CN109778109B - Method for solving problem of unqualified carbonitriding quality - Google Patents
Method for solving problem of unqualified carbonitriding quality Download PDFInfo
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Abstract
The invention discloses a method for solving the problem of unqualified carbonitriding quality, which comprises the following steps: the method comprises the following steps of cleaning, carbonitriding heat treatment, tempering, quenching and secondary tempering, and is characterized in that a pretreatment process is carried out before carbonitriding, and the pretreatment process comprises the following specific steps: and (3) pretreating the cleaned workpiece to be treated for 0.5-1.5 h at the temperature of 900-930 ℃, and adopting nitrogen protection in the whole process when the pretreatment process is carried out. The method has the advantage of effectively solving the problems of soft spots and uneven seepage layer of the workpiece to be processed.
Description
Technical Field
The invention relates to the technical field of heat treatment, in particular to a method for solving the problem of unqualified carbonitriding quality.
Background
Carburizing is a chemical heat treatment process for increasing the carbon content and a certain carbon concentration gradient of the surface layer of a steel part, heating and preserving heat of the steel part in a carburizing medium to enable carbon atoms to permeate into the surface layer, and quenching and tempering after carburizing can improve the surface hardness, wear resistance and core toughness of the part. Carbonitriding is a heat treatment process which mainly performs nitriding and permeates carbon and nitrogen into the surface layer of a workpiece, and has the advantages of low hardness and small brittleness of a carburized layer, small deformation of the workpiece and no limitation of steel types, but the carburized layer of carbonitriding is thin and is not suitable for bearing heavy load.
The general process flow for solving the problem of unqualified carbonitriding quality of the bearing ring made of the alloy steel material comprises the following steps: cleaning, carbonitriding, low-temperature tempering, quenching, low-temperature tempering and the like, but when the product is subjected to carbonitriding in a furnace, soft spots appear on the surface, and the surface has lower carbon concentration and nitrogen concentration, which is concretely represented as that partial products are qualified and partial products are unqualified; the quality problems that part of the surface of the same product is qualified and part of the surface is unqualified are solved.
To solve the above problems, a series of pretreatment tests are performed before carbonitriding, for example, pretreatment processes including: pre-oxidizing for 1-2 h at 430-480 ℃; pre-oxidizing for 0.5-1.5 h at 500-550 ℃; acid washing; sand blasting, etc., however, the above problems cannot be solved yet.
The above prior art solutions have the following drawbacks: soft spots appear on the surface and the carburized layer is not uniform during carbonitriding.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method for solving the problem of unqualified carbonitriding quality, which has the advantage of effectively solving the problems of soft spots and uneven carburized layer of a workpiece to be treated.
In order to achieve the purpose, the invention provides the following technical scheme: a method for solving the problem of unqualified carbonitriding quality comprises the following steps: cleaning, carbonitriding heat treatment, tempering, quenching and secondary tempering, wherein a pretreatment process is carried out before carbonitriding, and the pretreatment process comprises the following specific steps: pretreating for 0.5-1.5 h at 900-930 ℃, and adopting nitrogen protection in the whole process when performing a pretreatment process.
By adopting the technical scheme, because the pretreatment process is adopted before the carbonitriding heat treatment, the austenitizing temperature is used for activating the surface of the product under the protection atmosphere of nitrogen to reach the austenite state, and the product is subjected to carbonitriding after being kept warm for a period of time and entering the carbonitriding atmosphere, so that the problem of non-uniformity of soft spots and a carburized layer of a workpiece can be effectively solved. When the workpiece is preheated, the workpiece is heated under the protection atmosphere of nitrogen, an oxide layer cannot be formed on the surface of the workpiece, the internal oxidation depth of the workpiece cannot be aggravated, and the quality of the workpiece can be improved to a certain extent.
In the name of the invention, when the bearing ring is subjected to carbonitriding heat treatment, a workpiece (bearing) to be processed is subjected to carbonitriding in a box-type multipurpose furnace, and at the moment, the atmosphere in the furnace is replaced by nitrogen before the workpiece enters the furnace; the workpiece enters the front chamber, and the air in the front chamber is fully replaced by high-pressure nitrogen, so that the air is prevented from entering the rear chamber when the workpiece enters the rear chamber; and (3) after the workpiece enters a rear chamber, preserving the heat for a certain time at the temperature of 900-930 ℃, always using nitrogen for protection, finally reducing the temperature to 840-860 ℃, and then entering a carbonitriding heat treatment step.
