CN114737149A - GCr15轴承碳氮共渗表面改性方法 - Google Patents
GCr15轴承碳氮共渗表面改性方法 Download PDFInfo
- Publication number
- CN114737149A CN114737149A CN202210457164.1A CN202210457164A CN114737149A CN 114737149 A CN114737149 A CN 114737149A CN 202210457164 A CN202210457164 A CN 202210457164A CN 114737149 A CN114737149 A CN 114737149A
- Authority
- CN
- China
- Prior art keywords
- bearing
- carbonitriding
- gcr15
- treatment
- surface modification
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000002715 modification method Methods 0.000 title claims abstract description 10
- CKUAXEQHGKSLHN-UHFFFAOYSA-N [C].[N] Chemical compound [C].[N] CKUAXEQHGKSLHN-UHFFFAOYSA-N 0.000 title description 5
- 238000005256 carbonitriding Methods 0.000 claims abstract description 37
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 28
- 238000000034 method Methods 0.000 claims abstract description 25
- 238000010438 heat treatment Methods 0.000 claims abstract description 14
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 14
- 238000010791 quenching Methods 0.000 claims abstract description 14
- 230000000171 quenching effect Effects 0.000 claims abstract description 14
- 238000010583 slow cooling Methods 0.000 claims abstract description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 3
- 229910052760 oxygen Inorganic materials 0.000 claims description 3
- 239000001301 oxygen Substances 0.000 claims description 3
- 229910052799 carbon Inorganic materials 0.000 claims description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims 1
- 239000000126 substance Substances 0.000 claims 1
- 229910000734 martensite Inorganic materials 0.000 abstract description 12
- 238000005496 tempering Methods 0.000 abstract description 7
- 238000005516 engineering process Methods 0.000 abstract description 6
- 238000004519 manufacturing process Methods 0.000 abstract description 5
- 239000000463 material Substances 0.000 abstract description 5
- 238000001514 detection method Methods 0.000 abstract description 2
- 238000011161 development Methods 0.000 abstract description 2
- 238000012360 testing method Methods 0.000 description 6
- 150000001875 compounds Chemical class 0.000 description 5
- 229910001566 austenite Inorganic materials 0.000 description 4
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 230000002035 prolonged effect Effects 0.000 description 3
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 2
- JMANVNJQNLATNU-UHFFFAOYSA-N oxalonitrile Chemical compound N#CC#N JMANVNJQNLATNU-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910017464 nitrogen compound Inorganic materials 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
Images
Classifications
-
- 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
- C23C8/28—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 more than one element being applied in one step
- C23C8/30—Carbo-nitriding
- C23C8/32—Carbo-nitriding of ferrous surfaces
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/002—Heat treatment of ferrous alloys containing Cr
