ℃/h, preserve the heat for 2-3h, then cool the mixture to 300 ℃ at a staged cooling rate, and naturally cool the mixture to room temperature.

Further preferably, the stepwise cooling rate is a rate which varies by 5 ℃/h from a cooling rate of 50 ℃/h up to 20 ℃/h and is finally kept constant at a cooling rate of 20 ℃/h.

The invention has the beneficial effects that: the invention optimizes the heat treatment process steps, adjusts the quenching and tempering time and parameters in a targeted manner, simultaneously cooperates with two-stage treatment, provides excellent heat balance for the pipe fitting, has high and stable temperature transfer, greatly improves the heat treatment quality, obviously improves the mechanical property of the pipe fitting, and prolongs the effective service life by more than one time.

The heat conduction liquid takes polyacrylic acid emulsion as a main solvent, the adhesion is regulated and controlled by compounding silica sol, the compatibility effect is favorably improved, the heat conduction liquid is coated on the surface of a steel pipe, the film forming property is good, the surface layer can be subjected to heat absorption protection, meanwhile, the silica sol is subjected to silane hydrophobic modification, the heat conduction liquid has a certain isolation effect on water on the surface of metal, and meanwhile, the heat conduction liquid has good promotion significance on oil load wrapping, and the carrying of a proper amount of lubricating oil can effectively balance the heating degree in the high-temperature process, is heated compared with water vapor, has milder and more stable heat treatment effect, and obviously improves the homogenization effect of the pipe. In addition, silicon nitride particles are also cooperated and uniformly dispersed in the heat conduction liquid, so that high-temperature impact is relieved, and meanwhile, the silicon nitride particles are reinforced, and after heat treatment, the silicon nitride particles are used as high-temperature-resistant solid cores, so that an aggregation center can be formed, the carbonized or caked outer membrane can be rapidly separated, and the silicon nitride particles are simple and convenient.

The pipeline manufactured by the high-temperature heat treatment method has the advantages of excellent mechanical property improvement, high uniformity and high strength, synchronously improved product percent of pass, good comprehensive benefit and worth of application and popularization.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.

Example 1:

a heat treatment process for a stainless steel composite steel butt-welded pipe fitting comprises primary treatment, preheating, two-stage quenching, secondary treatment and one-stage tempering, wherein the primary treatment and the secondary treatment are to coat the pipe fitting to be processed with heat conduction liquid with different lubricating oil contents.

The heat conduction liquid comprises hydrophobic silica sol particles, silicon nitride particles and polyacrylic emulsion, and the mass ratio of the hydrophobic silica sol particles to the silicon nitride particles to the polyacrylic emulsion is 5: 1:28. And the hydrophobic silica sol particles are methyl triethoxysilane modified silica sol, the oil contact angle is 8.6 +/-1.3 degrees, the hydrophobic silica sol particles are dried and then crushed until D90 is 50 mu m, the particle size of silicon nitride particles is less than 1 mu m, and the solid content of the polyacrylic acid emulsion is 38 percent.

Furthermore, the lubricating oil is 3# nano-base lubricating oil, the lubricating oil proportion in the first-stage treatment heat conduction liquid is 6.2 vt%, and the lubricating oil proportion in the second-stage treatment heat conduction liquid is 10.5 vt%.

Specifically, the process treatment method comprises the following steps:

the first-stage treatment specifically comprises the steps of taking lubricating oil and heat transfer fluid according to a proportion, adding the lubricating oil into the heat transfer fluid under the condition of stirring at 50 ℃, and uniformly stirring to obtain a coating fluid for later use; cleaning the pipe fitting to be processed, drying at 70 ℃ in an inert atmosphere, and then uniformly spraying the uniformly stirred coating liquid on the wall surface of the pipe fitting, wherein the spraying amount is 0.78L/m²(ii) a The second-stage treatment comprises the steps of taking lubricating oil and heat transfer fluid according to a proportion, adding the lubricating oil into the heat transfer fluid under the condition of stirring at 50 ℃, and uniformly stirring to obtain coating fluid for later use; cleaning the pipe fitting to be processed, drying at 70 ℃ in an inert atmosphere, and then uniformly spraying the uniformly stirred coating liquid on the wall surface of the pipe fitting, wherein the spraying amount is 1.66L/m²。

Wherein, after the first-stage treatment and the second-stage treatment, the spraying is finished, and the temperature is kept for 40min at 45 ℃ under the inert atmosphere.

