CN114293139A - Low-temperature soft nitriding process - Google Patents
Low-temperature soft nitriding process Download PDFInfo
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- CN114293139A CN114293139A CN202111480986.3A CN202111480986A CN114293139A CN 114293139 A CN114293139 A CN 114293139A CN 202111480986 A CN202111480986 A CN 202111480986A CN 114293139 A CN114293139 A CN 114293139A
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Abstract
The invention discloses a low-temperature soft nitriding process, which comprises the following process flows: s1, selecting a gas nitriding treatment furnace, and adding a nitrogen, ammonia and carbon dioxide penetrating agent into the nitriding treatment furnace; s2, workpiece blank quenching and tempering pretreatment: the workpiece has good comprehensive mechanical property; s3, cleaning and cleaning the workpiece blank to ensure the surface to be clean; s4, preheating, and controlling the heat preservation time to be 40-60 minutes; s5, transferring the preheated workpiece to a gas nitriding treatment furnace for soft nitriding; s6, carrying out soft nitriding and then cooling; the invention selects the nitrogen, ammonia and carbon dioxide permeating agent as the nitriding gas medium, strictly controls the dripping proportion, can ensure that the workpiece has better comprehensive mechanical properties (hardness, wear resistance, fatigue strength and corrosion resistance) after nitriding, and is used for automatically controlling the atmosphere and nitrogen potential of the permeating agent by arranging the hydrogen probe in the nitriding furnace, thereby being safe and environment-friendly.
Description
Technical Field
The invention relates to the technical field of heat treatment processes, in particular to a low-temperature soft nitriding process.
Background
The alloy is gradually used for industrial production from the 50 th of the 20 th century, and carbon steel, low alloy steel, tool and die steel, stainless steel, cast iron and iron-based powder metallurgy materials can be processed as the alloy is not limited by steel types; the obtained infiltrated layer has higher tissue hardness, obviously improves the fatigue strength, the wear resistance and the corrosion resistance of the workpiece, and has the performances of scratch resistance, occlusion resistance and the like under the dry friction condition; the heat treatment and the machining are not needed after the workpiece is treated; the wear-resistant steel plate has the advantages of small deformation and the like, and is widely applied to workpieces which bear light and medium loads and have certain wear resistance requirements on the surface, such as dies, measuring tools, cutters, shaft pins, gears, cylinder sleeves, mechanical structural parts and the like.
The soft nitriding is one of the commonly used metal heat treatment processes, and is generally divided into two processes of gas soft nitriding in a gas medium and liquid soft nitriding in a salt bath according to the different forms and methods of adopted penetrants, the process principle of the gas soft nitriding is to heat and preserve heat a steel workpiece in an active nitrogen and carbon medium, so that nitrogen and carbon simultaneously permeate into the surface of the workpiece, namely nitrocarburizing, mainly nitriding, and obtain a dense and high-chemical-stability nitrocarbide layer and a surface inward diffusion layer on the surface layer of the workpiece, and the surface hardness of the workpiece after the common carbon steel and low-alloy steel co-nitriding treatment is lower than that of nitriding, so the workpiece is conventionally called soft nitriding.
In fact, the hardness, the carburized structure, etc. of the workpiece after soft nitriding are related to the material and the soft nitriding process thereof, and in order to obtain better mechanical properties (hardness, wear resistance, fatigue strength, corrosion resistance) of the metal workpiece, a low-temperature soft nitriding process needs to be developed in order to meet some requirements that the center of the workpiece after soft nitriding still maintains high quenched and tempered hardness.
Disclosure of Invention
The present invention is directed to a low temperature soft nitriding process to solve the above problems.