Further, the pretreatment process comprises the following specific steps: firstly, the cleaned workpiece to be processed is pretreated for 0.5-1.5 h at the temperature of 910-920 ℃.
By adopting the technical scheme, when the workpiece is pretreated, the pretreatment temperature is strictly controlled, the probability of soft spots on the surface of the workpiece can be reduced, the carbon concentration and the nitrogen concentration on the surface of the workpiece are improved, and the probability of uneven quality of the workpiece in the same furnace is reduced. In production, the temperature of pretreatment of different materials is different, the temperature can be finely adjusted according to the characteristics of the materials, and the heat preservation time can be correspondingly adjusted according to the size and the wall thickness of a workpiece.
Further, continuously keeping the product at 900-930 ℃ for 0.5-1.5 h, and reducing the temperature to 840-860 ℃.
By adopting the technical scheme, after the pretreatment process, the product is kept at 900-930 ℃ for 0.5-1.5 h, the temperature is reduced to 840-860 ℃, carbonitriding heat treatment is carried out, certain heat preservation and consolidation are carried out on the pretreated workpiece, and the quality difference between the workpieces in the same furnace can be reduced to a certain extent.
Further, the medium in the carbonitriding heat treatment includes nitrogen, methanol, natural gas, and ammonia gas.
By adopting the technical scheme, the medium for carbonitriding heat treatment comprises nitrogen, methanol, natural gas and ammonia gas, so that the carbon concentration and the nitrogen concentration on the surface of the workpiece can be improved, and the quality of the workpiece is improved to a certain extent. In the carbonitriding heat treatment, other atmosphere may be selected instead, for example, RX gas + natural gas + ammonia gas, as long as it is a gaseous carbonitriding atmosphere.
Further, the flow rate of the nitrogen is 2.5 +/-0.3 m3The flow rate of the methanol is 3 +/-0.3L/h, and the flow rate of the ammonia gas is 0.2-0.4 m3/h。
By adopting the technical scheme, during carbonitriding, the flow of each component in the medium is controlled, and the content of carbon and nitrogen in the medium can be controlled, so that the carbon concentration and the nitrogen concentration on the surface of the workpiece can be improved to a certain extent, and the quality of the workpiece is improved. The natural gas can be automatically adjusted according to the carbon potential, the flow rate does not need to be specially regulated, and the flow rate can be determined according to the size of equipment.
Further, the carbonitriding heat treatment is carried out at a temperature of 840 to 860 ℃.
By adopting the technical scheme, the carbonitriding heat treatment is carried out at 840-860 ℃, the size and shape change of the workpiece is extremely small, and the quality of the workpiece is convenient to improve.
Further, the method comprises the steps of:
(1) cleaning the workpiece to be treated by using a cleaning agent;
(2) a pretreatment process, namely using nitrogen as protective atmosphere to pretreat the cleaned workpiece to be treated for 0.5 to 1.5 hours at the temperature of 900 to 930 ℃; reducing the temperature to 840-860 ℃ within 0.5-1.5 h;
(3) and carbonitriding heat treatment: treating the pretreated workpiece by taking a mixture of nitrogen, methanol, natural gas and ammonia gas as a medium at 840-860 ℃, wherein the flow rate of the nitrogen is 2.5 +/-0.3 m3The flow rate of the methanol is 3 +/-0.3L/h, and the flow rate of the ammonia gas is 0.2-0.4 m3/h；
(4) And tempering: fully tempering the workpiece subjected to carbonitriding treatment at 180-200 ℃ for 3.8-5 h;
(5) and quenching: treating the tempered workpiece at 800-840 ℃ for 0.8-1.5 h;
(6) and secondary tempering: and (3) carrying out secondary tempering on the quenched workpiece at 180-200 ℃, wherein the secondary tempering time is 3.5-5 h.
Further, the method comprises the steps of:
(1) cleaning the workpiece to be treated by using a cleaning agent;
(2) a pretreatment process, namely pretreating the cleaned workpiece to be treated for 1h at 915 ℃ by using nitrogen as protective atmosphere; reducing the temperature to 850 ℃;
(3) and carbonitriding heat treatment: treating the pretreated workpiece by using a mixture of nitrogen, methanol, natural gas and ammonia gas as a medium at 850 ℃, wherein the flow of the nitrogen is 2.5m3The flow rate of methanol is 3L/h, and the flow rate of ammonia is 0.3m3/h；
(4) And tempering: fully tempering the workpiece subjected to carbonitriding at 200 ℃ for 4 hours;
(5) and quenching: treating the tempered workpiece at 820 ℃ for 1h;
(6) and secondary tempering: and (3) carrying out secondary tempering on the quenched workpiece at 190 ℃, wherein the secondary tempering time is 4 h.
