CN109252133B - Process method for improving surface quality of quenched and tempered steel nitriding part - Google Patents
Process method for improving surface quality of quenched and tempered steel nitriding part Download PDFInfo
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- CN109252133B CN109252133B CN201811327887.XA CN201811327887A CN109252133B CN 109252133 B CN109252133 B CN 109252133B CN 201811327887 A CN201811327887 A CN 201811327887A CN 109252133 B CN109252133 B CN 109252133B
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
- C23C8/24—Nitriding
- C23C8/26—Nitriding of ferrous surfaces
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- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
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- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
Abstract
The invention relates to the technical field of heat treatment processes, in particular to a process method for improving the surface quality of a hardened and tempered steel nitriding part, which specifically adopts a preoxidation three-stage rapid nitriding process and comprises three stages of hard nitriding, namely strong penetration, diffusion and adjustment nitrogen supplement. The nitrogen concentration on the surface of the workpiece is improved by strong permeation in a nitriding environment with low ammonia decomposition rate; the nitrogen is diffused in the nitriding environment with high ammonia decomposition rate, so that the nitride accumulation on the surface is avoided; the decomposition rate and temperature of ammonia gas are reduced, and the nitrogen concentration on the surface of the workpiece is adjusted. Through the improvement of the nitriding process, the surface hardness of the workpiece is improved to 650-680HV1, the surface brittleness is within 2 grade, and the result of more than 80 percent shows that no obvious brittle cracks exist on the surface of the workpiece.
Description
Technical Field
The invention relates to the field of heat treatment processes, in particular to a process method for improving the surface quality of a hardened and tempered steel nitriding part.
Background
The gas nitriding is a metal heat treatment process which is characterized in that a metal material is placed in a certain medium, and the chemical components and the metallographic structure of the surface of the material are changed through five basic processes of atmosphere formation, adsorption, decomposition, absorption and diffusion so as to control the performance of the material. Heat treatment of metals is an important component in the mechanical manufacturing industry.
The carburized part mainly comprises a shaft and an inner gear ring which are basic workpieces in mechanical transmission, and the performance and the service life of the carburized part directly influence the quality index and the running condition of the whole machine. In the vigorous development of the wind power industry, more and more wind power gear rings are made of hardened and tempered steel 42CrMo and are required to be subjected to nitriding treatment, and the layer depth is required to be more than or equal to 0.5 mm. In order to ensure the deformation, two-stage method and three-stage method nitriding processes are eliminated, but the traditional one-stage method nitriding process is adopted, the hard nitriding time is over 100 hours, the period is long, the efficiency is low, the cost is high, and in addition, the workpiece distortion does not meet the requirement even under the environment of 490-520 ℃ for a long time. The two-stage quick nitriding of pre-oxidation shortens half time, reduces the distortion of a workpiece, but the hardness index is lower, only 580-HV 600HV1 is needed, and the brittleness is often out of standard.
Disclosure of Invention
The invention aims to provide a process method for improving the surface quality of a nitrided piece of quenched and tempered steel, and aims to solve the quality problems that 42CrMo quenched and tempered steel is low in hardness, loose or brittle and the like after being subjected to gas nitriding in the prior art.
In order to achieve the purpose, the invention provides the following technical scheme:
a process for improving the surface quality of the nitrided part of quenched and tempered steel features use of three-stage pre-oxidation method for quick nitriding, which includes three stages of hard nitriding, strong penetration, diffusion and regulation of nitrogen supplement.
The process method for improving the surface quality of the quenched and tempered steel nitriding part, disclosed by the invention, comprises the strong infiltration stage at the temperature of 490-520 ℃ for 15 hours, wherein the ammonia decomposition rate is 18-25%.
The process method for improving the surface quality of the quenched and tempered steel nitriding part, disclosed by the invention, comprises the steps of controlling the temperature of the diffusion stage to be 550-570 ℃, controlling the time to be 25h and controlling the ammonia decomposition rate to be 50-60%.
The process method for improving the surface quality of the quenched and tempered steel nitriding part, disclosed by the invention, comprises the steps of regulating the temperature of a nitrogen supplementing stage to be 490-500 ℃, the time to be 5 hours and the ammonia decomposition rate to be 45-50%.
The process method for improving the surface quality of the quenched and tempered steel nitriding part comprises the steps of pre-oxidizing for 1-2 hours at the temperature of 350-450 ℃ before the strong infiltration stage.
Compared with the prior art, the invention has the beneficial effects that:
(1) the process includes three stages of hard nitriding, strong diffusion and nitrogen regulation and supplement. The higher surface hardness is obtained by reasonably adjusting the temperature, time and Kn value in the hard nitriding stage. The process is simple and effectively realizes the effect of improving the surface hardness of the quenched and tempered steel nitriding part; the corrosion resistance and the wear resistance of the nitrided surface are improved.