In order to achieve the purpose, the invention provides the following technical scheme: a low-temperature soft nitriding process comprises the following process flows:
s1, selecting a gas nitriding treatment furnace with the volume of 600 multiplied by 1200 and the maximum treatment capacity of the gas soft nitriding treatment furnace of 600 kilograms per furnace, adding a nitrogen + ammonia + carbon dioxide penetrating agent into the nitriding treatment furnace according to the material quality of a workpiece, technical requirements and equipment characteristics, and arranging a hydrogen probe in the furnace for automatically controlling the atmosphere and the nitrogen potential of the penetrating agent, so that the furnace is safe and environment-friendly;
s2, workpiece blank quenching and tempering pretreatment: putting a workpiece blank needing nitriding into a quenching furnace; quenching and tempering the workpiece blank by the quenching and high-temperature tempering (at 500-650 ℃) process to improve the strength and toughness of the workpiece, so that the workpiece has good comprehensive mechanical properties and tissue preparation is made for soft nitriding;
s3, cleaning and cleaning the workpiece blank, cooling the quenched and tempered workpiece blank, and cleaning by adopting an oil stain removal cleaning solution and rinsing by adopting an antirust solution to remove oil stains and rust stains on the surface of the workpiece and ensure that the surface is clean;
s4, preheating, namely, putting the cleaned workpiece into a preheating furnace for preheating, wherein the preheating temperature is controlled to be 300-450 ℃, and the heat preservation time is controlled to be 40-60 minutes;
s5, transferring the preheated workpiece to a gas nitriding treatment furnace for tufftriding, wherein the tufftriding temperature is lower than the conventional temperature by 20-50 ℃, the tufftriding temperature is adjusted to 530-540 ℃ (aiming at structural steel workpieces such as 40Cr and the like), and the tufftriding period is as follows: the depth of the co-permeation layer and the co-permeation time are in a parabolic relation, the co-permeation layer deepens along with the time extension, and the soft nitriding period time is correspondingly prolonged by 1-2 hours to ensure that the co-permeation depth and the like meet the requirements;
s6, carrying out soft nitriding and cooling: after soft nitriding, the workpiece is generally cooled rapidly to enable the co-permeation layer to rapidly form nitrogen-containing martensite so as to achieve high surface hardness, the nitrided workpiece can be immersed in oil for cooling and rapid water circulation cooling outside the furnace (air cooling in a hearth) in a common mode, the cooling time is generally 0.5-1 h, and the workpiece is cooled in the furnace to be below 100 ℃ and discharged.
Preferably, the purity of each gas medium introduced in the process is as follows: nitrogen (purity is more than or equal to 99.999%); ammonia (purity is more than or equal to 99.9%); carbon dioxide gas (purity is more than or equal to 99.9%).
Preferably, the process can be used for the soft nitriding production of any one or more of 40Cr, ZG40Cr, 35CrMo, 42CrMo and 40CrMnMo alloy structural steel workpieces.
Preferably, the ventilation volume of nitrogen, ammonia and carbon dioxide in the process is 2-3 times of the volume of the hearth of the nitriding treatment furnace.
Preferably, the metal antirust liquid selected in the process is prepared by using a film forming substance, a corrosion inhibition antirust agent and an antioxidant as main raw materials, and can achieve the effects of rust prevention and oxidation resistance on the surface of a workpiece.
Preferably, the gas medium selected in the process is: nitrogen, ammonia gas and carbon dioxide, wherein the atmosphere of each penetrating agent is added into the nitriding treatment furnace according to the dropping amount ratio of 55:5: 40.
Preferably, before the workpiece is subjected to furnace nitriding, the hearth and the charging basket tool need to be kept clean, so that the effect of the workpiece after nitriding is prevented from being influenced.
The invention has the technical effects and advantages that:
by selecting the nitrogen + ammonia + carbon dioxide permeating agent as a nitriding gas medium and strictly controlling the instillation proportion, the workpiece can have better comprehensive mechanical properties (hardness, wear resistance, fatigue strength and corrosion resistance) after nitriding, and meanwhile, the hydrogen probe is arranged in the nitriding furnace so as to be used for automatically controlling the atmosphere and the nitrogen potential of the permeating agent, so that the nitriding furnace is safe and environment-friendly.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
A low-temperature soft nitriding process comprises the following process flows:
s1, selecting a gas nitriding treatment furnace with the volume of 600 multiplied by 1200 and the maximum treatment capacity of the gas soft nitriding treatment furnace of 600 kilograms per furnace, adding a nitrogen + ammonia + carbon dioxide penetrating agent into the nitriding treatment furnace according to the material quality of a workpiece, technical requirements and equipment characteristics, and arranging a hydrogen probe in the furnace for automatically controlling the atmosphere and the nitrogen potential of the penetrating agent, so that the furnace is safe and environment-friendly;
s2, workpiece blank quenching and tempering pretreatment: putting a workpiece blank needing nitriding into a quenching furnace; quenching and tempering the workpiece blank by the quenching and high-temperature tempering (at 500-650 ℃) process to improve the strength and toughness of the workpiece, so that the workpiece has good comprehensive mechanical properties and tissue preparation is made for soft nitriding;
s3, cleaning and cleaning the workpiece blank, cooling the quenched and tempered workpiece blank, and cleaning by adopting an oil stain removal cleaning solution and rinsing by adopting an antirust solution to remove oil stains and rust stains on the surface of the workpiece and ensure that the surface is clean;
s4, preheating, namely, putting the cleaned workpiece into a preheating furnace for preheating, wherein the preheating temperature is controlled to be 300-450 ℃, and the heat preservation time is controlled to be 40-60 minutes;
s5, transferring the preheated workpiece to a gas nitriding treatment furnace for tufftriding, wherein the tufftriding temperature is lower than the conventional temperature by 20-50 ℃, the tufftriding temperature is adjusted to 530-540 ℃ (aiming at structural steel workpieces such as 40Cr and the like), and the tufftriding period is as follows: the depth of the co-permeation layer and the co-permeation time are in a parabolic relation, the co-permeation layer deepens along with the time extension, and the soft nitriding period time is correspondingly prolonged by 1-2 hours to ensure that the co-permeation depth and the like meet the requirements;
s6, carrying out soft nitriding and cooling: after soft nitriding, the workpiece is generally cooled rapidly to enable the co-permeation layer to rapidly form nitrogen-containing martensite so as to achieve high surface hardness, the nitrided workpiece can be immersed in oil for cooling and rapid water circulation cooling outside the furnace (air cooling in a hearth) in a common mode, the cooling time is generally 0.5-1 h, and the workpiece is cooled in the furnace to be below 100 ℃ and discharged.