In the invention, the cleaning agent sold in the market can be selected, and only impurities and oil stains on the surface of the workpiece can be removed. During pretreatment, a workpiece is heated at a high temperature of 900-930 ℃ and grains may grow, but subsequent quenching treatment can refine the grains, so that the quality of a final product is not affected. The traditional pickling treatment can increase working procedures, cause environmental pollution, cause the corrosion of workpieces easily, and cause unqualified quality of the workpieces due to nonuniform pickling. If sand blasting is used in the pretreatment, the sand blasting pollutes the environment, the sand blasting is not uniform, the product is unqualified, and the sand blasting efficiency is low. The preheating treatment process of the invention does not need acid washing and sand blasting, does not pollute the environment and does not influence the quality of the workpiece. Generally, the pre-oxidation treatment can solve the problems of uneven carburized layer and soft spots of many materials after carburization, carbonitriding and nitriding treatment. However, for some special steel grades, the conditions of uneven diffusion layer and soft spots cannot be solved by adopting pre-oxidation. The pretreatment process can solve the problems of nonuniform carburized layers and soft spots of a plurality of materials after carburization, carbonitriding and nitriding treatment, can also solve the problems of nonuniform carburized layers and soft spots of certain special steel grades, is obviously different from the traditional pre-oxidation and pretreatment methods, and has certain progress.
By adopting the technical scheme, the pretreatment process is adopted before the carbonitriding heat treatment, the austenitizing temperature is used under the nitrogen protection atmosphere to activate the surface of the product to reach the austenite state, and the product is subjected to carbonitriding after being kept warm for a period of time and entering the carbonitriding atmosphere, so that the problem of non-uniformity of soft spots and a carburized layer of a workpiece can be effectively solved.
In conclusion, the invention has the following beneficial effects:
firstly, because the pretreatment process is adopted before the carbonitriding heat treatment, the problems of soft spots and uneven diffusion layers of workpieces can be effectively solved;
secondly, when the workpiece is preheated, the workpiece is heated under the protective atmosphere of nitrogen, so that an oxide layer cannot be formed on the surface of the workpiece, and the internal oxidation depth of the workpiece cannot be aggravated;
thirdly, compared with acid washing and sand blasting, the pretreatment process in the carbonitriding heat treatment process does not pollute the environment, and can improve the treatment efficiency and the workpiece quality to a certain extent;
fourthly, the invention solves the problem that the preoxidation can not solve;
fifthly, the pretreatment process of the invention has the same effect on the carburizing process and is suitable for the conventional carbonitriding treatment process.
Detailed Description
The present invention will be described in further detail with reference to examples.
Examples
Example 1
The method for solving the problem of unqualified carbonitriding quality comprises the following steps:
(1) cleaning the workpiece to be treated by using a cleaning agent to remove oil stains and impurities on the surface of the workpiece;
(2) a pretreatment process, namely pretreating the cleaned workpiece to be treated for 0.5h at the temperature of 900 ℃ by using nitrogen as protective atmosphere; reducing the temperature to 840 ℃ within 0.5 h;
(3) and carbonitriding heat treatment: treating the pretreated workpiece by using a mixture of nitrogen, methanol, natural gas and ammonia gas as a medium at 840 ℃, wherein the flow rate of the nitrogen is 2.2m3The flow rate of methanol is 3.3L/h, and the flow rate of ammonia is 0.2m3/h；
(4) And tempering: fully tempering the workpiece subjected to carbonitriding at 180 ℃ for 4 hours;
(5) and quenching: treating the tempered workpiece at 820 ℃ for 1.2 h;
(6) and secondary tempering: and (3) carrying out secondary tempering on the quenched workpiece at 187 ℃, wherein the secondary tempering time is 4 h.