The preheating is carried out specifically by raising the temperature to 440 ℃ at a speed of 110 ℃/h and keeping the temperature for 2 h.

The two-stage quenching is specifically that,

s1, on the basis of the preheating temperature, heating to 620 ℃ at the speed of 50 ℃/h, preserving heat for 1.5h, then continuing heating to 920 ℃ at the speed of 100 ℃/h, preserving heat for 3h, and then cooling to 300 ℃ at the speed of 200 ℃/h;

s2, preserving heat at 300 ℃ for 1h, then heating to a temperature value lower than the maximum temperature by 150 ℃ at a speed of 50 ℃/h, then continuously heating to the maximum temperature at a speed of 30 ℃/h, preserving heat for 4h, then cooling to 300 ℃ at a speed of 200 ℃/h, and then naturally cooling; with a maximum temperature of 850 ℃.

The first-stage tempering is specifically that the temperature is increased to 400 ℃ at the speed of 40 ℃/h, the temperature is kept for 2h, then the temperature is continuously increased to 650 ℃ at the speed of 50 ℃/h, the temperature is kept for 2h, then the temperature is reduced to 300 ℃ at the speed of stepwise temperature reduction, and the temperature is naturally cooled to the room temperature. Wherein the step-type cooling rate is 5 ℃/h as a variation difference, the cooling rate is from 50 ℃/h to 20 ℃/h, and finally the cooling rate is kept constant at 20 ℃/h.

Example 2:

a heat treatment process for a stainless steel composite steel butt-welded pipe fitting comprises primary treatment, preheating, two-stage quenching, secondary treatment and one-stage tempering, wherein the primary treatment and the secondary treatment are to coat the pipe fitting to be processed with heat conduction liquid with different lubricating oil contents.

The heat conduction liquid comprises hydrophobic silica sol particles, silicon nitride particles and polyacrylic emulsion, and the mass ratio of the hydrophobic silica sol particles to the silicon nitride particles to the polyacrylic emulsion is 3:0.5: 15. And the hydrophobic silica sol particles are methyl triethoxysilane modified silica sol, the oil contact angle is 8.6 +/-1.3 degrees, the hydrophobic silica sol particles are dried and then crushed until D90 is 50 mu m, the particle size of silicon nitride particles is less than 1 mu m, and the solid content of the polyacrylic acid emulsion is 38 percent.

Furthermore, 3# nano-base lubricating oil is adopted as the lubricating oil, the lubricating oil proportion in the first-stage treatment heat transfer fluid is 8.0 vt%, and the lubricating oil proportion in the second-stage treatment heat transfer fluid is 11.5 vt%.

Specifically, the process treatment method comprises the following steps:

the first-stage treatment specifically comprises the steps of taking lubricating oil and heat transfer fluid according to a proportion, adding the lubricating oil into the heat transfer fluid under the condition of stirring at 50 ℃, and uniformly stirring to obtain a coating fluid for later use; cleaning a pipe fitting to be processed and then putting the pipe fitting in an inert atmosphereDrying at 70 deg.C, and uniformly spraying the coating solution on the wall surface of the pipe fitting with a spraying amount of 0.8L/m²(ii) a The second-stage treatment comprises the steps of taking lubricating oil and heat transfer fluid according to a proportion, adding the lubricating oil into the heat transfer fluid under the condition of stirring at 50 ℃, and uniformly stirring to obtain coating fluid for later use; cleaning the pipe fitting to be processed, drying at 70 ℃ in an inert atmosphere, and then uniformly spraying the uniformly stirred coating liquid on the wall surface of the pipe fitting, wherein the spraying amount is 1.7L/m²。

Wherein, after the first-stage treatment and the second-stage treatment, the spraying is finished, and the temperature is kept for 40min at 45 ℃ under the inert atmosphere.

The preheating is carried out specifically by heating to 450 ℃ at a speed of 100 ℃/h and keeping the temperature for 2.5 h.