In the first embodiment, the purity of each gas medium introduced in the process is as follows: nitrogen (purity is more than or equal to 99.999%); ammonia (purity is more than or equal to 99.9%); carbon dioxide gas (the purity is more than or equal to 99.9 percent), the process can be used for the soft nitriding production of any one or more workpieces in the types of 40Cr, ZG40Cr, 35CrMo, 42CrMo and 40CrMnMo alloy structural steel workpieces, the ventilation amount of nitrogen, ammonia and carbon dioxide in the process is 2-3 times of the volume of a hearth of a nitriding furnace, and the gas medium selected in the process is as follows: nitrogen, ammonia gas and carbon dioxide, wherein the atmosphere of each penetrating agent is added into the nitriding treatment furnace according to the dropping amount ratio of 55:5: 40.
In the second embodiment, the metal antirust liquid selected in the process is prepared by using a film forming substance, a corrosion inhibition antirust agent and an antioxidant as main raw materials, the antirust and antioxidant effects on the surface of a workpiece can be achieved, and before the workpiece is placed into a furnace for nitriding, a hearth and a charging basket tool need to be kept clean, so that the effect of the workpiece after nitriding is prevented from being influenced.
In conclusion, the low-temperature soft nitriding process provided by the invention has the advantages that the nitrogen, ammonia and carbon dioxide penetrating agents are selected as nitriding gas media, the dripping proportion is strictly controlled, so that a workpiece can have better comprehensive mechanical properties (hardness, wear resistance, fatigue strength and corrosion resistance) after nitriding, and meanwhile, the hydrogen probe is arranged in the nitriding furnace for automatically controlling the atmosphere and nitrogen potential of the penetrating agents, so that the process is safe and environment-friendly.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (7)
1. The low-temperature soft nitriding process is characterized by comprising the following process flows:
s1, selecting a gas nitriding treatment furnace with the volume of 600 multiplied by 1200 and the maximum treatment capacity of the gas soft nitriding treatment furnace of 600 kilograms per furnace, adding a nitrogen + ammonia + carbon dioxide penetrating agent into the nitriding treatment furnace according to the material quality of a workpiece, technical requirements and equipment characteristics, and arranging a hydrogen probe in the furnace for automatically controlling the atmosphere and the nitrogen potential of the penetrating agent, so that the furnace is safe and environment-friendly;
s2, workpiece blank quenching and tempering pretreatment: putting a workpiece blank needing nitriding into a quenching furnace; quenching and tempering the workpiece blank by the quenching and high-temperature tempering (at 500-650 ℃) process to improve the strength and toughness of the workpiece, so that the workpiece has good comprehensive mechanical properties and tissue preparation is made for soft nitriding;
s3, cleaning and cleaning the workpiece blank, cooling the quenched and tempered workpiece blank, and cleaning by adopting an oil stain removal cleaning solution and rinsing by adopting an antirust solution to remove oil stains and rust stains on the surface of the workpiece and ensure that the surface is clean;
s4, preheating, namely, putting the cleaned workpiece into a preheating furnace for preheating, wherein the preheating temperature is controlled to be 300-450 ℃, and the heat preservation time is controlled to be 40-60 minutes;
s5, transferring the preheated workpiece to a gas nitriding treatment furnace for tufftriding, wherein the tufftriding temperature is lower than the conventional temperature by 20-50 ℃, the tufftriding temperature is adjusted to 530-540 ℃ (aiming at structural steel workpieces such as 40Cr and the like), and the tufftriding period is as follows: the depth of the co-permeation layer and the co-permeation time are in a parabolic relation, the co-permeation layer deepens along with the time extension, and the soft nitriding period time is correspondingly prolonged by 1-2 hours to ensure that the co-permeation depth and the like meet the requirements;
s6, carrying out soft nitriding and cooling: after soft nitriding, the workpiece is generally cooled rapidly to enable the co-permeation layer to rapidly form nitrogen-containing martensite so as to achieve high surface hardness, the nitrided workpiece can be immersed in oil for cooling and rapid water circulation cooling outside the furnace (air cooling in a hearth) in a common mode, the cooling time is generally 0.5-1 h, and the workpiece is cooled in the furnace to be below 100 ℃ and discharged.