Example 2
The method for solving the problem of unqualified carbonitriding quality comprises the following steps:
(1) cleaning the workpiece to be treated by using a cleaning agent to remove oil stains and impurities on the surface of the workpiece;
(2) a pretreatment process, namely pretreating the cleaned workpiece to be treated for 1.5 hours at the temperature of 910 ℃ by using nitrogen as protective atmosphere; reducing the temperature to 860 ℃ within 0.7 h;
(3) and carbonitriding heat treatment: treating the pretreated workpiece by using a mixture of nitrogen, methanol, natural gas and ammonia gas as a medium at 860 ℃, wherein the flow rate of the nitrogen is 2.8m3The flow rate of methanol is 2.7L/h, and the flow rate of ammonia is 0.4m3/h；
(4) And tempering: fully tempering the workpiece subjected to carbonitriding at 190 ℃ for 5 hours;
(5) and quenching: treating the tempered workpiece at 840 ℃ for 1.5h;
(6) and secondary tempering: and (3) carrying out secondary tempering on the quenched workpiece at 190 ℃, wherein the secondary tempering time is 5 h.
Example 3
The method for solving the problem of unqualified carbonitriding quality comprises the following steps:
(1) cleaning the workpiece to be treated by using a cleaning agent to remove oil stains and impurities on the surface of the workpiece;
(2) a pretreatment process, namely pretreating the cleaned workpiece to be treated for 1h at 915 ℃ by using nitrogen as protective atmosphere; the temperature is reduced to 850 ℃ within 1.5h;
(3) and carbonitriding heat treatment: treating the pretreated workpiece by using a mixture of nitrogen, methanol, natural gas and ammonia gas as a medium at 850 ℃, wherein the flow of the nitrogen is 2.5m3The flow rate of methanol is 3L/h, and the flow rate of ammonia is 0.3m3/h；
(4) And tempering: fully tempering the workpiece subjected to carbonitriding at 192 ℃ for 4 hours;
(5) and quenching: treating the tempered workpiece at 820 ℃ for 1h;
(6) and secondary tempering: and (3) carrying out secondary tempering on the quenched workpiece at 187 ℃, wherein the secondary tempering time is 4 h.
Example 4
The method for solving the problem of unqualified carbonitriding quality comprises the following steps:
(1) cleaning the workpiece to be treated by using a cleaning agent to remove oil stains and impurities on the surface of the workpiece;
(2) a pretreatment process, namely pretreating the cleaned workpiece to be treated for 1h at the temperature of 920 ℃ by using nitrogen as protective atmosphere; the temperature is reduced to 850 ℃ within 1h;
(3) and carbonitriding heat treatment: treating the pretreated workpiece by using a mixture of nitrogen, methanol, natural gas and ammonia gas as a medium at 850 ℃, wherein the flow of the nitrogen is 2.5m3The flow rate of methanol is 3L/h, and the flow rate of ammonia is 0.3m3/h；
(4) And tempering: fully tempering the workpiece subjected to carbonitriding at 200 ℃ for 4 hours;
(5) and quenching: treating the tempered workpiece at 820 ℃ for 1h;
(6) and secondary tempering: and (3) carrying out secondary tempering on the quenched workpiece at 200 ℃, wherein the secondary tempering time is 4 h.
Example 5
The method for solving the problem of unqualified carbonitriding quality comprises the following steps:
(1) cleaning the workpiece to be treated by using a cleaning agent to remove oil stains and impurities on the surface of the workpiece;
(2) a pretreatment process, namely pretreating the cleaned workpiece to be treated for 1h at 930 ℃ by using nitrogen as protective atmosphere; the temperature is reduced to 850 ℃ within 1h;
(3) and carbonitriding heat treatment: treating the pretreated workpiece by using a mixture of nitrogen, methanol, natural gas and ammonia gas as a medium at 850 ℃, wherein the flow of the nitrogen is 2.5m3The flow rate of methanol is 3L/h, and the flow rate of ammonia is 0.3m3/h；
(4) And tempering: fully tempering the workpiece subjected to carbonitriding at 200 ℃ for 4 hours;
(5) and quenching: treating the tempered workpiece at 820 ℃ for 1h;
(6) and secondary tempering: and (3) carrying out secondary tempering on the quenched workpiece at 190 ℃, wherein the secondary tempering time is 4 h.
Example 6
The method for solving the problem of unqualified carbonitriding quality comprises the following steps:
(1) cleaning the workpiece to be treated by using a cleaning agent to remove oil stains and impurities on the surface of the workpiece;
(2) a pretreatment process, namely pretreating the cleaned workpiece to be treated for 1h at 915 ℃ by using nitrogen as protective atmosphere; the temperature is reduced to 850 ℃ within 1h;
(3) and carbonitriding heat treatment: treating the pretreated workpiece by using a mixture of nitrogen, methanol, natural gas and ammonia gas as a medium at 850 ℃, wherein the flow of the nitrogen is 2.5m3The flow rate of methanol is 3L/h, and the flow rate of ammonia is 0.3m3/h；
(4) And tempering: fully tempering the workpiece subjected to carbonitriding at 190 ℃ for 4h;
(5) and quenching: treating the tempered workpiece at 820 ℃ for 1h;
(6) and secondary tempering: and (3) carrying out secondary tempering on the quenched workpiece at 187 ℃, wherein the secondary tempering time is 4 h.