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/40—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rings; for bearing races
-
- 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
- C23C8/80—After-treatment
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
本发明提供GCr15轴承碳氮共渗表面改性方法，涉及轴承制造领域，包括如下处理工艺：轴承碳氮共渗处理；碳氮共渗后前室氮气保护缓冷处理；轴承二次加热淬火，本发明所提出GCr15轴承碳氮共渗表面改性方法，经检测，轴承表面为细针状马氏体组织，表面硬度达到(62～64)HRC，与传统淬回火工艺相比，其表面耐磨性提高3～4倍，使用寿命提高2倍以上，符合发挥材料极限、节约材料资源、降低污染排放的轴承热处理技术发展方向。
Description
技术领域
本发明涉及轴承制造领域，尤其涉及GCr15轴承碳氮共渗表面改性方法。
背景技术
轴承是装备制造业中重要的、关键的基础零部件，轴承的质量直接决定着重大装备和主机产品的性能、质量和可靠性，被誉为装备制造的“心脏”部件。
我国的轴承热处理起步较晚，但近十年轴承常规热处理发展较快，普通精度和一般寿命的轴承热处理已能完全实现批量生产，传统轴承材料常选用高碳铬轴承钢，热处理工艺基本采用马氏体淬火+低温回火，此种热处理工艺生产的轴承可以满足大部分零件的使用要求，但不能满足使用环境恶劣的产品高耐磨性的要求；为改善目前高耐性轴承加工领域受制于人的现状，提出一种汽车用GCr15轴承碳氮共渗表面改性技术，革新性提高轴承的耐磨性以及综合使用寿命。
发明内容
本发明的目的在于提供GCr15轴承碳氮共渗表面改性方法，以解决采用马氏体淬火+低温回火制造工艺，不能满足使用环境恶劣的产品高耐磨性的技术问题。
本发明为解决上述技术问题，采用以下技术方案来实现：GCr15 轴承碳氮共渗表面改性方法，包括如下处理工艺：
1)轴承碳氮共渗处理；
2)碳氮共渗后前室氮气保护缓冷处理；
3)轴承二次加热淬火。
以下，对上述处理工艺进行说明：
【1】轴承碳氮共渗处理后轴承表面碳氮化合物层，表面硬度达到62～64HRC，与传统淬回火工艺相比，耐磨性提高3～4倍；
【2】碳氮共渗后前室氮气保护缓冷处理是产品碳氮共渗结束前 20分钟，打开前室氮气，降低前室氧含量，并在缓冷过程中，以10L/min 的流量持续通入氮气，基于此，能有效防止缓冷过程中轴承表面脱碳以及碳氮化合物数量减少，甚至出现无碳氮化合物层的现象；
【3】轴承二次加热淬火工艺，获得细针状马氏体组织，解决因碳氮共渗后直接淬火得到粗针状马氏体的问题，提高产品的使用寿命。
本发明的有益效果是：
本发明所提出GCr15轴承碳氮共渗表面改性方法，经检测，轴承表面为细针状马氏体组织，表面硬度达到(62～64)HRC，与传统淬回火工艺相比，其表面耐磨性提高3～4倍，使用寿命提高2倍以上，符合发挥材料极限、节约材料资源、降低污染排放的轴承热处理技术发展方向。
附图说明
图1为本发明GCr15轴承表面金相组织500x的示意图；
图2为本发明GCr15轴承心部金相组织500x的示意图；
具体实施方式
为了使本发明实现的技术手段、创作特征、达成目的与功效易于明白了解，下面结合具体实施例和附图，进一步阐述本发明，但下述实施例仅仅为本发明的优选实施例，并非全部。基于实施方式中的实施例，本领域技术人员在没有做出创造性劳动的前提下所获得其它实施例，都属于本发明的保护范围。
下面结合附图描述本发明的具体实施例。
实施例1
在本实施例中提出了GCr15轴承碳氮共渗表面改性方法，包括如下处理工艺：
1)轴承碳氮共渗处理；
2)碳氮共渗后前室氮气保护缓冷处理；
3)轴承二次加热淬火。
以下，对于上述处理工艺进行说明：
①创新研发了GCr15轴承碳氮共渗技术，产品质量稳定，获得轴承表面碳氮化合物层，表面硬度达到62～64HRC，与传统淬回火工艺相比，耐磨性提高3～4倍，能满足现代汽车工业恶劣工况下的使用要求；
②轴承碳氮共渗结束前20分钟，手动打开前室氮气，降低前室氧含量，并在缓冷过程中，以10L/min的流量持续通入氮气，能有效防止缓冷过程中轴承表面脱碳，从而防止碳氮化合物数量减少，甚至出现无碳氮化合物层有现象，碳氮共渗后缓冷执行工艺参数如表1：
表1
③提出了GCr15轴承碳氮共渗后二次加热淬火工艺，获得细针状马氏体组织，解决了因碳氮共渗后直接淬火得到粗针状马氏体的问题，提高产品的使用寿命，二次加热执行工艺参数见表2：
表2
实施例2
轴承碳氮共渗技术要求，碳氮共渗后表面硬度62～64HRC，碳氮化合物层深0.3～0.5mm，无碳氮化合物层深度≤0.1mm(因热处理后磨削余量在0.1mm以上)；心部硬度60.5～62.5HRC；表面金相组织为含氮马氏体+粒状碳氮化合物+残余奥氏体，心部组织为马氏体+残余奥氏体1～4级。
在本实例中提出一种对GCr15轴承进行耐磨性测试的测试方法，包括对已经通过碳氮共渗表面改性技术处理后的GCr15轴承进行摩擦测试。
1)测试内容包括使用摩擦磨损试验机，以200r/min的转速，对通过碳氮共渗表面改性技术处理后的GCr15轴承进行持续摩擦。
2)试验结果：
①硬度测试结果如下：
表面硬度：62.5、63.0、63.5HRC；
心部硬度：61.0、62.0、61.5HRC。
②金相分析结果如下：
Ⅰ.碳氮化合物层深(0.35～0.40)mm，无碳氮化合物层深度≤ 0.1mm；
Ⅱ.表面组织为含氮细针状马氏体+细小点状碳氮化合物+少量残余奥氏体，如图1所示；
Ⅲ.心部组织为针状马氏体+残余奥氏体，如图2所示。
3)试验结论：
①碳氮共渗层组织，硬度高，强度高，可降低摩擦系数和金属摩擦副的粘附性，从而提高耐磨性和表面疲劳强度；
②与传统淬回火工艺对比，碳氮共渗技术的汽车轴承耐磨性提高 3～4倍，使用寿命提高2倍以上。
以上显示和描述了本发明的基本原理、主要特征和本发明的优点。本行业的技术人员应该了解，本发明不受上述实施例的限制，上述实施例和说明书中描述的仅为本发明的优选例，并不用来限制本发明，在不脱离本发明精神和范围的前提下，本发明还会有各种变化和改进，这些变化和改进都落入要求保护的本发明范围内。本发明要求保护范围由所附的权利要求书及其等效物界定。
Claims (2)
1.GCr15轴承碳氮共渗表面改性方法，其特征在于，包括如下处理工艺：
轴承碳氮共渗处理；
碳氮共渗后前室氮气保护缓冷处理；
轴承二次加热淬火；
其中，
轴承碳氮共渗处理包括向轴承表面同时渗入碳、氮；
碳氮共渗后前室氮气保护缓冷处理包括在轴承碳氮共渗结束前20分钟，打开前室氮气，降低前室氧含量，并在缓冷过程中，持续通入氮气。