The two-stage quenching is specifically that,

s1, on the basis of the preheating temperature, heating to 600 ℃ at the speed of 50 ℃/h, keeping the temperature for 1h, then continuing heating to 950 ℃ at the speed of 90 ℃/h, keeping the temperature for 1.5h, and then cooling to 300 ℃ at the speed of 200 ℃/h;

s2, preserving heat for 0.8h at 300 ℃, then heating to a temperature value lower than the maximum temperature by 150 ℃ at a speed of 45 ℃/h, then continuously heating to the maximum temperature at a speed of 30 ℃/h, preserving heat for 3h, then cooling to 300 ℃ at a speed of 250 ℃/h, and then naturally cooling; with a maximum temperature of 800 ℃.

The first-stage tempering is specifically that the temperature is increased to 430 ℃ at the speed of 40 ℃/h, the temperature is kept for 1h, then the temperature is continuously increased to 660 ℃ at the speed of 55 ℃/h, the temperature is kept for 2h, then the temperature is reduced to 300 ℃ at the speed of stepwise temperature reduction, and the temperature is naturally cooled to the room temperature. Wherein the step-type cooling rate is 5 ℃/h as a variation difference, the cooling rate is from 50 ℃/h to 20 ℃/h, and finally the cooling rate is kept constant at 20 ℃/h.

Example 3:

a heat treatment process for a stainless steel composite steel butt-welded pipe fitting comprises primary treatment, preheating, two-stage quenching, secondary treatment and one-stage tempering, wherein the primary treatment and the secondary treatment are to coat the pipe fitting to be processed with heat conduction liquid with different lubricating oil contents.

The heat conduction liquid comprises hydrophobic silica sol particles, silicon nitride particles and polyacrylic acid emulsion, and the mass ratio of the hydrophobic silica sol particles to the silicon nitride particles to the polyacrylic acid emulsion is 2:0.6: 20. And the hydrophobic silica sol particles are methyl triethoxysilane modified silica sol, the oil contact angle is 8.6 +/-1.3 degrees, the hydrophobic silica sol particles are dried and then crushed until D90 is 50 mu m, the particle size of silicon nitride particles is less than 1 mu m, and the solid content of the polyacrylic acid emulsion is 38 percent.

Furthermore, 3# nano-base lubricating oil is adopted as the lubricating oil, the lubricating oil proportion in the first-stage treatment heat conduction liquid is 4.5 vt%, and the lubricating oil proportion in the second-stage treatment heat conduction liquid is 10.6 vt%.

Specifically, the process treatment method comprises the following steps:

the first-stage treatment specifically comprises the steps of taking lubricating oil and heat transfer fluid according to a proportion, adding the lubricating oil into the heat transfer fluid under the condition of stirring at 45 ℃, and uniformly stirring to obtain a coating fluid for later use; cleaning a pipe fitting to be processed, drying the pipe fitting at 70 ℃ in an inert atmosphere, and then uniformly spraying the uniformly stirred coating liquid on the wall surface of the pipe fitting, wherein the spraying amount is 1L/m²(ii) a The second-stage treatment comprises the steps of taking lubricating oil and heat transfer fluid according to a proportion, adding the lubricating oil into the heat transfer fluid under the condition of stirring at 45 ℃, and uniformly stirring to obtain coating fluid for later use; cleaning the pipe fitting to be processed, drying at 70 ℃ in an inert atmosphere, and then uniformly spraying the uniformly stirred coating liquid on the wall surface of the pipe fitting, wherein the spraying amount is 1.9L/m²。

Wherein, after the first-stage treatment and the second-stage treatment, the spraying is finished, and the temperature is kept for 60min at 45 ℃ under the inert atmosphere.

Preheating is carried out by heating to 450 ℃ at a speed of 120 ℃/h and keeping the temperature for 2.5 h.

The two-stage quenching is specifically that,

s1, on the basis of the preheating temperature, heating to 620 ℃ at the speed of 50 ℃/h, keeping the temperature for 0.5h, then continuing heating to 960 ℃ at the speed of 80 ℃/h, keeping the temperature for 2h, and then cooling to 300 ℃ at the speed of 200 ℃/h;

s2, preserving heat at 300 ℃ for 1h, then heating to a temperature value lower than the maximum temperature by 150 ℃ at a speed of 50 ℃/h, then continuously heating to the maximum temperature at a speed of 30 ℃/h, preserving heat for 2h, then cooling to 300 ℃ at a speed of 200 ℃/h, and then naturally cooling; with a maximum temperature of 850 ℃.