Example 7
The method for solving the problem of unqualified carbonitriding quality comprises the following steps:
(1) cleaning the workpiece to be treated by using a cleaning agent to remove oil stains and impurities on the surface of the workpiece;
(2) a pretreatment process, namely pretreating the cleaned workpiece to be treated for 1h at 915 ℃ by using nitrogen as protective atmosphere; the temperature is reduced to 850 ℃ within 1h;
(3) and carbonitriding heat treatment: treating the pretreated workpiece by using a mixture of nitrogen, methanol, natural gas and ammonia gas as a medium at 850 ℃, wherein the flow of the nitrogen is 2.5m3The flow rate of methanol is 3L/h, and the flow rate of ammonia is 0.3m3/h；
(4) And tempering: fully tempering the workpiece subjected to carbonitriding at 180 ℃ for 3.8 h;
(5) and quenching: treating the tempered workpiece at 800 ℃ for 0.8 h;
(6) and secondary tempering: and (3) carrying out secondary tempering on the quenched workpiece at 180 ℃, wherein the secondary tempering time is 3.5 h.
Comparative example
Reference group made of example 7
Comparative example 1
Comparative example 1 differs from example 7 in that no pretreatment was applied prior to the carbonitriding heat treatment in comparative example 1, and otherwise remains the same as example 7.
Comparative example 2
Comparative example 2 differs from example 7 in that comparative example 2 used the pretreatment process mentioned in the background, and otherwise remains the same as example 2. The specific pretreatment process comprises the following steps: preoxidation is carried out for 1.5h at 450 ℃.
Comparative example 3
Comparative example 3 differs from example 7 in that comparative example 3 was pretreated without nitrogen protection, and otherwise remains the same as example 7.
Comparative example 4
Comparative example 4 differs from example 7 in that the pretreatment process in comparative example 4 was carried out using nitrogen as a protective atmosphere so that the cleaned workpiece to be treated was pretreated at a temperature of 880 c for 1 hour, all otherwise in accordance with example 7.
Comparative example 5
Comparative example 5 differs from example 7 in that the pretreatment process in comparative example 5 was carried out without using a protective atmosphere so that the cleaned workpiece to be treated was pretreated at 840 ℃ for 1 hour, all the other things remaining in accordance with example 7.
Performance test
And processing the workpiece to be processed according to the process methods of the embodiments 1-7 and the comparative examples 1-5 to obtain corresponding samples. The quality of the samples obtained in the examples 1-7 and the comparative examples 1-5 is detected according to the national standard GB/T34889-2017. The surface hardness of three products in the same furnace in each example or each comparative example was measured, three points were measured on the end faces, the depth of the carbonitride compound on each face was measured by cutting the two products, the average values thereof were calculated respectively and recorded in table 1, and the quality of the products was judged by the hardness of the products and the depth of the carbonitride compound.
The technical requirements of the product are as follows: the surface hardness (62-66) HRC, the surface carbon concentration (0.7-0.85)%, the surface nitrogen concentration is more than or equal to 0.20 percent, and the depth of the carbon-nitrogen compound-containing layer is more than or equal to 0.20 mm.
TABLE 1 quality testing table for samples
As can be seen from Table 1, when the workpiece to be treated is subjected to carbonitriding, the carbonitriding heat treatment process of the present invention, i.e., the workpiece to be treated is cleaned first, the cleaned workpiece is subjected to pretreatment, carbonitriding heat treatment, tempering, quenching and secondary tempering, can effectively solve the problem of non-uniform soft spots and a carburized layer of a product, and can improve the quality of a sample to a certain extent. Compared with the detection results of comparative examples 1-5, the hardness uniformity after the improved pretreatment is better, the surface hardness difference is within the range of 1.5HRC, and the uniformity of the product quality is effectively improved. Meanwhile, the depth of the carbon-nitrogen compound layer is uniform, and the carbon-nitrogen compounds in partial products or partial regions of the same product in the comparative example are too shallow due to the fact that grinding processing is needed in the later period of the bearing, and after the carbon-nitrogen compounds are ground off in the later period, the wear resistance of the regions is reduced, early failure is caused, and the service life of the product is finally influenced.