2. The low-temperature soft nitriding process according to claim 1, wherein the purity of each gas medium introduced in the process is as follows: nitrogen (purity is more than or equal to 99.999%); ammonia (purity is more than or equal to 99.9%); carbon dioxide gas (purity is more than or equal to 99.9%).
3. The low-temperature soft nitriding process of claim 1, wherein the process can be used for soft nitriding production of any one or more of 40Cr, ZG40Cr, 35CrMo, 42CrMo and 40CrMnMo alloy structural steel workpieces.
4. The low-temperature tufftride process of claim 1, wherein the aeration volume of nitrogen, ammonia and carbon dioxide in the process is 2-3 times of the volume of the hearth of the nitriding furnace.
5. The low-temperature tufftride process of claim 1, wherein the metal rust-inhibiting liquid used in the process is prepared from film-forming substances, corrosion-inhibiting rust-inhibiting agents and antioxidants as main raw materials, and can achieve the effects of rust prevention and oxidation resistance on the surface of a workpiece.
6. The low-temperature soft nitriding process according to claim 1, wherein the gas medium selected in the process is: nitrogen, ammonia gas and carbon dioxide, wherein the atmosphere of each penetrating agent is added into the nitriding treatment furnace according to the dropping amount ratio of 55:5: 40.
7. The low-temperature tufftride process of claim 1, wherein before the workpiece is subjected to furnace nitridation, the hearth and the charging basket tool need to be kept clean to prevent the workpiece from being nitrided.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114875213A (en) * | 2022-04-14 | 2022-08-09 | 徐州徐工传动科技有限公司 | Quenching and tempering and nitriding process method for 42CrMo ring gear |
| CN115505844A (en) * | 2022-09-22 | 2022-12-23 | 蒙阴金华机械有限公司 | Die forging and soft nitriding method for mine car wheel |
| CN115572937A (en) * | 2022-10-28 | 2023-01-06 | 西安理工大学 | High-hardness antifriction steel wire ring and preparation method thereof |
| CN115612972A (en) * | 2022-09-27 | 2023-01-17 | 南京丰东热处理工程有限公司 | Steel surface layer thickness controllable nitrogen-containing martensite composite modified layer and process method thereof |
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| CN105369189A (en) * | 2015-11-30 | 2016-03-02 | 太仓久信精密模具股份有限公司 | Nitriding process for H13 die steel |
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| CN102732820A (en) * | 2011-04-10 | 2012-10-17 | 上海上大热处理有限公司 | Gas nitrocarburizing method for automobile brake disc |
| WO2014002120A1 (en) * | 2012-06-26 | 2014-01-03 | Cavina Fulvio Fabrizio | Process and plant for the anti-oxidising surface treatment of steel parts |
| CN104498966A (en) * | 2014-12-05 | 2015-04-08 | 衡阳风顺车桥有限公司 | Process for tufftriding amino gas |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114875213A (en) * | 2022-04-14 | 2022-08-09 | 徐州徐工传动科技有限公司 | Quenching and tempering and nitriding process method for 42CrMo ring gear |
| CN115505844A (en) * | 2022-09-22 | 2022-12-23 | 蒙阴金华机械有限公司 | Die forging and soft nitriding method for mine car wheel |
| CN115505844B (en) * | 2022-09-22 | 2023-06-27 | 蒙阴金华机械有限公司 | Die forging and soft nitriding method for mine car wheels |
| CN115612972A (en) * | 2022-09-27 | 2023-01-17 | 南京丰东热处理工程有限公司 | Steel surface layer thickness controllable nitrogen-containing martensite composite modified layer and process method thereof |
| CN115572937A (en) * | 2022-10-28 | 2023-01-06 | 西安理工大学 | High-hardness antifriction steel wire ring and preparation method thereof |
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