The first-stage tempering is specifically that the temperature is raised to 380 ℃ at the speed of 40 ℃/h, the temperature is kept for 2h, then the temperature is raised to 620 ℃ at the speed of 555 ℃/h, the temperature is kept for 3h, then the temperature is lowered to 300 ℃ at the speed of stepwise temperature reduction, and the temperature is naturally cooled to the room temperature. Wherein the step-type cooling rate is 5 ℃/h as a variation difference, the cooling rate is from 50 ℃/h to 20 ℃/h, and finally the cooling rate is kept constant at 20 ℃/h.

Example 4:

a heat treatment process for a stainless steel composite steel butt-welded pipe fitting comprises primary treatment, preheating, two-stage quenching, secondary treatment and one-stage tempering, wherein the primary treatment and the secondary treatment are to coat the pipe fitting to be processed with heat conduction liquid with different lubricating oil contents.

The heat conduction liquid comprises hydrophobic silica sol particles, silicon nitride particles and polyacrylic acid emulsion, and the mass ratio of the hydrophobic silica sol particles to the silicon nitride particles to the polyacrylic acid emulsion is 2.5:0.8: 25. And the hydrophobic silica sol particles are methyl triethoxysilane modified silica sol, the oil contact angle is 8.6 +/-1.3 degrees, the hydrophobic silica sol particles are dried and then crushed until D90 is 50 mu m, the particle size of silicon nitride particles is less than 1 mu m, and the solid content of the polyacrylic acid emulsion is 38 percent.

Furthermore, the lubricating oil is 3# nano-base lubricating oil, the lubricating oil proportion in the first-stage treatment heat conduction liquid is 5.0 vt%, and the lubricating oil proportion in the second-stage treatment heat conduction liquid is 10.5 vt%.

Specifically, the process treatment method comprises the following steps:

the first-stage treatment specifically comprises the steps of taking lubricating oil and heat transfer fluid according to a proportion, adding the lubricating oil into the heat transfer fluid under the condition of stirring at 45 ℃, and uniformly stirring to obtain a coating fluid for later use; cleaning the pipe fitting to be processed, drying at 70 ℃ in an inert atmosphere, and then uniformly spraying the uniformly stirred coating liquid on the wall surface of the pipe fitting, wherein the spraying amount is 1.25L/m²(ii) a The second-stage treatment comprises the steps of taking lubricating oil and heat transfer fluid according to a proportion, adding the lubricating oil into the heat transfer fluid under the condition of stirring at 45 ℃, and uniformly stirring to obtain coating fluid for later use; cleaning the pipe fitting to be processed, drying at 70 ℃ in an inert atmosphere, and then uniformly spraying the uniformly stirred coating liquid on the wall surface of the pipe fitting, wherein the spraying amount is 1.65L/m²。

Wherein, after the first-stage treatment and the second-stage treatment, the spraying is finished, and the temperature is kept for 60min at 45 ℃ under the inert atmosphere.

Preheating is carried out by heating to 450 ℃ at a speed of 120 ℃/h and keeping the temperature for 2.5 h.

The two-stage quenching is specifically that,

s1, on the basis of the preheating temperature, heating to 620 ℃ at the speed of 50 ℃/h, keeping the temperature for 0.5h, then continuing heating to 960 ℃ at the speed of 80 ℃/h, keeping the temperature for 2h, and then cooling to 300 ℃ at the speed of 200 ℃/h;

s2, preserving heat at 300 ℃ for 1h, then heating to a temperature value lower than the maximum temperature by 150 ℃ at a speed of 50 ℃/h, then continuously heating to the maximum temperature at a speed of 30 ℃/h, preserving heat for 2h, then cooling to 300 ℃ at a speed of 200 ℃/h, and then naturally cooling; with a maximum temperature of 850 ℃.

The first-stage tempering is specifically that the temperature is raised to 380 ℃ at the speed of 40 ℃/h, the temperature is kept for 2h, then the temperature is raised to 620 ℃ at the speed of 555 ℃/h, the temperature is kept for 3h, then the temperature is lowered to 300 ℃ at the speed of stepwise temperature reduction, and the temperature is naturally cooled to the room temperature. Wherein the step-type cooling rate is 5 ℃/h as a variation difference, the cooling rate is from 50 ℃/h to 20 ℃/h, and finally the cooling rate is kept constant at 20 ℃/h.

Example 5:

a heat treatment process for a stainless steel composite steel butt-welded pipe fitting comprises primary treatment, preheating, two-stage quenching, secondary treatment and one-stage tempering, wherein the primary treatment and the secondary treatment are to coat the pipe fitting to be processed with heat conduction liquid with different lubricating oil contents.

The heat conduction liquid comprises hydrophobic silica sol particles, silicon nitride particles and polyacrylic emulsion, and the mass ratio of the hydrophobic silica sol particles to the silicon nitride particles to the polyacrylic emulsion is 3:1: 30. And the hydrophobic silica sol particles are methyl triethoxysilane modified silica sol, the oil contact angle is 8.6 +/-1.3 degrees, the hydrophobic silica sol particles are dried and then crushed until D90 is 50 mu m, the particle size of silicon nitride particles is less than 1 mu m, and the solid content of the polyacrylic acid emulsion is 38 percent.

Furthermore, the lubricating oil is 3# nano-base lubricating oil, the lubricating oil proportion in the first-stage treatment heat conduction liquid is 8.3 vt%, and the lubricating oil proportion in the second-stage treatment heat conduction liquid is 11.2 vt%.

Specifically, the process treatment method comprises the following steps:

the first-stage treatment specifically comprises the steps of taking lubricating oil and heat transfer fluid according to a proportion, adding the lubricating oil into the heat transfer fluid under the condition of stirring at 50 ℃, and uniformly stirring to obtain a coating fluid for later use; cleaning the pipe fitting to be processed, drying at 70 ℃ in an inert atmosphere, and then uniformly spraying the uniformly stirred coating liquid on the wall surface of the pipe fitting, wherein the spraying amount is 0.85L/m²(ii) a The second-stage treatment comprises the steps of taking lubricating oil and heat transfer fluid according to a proportion, adding the lubricating oil into the heat transfer fluid under the condition of stirring at 50 ℃, and uniformly stirring to obtain coating fluid for later use; cleaning the pipe fitting to be processed, drying at 70 ℃ in an inert atmosphere, and then uniformly spraying the uniformly stirred coating liquid on the wall surface of the pipe fitting, wherein the spraying amount is 1.67L/m²。

Wherein, after the first-stage treatment and the second-stage treatment, the spraying is finished, and the temperature is kept for 40min at 45 ℃ under the inert atmosphere.

The preheating is carried out specifically by heating to 450 ℃ at a speed of 100 ℃/h and keeping the temperature for 2.5 h.

The two-stage quenching is specifically that,

s1, on the basis of the preheating temperature, heating to 600 ℃ at the speed of 50 ℃/h, keeping the temperature for 1h, then continuing heating to 950 ℃ at the speed of 90 ℃/h, keeping the temperature for 1.5h, and then cooling to 300 ℃ at the speed of 200 ℃/h;

s2, preserving heat for 0.8h at 300 ℃, then heating to a temperature value lower than the maximum temperature by 150 ℃ at a speed of 45 ℃/h, then continuously heating to the maximum temperature at a speed of 30 ℃/h, preserving heat for 3h, then cooling to 300 ℃ at a speed of 250 ℃/h, and then naturally cooling; with a maximum temperature of 800 ℃.

The first-stage tempering is specifically that the temperature is increased to 430 ℃ at the speed of 40 ℃/h, the temperature is kept for 1h, then the temperature is continuously increased to 660 ℃ at the speed of 55 ℃/h, the temperature is kept for 2h, then the temperature is reduced to 300 ℃ at the speed of stepwise temperature reduction, and the temperature is naturally cooled to the room temperature. Wherein the step-type cooling rate is 5 ℃/h as a variation difference, the cooling rate is from 50 ℃/h to 20 ℃/h, and finally the cooling rate is kept constant at 20 ℃/h.

Comparative examples 1 to 3:

based on the embodiment 1, the first-stage treatment step is removed, other conditions are unchanged, and the heat treatment process is also carried out;

based on the embodiment 1, the secondary treatment step is removed, other conditions are unchanged, and the heat treatment process is also carried out;

based on the embodiment 1, the steps of primary treatment and secondary treatment are removed, other conditions are unchanged, and the heat treatment process is also carried out;

the heat-treated pipes prepared in the examples and comparative examples of the present invention were subjected to performance tests, and the data are as follows:

it is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.