The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.
Claims (5)
1. A method for solving the problem that the carbonitriding quality of a bearing ring is unqualified comprises the following steps: the method comprises the following steps of cleaning, carbonitriding heat treatment, tempering, quenching and secondary tempering, and is characterized in that a pretreatment process is carried out before carbonitriding, and the pretreatment process comprises the following specific steps: pretreating for 0.5-1.5 h at 910-920 ℃, and adopting nitrogen protection in the whole process when the pretreatment process is carried out; after the pretreatment process, continuously keeping the temperature of the product at 910-920 ℃ for 0.5-1.5 h, then reducing the temperature to 840-860 ℃ and carrying out carbonitriding, wherein the treatment temperature during carbonitriding heat treatment is 840-860 ℃.
2. The method for solving the problem of the unqualified carbonitriding quality of the bearing ring according to claim 1, wherein the medium for carrying out the carbonitriding heat treatment comprises nitrogen, methanol, natural gas and ammonia.
3. The method for solving the problem of the unqualified carbonitriding quality of the bearing ring according to claim 2, wherein the flow rate of the nitrogen is 2.5 +/-0.3 m3The flow rate of the methanol is 3 +/-0.3L/h, and the flow rate of the ammonia gas is 0.2-0.4 m3/h。
4. A method for solving the problem of the carbonitriding quality of a bearing ring according to any one of claims 1 to 3, characterized in that the method comprises the steps of:
(1) cleaning the workpiece to be treated by using a cleaning agent;
(2) a pretreatment process, namely pretreating the cleaned workpiece to be treated for 0.5-1.5 hours at the temperature of 910-920 ℃ by using nitrogen as a protective atmosphere; reducing the temperature to 840-860 ℃ within 0.4-0.7 h;
(3) and carbonitriding heat treatment: treating the pretreated workpiece by taking a mixture of nitrogen, methanol, natural gas and ammonia gas as a medium at 840-860 ℃, wherein the flow rate of the nitrogen is 2.5 +/-0.3 m3The flow rate of the methanol is 3 +/-0.3L/h, and the flow rate of the ammonia gas is 0.2-0.4 m3/h；
(4) And tempering: fully tempering the workpiece subjected to carbonitriding treatment at 180-200 ℃ for 3.8-5 h;
(5) and quenching: treating the tempered workpiece at 800-840 ℃ for 0.8-1.5 h;
(6) and secondary tempering: and (3) carrying out secondary tempering on the quenched workpiece at 180-200 ℃, wherein the secondary tempering time is 3.5-5 h.
5. The method for solving the problem of the unqualified carbonitriding quality of the bearing ring according to claim 4, characterized in that the method comprises the following steps:
(1) cleaning the workpiece to be treated by using a cleaning agent;
(2) a pretreatment process, namely pretreating the cleaned workpiece to be treated for 1h at 915 ℃ by using nitrogen as protective atmosphere; reducing the temperature to 850 ℃;
(3) and carbonitriding heat treatment: treating the pretreated workpiece by using a mixture of nitrogen, methanol, natural gas and ammonia gas as a medium at 850 ℃, wherein the flow of the nitrogen is 2.5m3The flow rate of methanol is 3L/h, and the flow rate of ammonia is 0.3m3/h；
(4) And tempering: fully tempering the workpiece subjected to carbonitriding at 200 ℃ for 4 hours;
(5) and quenching: treating the tempered workpiece at 820 ℃ for 1h;
(6) and secondary tempering: and (3) carrying out secondary tempering on the quenched workpiece at 190 ℃, wherein the secondary tempering time is 4 h.
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| CN115233151A (en) * | 2022-06-24 | 2022-10-25 | 重庆市新超力轴承有限公司 | Bearing ring heat treatment method and high-temperature-resistant bearing |
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| CN85109155A (en) * | 1985-12-19 | 1987-06-24 | 大连海运学院 | Multiple strengthening technique for bearing steel workpiece |
| CN102230151A (en) * | 2011-07-20 | 2011-11-02 | 新大洲本田摩托有限公司 | Heat treatment process of metal workpiece |
| CN103993233A (en) * | 2014-04-10 | 2014-08-20 | 扬州大学 | Novel high-service life die-casting mold steel and process method for manufacturing aluminum-magnesium die-casting mold |
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