(2) The prior nitriding process is integrated, so that the preoxidation catalytic gas nitriding is perfected. The quick nitridation process of the pre-oxidation two-stage method is changed into the quick nitridation process of the pre-oxidation three-stage method. The nitrogen concentration on the surface of the workpiece is improved by strong permeation in a nitriding environment with low ammonia decomposition rate; the nitrogen is diffused in the nitriding environment with high ammonia decomposition rate, so that the nitride accumulation on the surface is avoided; the decomposition rate and temperature of ammonia gas are reduced, and the nitrogen concentration on the surface of the workpiece is adjusted. Through the improvement of a nitriding process, the surface hardness of the workpiece is increased to 650-680HV1, the wear resistance of the surface of the workpiece is improved, the surface brittleness is within 2 grades, wherein the result of more than 80% shows that no brittle cracks exist on the surface of the workpiece, the loose improvement enables the nitride layer on the surface of the workpiece to be more compact, and the corrosion resistance of the surface of the workpiece is improved.
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.
Examples
A process for improving the surface quality of the nitrided part of quenched and tempered steel features use of three-stage pre-oxidation method for quick nitriding, which includes three stages of hard nitriding, strong penetration, diffusion and regulation of nitrogen supplement. Wherein, the pre-oxidation is performed for 1-2h before the strong permeation stage, and the temperature is 350-450 ℃. The temperature of the strong permeation stage is 490-520 ℃, the time is 15h, and the ammonia decomposition rate is 18-25%. The temperature of the diffusion stage is 550-570 ℃, the time is 25h, and the ammonia decomposition rate is 50-60%. The temperature of the nitrogen supplementing stage is regulated to be 490-500 ℃, the time is 5 hours, and the ammonia decomposition rate is 45-50%.
To highlight the beneficial effects of the process of the present invention, the following comparative experiments were also conducted, see table 1 for details.
TABLE 1 comparison of specific processes
The results of the comparative experiments are shown in table 2.
TABLE 2 comparison of results
After the process is adopted, the surface hardness of the workpiece is increased to 650-680HV1, the wear resistance of the surface of the workpiece is improved, the surface brittleness is within 2 grades, wherein the result that more than 80 percent shows that the surface of the workpiece has no brittle cracks, the loosening is improved, so that the nitride layer on the surface of the workpiece is more compact, and the corrosion resistance of the surface of the workpiece is improved.
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 (1)
1. A process method for improving the surface quality of quenched and tempered steel nitriding parts is characterized by comprising the following steps: the quenched and tempered steel nitriding part is 42CrMo quenched and tempered steel, and a rapid nitriding process by adopting a pre-oxidation three-stage method specifically comprises three stages of hard nitriding, namely strong penetration, diffusion and nitrogen adjustment and supplement; pre-oxidizing for 1-2h at 350-450 ℃ before the strong infiltration stage; the temperature of the strong permeation stage is 490-520 ℃, the time is 15h, and the ammonia decomposition rate is 18-25%; the temperature of the diffusion stage is 550-570 ℃, the time is 25h, and the ammonia decomposition rate is 50-60%; the temperature of the nitrogen-supplementing stage is regulated to be 490-500 ℃, the time is 5h, and the ammonia decomposition rate is 45-50%.
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| CN201811327887.XA CN109252133B (en) | 2018-11-09 | 2018-11-09 | Process method for improving surface quality of quenched and tempered steel nitriding part |
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| CN109252133B true CN109252133B (en) | 2020-12-08 |
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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 |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001011597A (en) * | 1999-06-28 | 2001-01-16 | Dowa Mining Co Ltd | Gas carburizing nitriding method |
| WO2009153244A1 (en) * | 2008-06-19 | 2009-12-23 | Centro Sviluppo Materiali S.P.A. | Process and plant for producing in situ ammonia-based mixtures with controlled nitriding power |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102168275A (en) * | 2011-04-02 | 2011-08-31 | 上海电机学院 | Heat treatment technology for improving the surface hardness of precise rolling ball bearing |
| CN105714238A (en) * | 2014-12-04 | 2016-06-29 | 重庆聆益机械有限公司 | Pre-oxidation rapid nitriding process for heavy-duty gear |
| CN105779928A (en) * | 2014-12-13 | 2016-07-20 | 重庆环德科技有限公司 | Nitriding heat treatment process for 38CrMoAlA |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001011597A (en) * | 1999-06-28 | 2001-01-16 | Dowa Mining Co Ltd | Gas carburizing nitriding method |
| WO2009153244A1 (en) * | 2008-06-19 | 2009-12-23 | Centro Sviluppo Materiali S.P.A. | Process and plant for producing in situ ammonia-based mixtures with controlled nitriding power |
Non-Patent Citations (1)
| Title |
|---|
| 短时渗氮工艺的研究;胡明娟等;《金属热处理》;19970525(第5期);第3-6页 * |
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