2.根据权利要求1所述的GCr15轴承碳氮共渗表面改性方法，其特征在于：所述持续通入氮气的流量为10L/min。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210457164.1A CN114737149A (zh) | 2022-04-27 | 2022-04-27 | GCr15轴承碳氮共渗表面改性方法 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210457164.1A CN114737149A (zh) | 2022-04-27 | 2022-04-27 | GCr15轴承碳氮共渗表面改性方法 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114737149A true CN114737149A (zh) | 2022-07-12 |
Family
ID=82283144
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210457164.1A Pending CN114737149A (zh) | 2022-04-27 | 2022-04-27 | GCr15轴承碳氮共渗表面改性方法 |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114737149A (zh) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN85109155A (zh) * | 1985-12-19 | 1987-06-24 | 大连海运学院 | 轴承钢工件综合强化工艺 |
| JP2006250294A (ja) * | 2005-03-11 | 2006-09-21 | Ntn Corp | 転がり軸受 |
| CN202246831U (zh) * | 2011-10-11 | 2012-05-30 | 祁标 | 密封箱式气体碳氮共渗炉成套设备 |
| CN103237913A (zh) * | 2011-12-06 | 2013-08-07 | 日本精工株式会社 | 滚动轴承及其制造方法 |
| CN110965014A (zh) * | 2019-12-30 | 2020-04-07 | 椿中岛机械（重庆）有限公司 | 一种钢球碳氮共渗工艺 |
| CN112877639A (zh) * | 2021-01-12 | 2021-06-01 | 浙江辛子精工机械有限公司 | 一种高碳铬轴承钢碳氮共渗工艺及设备 |
-
2022
- 2022-04-27 CN CN202210457164.1A patent/CN114737149A/zh active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN85109155A (zh) * | 1985-12-19 | 1987-06-24 | 大连海运学院 | 轴承钢工件综合强化工艺 |
| JP2006250294A (ja) * | 2005-03-11 | 2006-09-21 | Ntn Corp | 転がり軸受 |
| CN202246831U (zh) * | 2011-10-11 | 2012-05-30 | 祁标 | 密封箱式气体碳氮共渗炉成套设备 |
| CN103237913A (zh) * | 2011-12-06 | 2013-08-07 | 日本精工株式会社 | 滚动轴承及其制造方法 |
| CN110965014A (zh) * | 2019-12-30 | 2020-04-07 | 椿中岛机械（重庆）有限公司 | 一种钢球碳氮共渗工艺 |
| CN112877639A (zh) * | 2021-01-12 | 2021-06-01 | 浙江辛子精工机械有限公司 | 一种高碳铬轴承钢碳氮共渗工艺及设备 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5658082A (en) | Rolling contact bearing and a method of producing thereof | |
| JP3909902B2 (ja) | 高耐面圧用鋼部品およびその製造方法 | |
| JP3326874B2 (ja) | 転がり軸受 | |
| JPH0788851B2 (ja) | 転がり軸受 | |
| GB2292389A (en) | Rolling bearing | |
| US20050045248A1 (en) | Contact pressure-resistant member and method of making the same | |
| EP1873409B1 (en) | Rolling/sliding part and production method thereof | |
| CN110965014A (zh) | 一种钢球碳氮共渗工艺 | |
| JPH09257041A (ja) | 表面起点型損傷に強い転がり軸受 | |
| CN111235517A (zh) | 一种金属材料的表面改性方法、金属材料及机械零部件 | |
| US5415705A (en) | Rolling bearing | |
| CN114737149A (zh) | GCr15轴承碳氮共渗表面改性方法 | |
| JPH10204612A (ja) | 機械部品の脱水素処理方法 | |
| CN107119177A (zh) | 透平压缩机用12Cr2Ni4高速齿轮的渗碳淬火表面强化工艺 | |
| JPH05195069A (ja) | 軸受部品の製造方法 | |
| CA1225311A (en) | Cylinder liners | |
| CN85109155A (zh) | 轴承钢工件综合强化工艺 | |
| JP3747075B2 (ja) | 内燃機関用の弁駆動装置におけるカムの滑り面及び又はカム従動子の滑り面を熱化学−熱処理する方法 | |
| CN114686799A (zh) | 金属氮化、氧化然后还原的表面处理方法 | |
| JP2733608B2 (ja) | 軸受用鋼およびその製造方法 | |
| JP2003307223A (ja) | 転がり軸受およびその製造方法 | |
| JPH05118336A (ja) | 転がり軸受 | |
| CN115418552B (zh) | 一种氮碳共渗低合金钢机床摩擦片的制备方法 | |
| CN115261771B (zh) | 一种高温渗碳轴承钢制轴承套圈离子渗氮防渗方法 | |
| KR100336634B1 (ko) | 베어링용 강재의 표층경화 열처리방법 |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |