CN1143743C - A manufacturing method of high-density powder metallurgy valve seat - Google Patents
A manufacturing method of high-density powder metallurgy valve seat Download PDFInfo
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- CN1143743C CN1143743C CNB001073346A CN00107334A CN1143743C CN 1143743 C CN1143743 C CN 1143743C CN B001073346 A CNB001073346 A CN B001073346A CN 00107334 A CN00107334 A CN 00107334A CN 1143743 C CN1143743 C CN 1143743C
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- 238000004663 powder metallurgy Methods 0.000 title claims abstract description 11
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 10
- 239000000843 powder Substances 0.000 claims abstract description 23
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 16
- 239000000956 alloy Substances 0.000 claims abstract description 16
- 238000000034 method Methods 0.000 claims abstract description 16
- 238000010438 heat treatment Methods 0.000 claims abstract description 13
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 11
- 239000010439 graphite Substances 0.000 claims abstract description 11
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 10
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 6
- 238000009692 water atomization Methods 0.000 claims abstract description 4
- 230000000754 repressing effect Effects 0.000 claims description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 229910052742 iron Inorganic materials 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 239000002245 particle Substances 0.000 claims description 3
- 230000007935 neutral effect Effects 0.000 claims description 2
- 238000005470 impregnation Methods 0.000 claims 1
- 229910001566 austenite Inorganic materials 0.000 abstract description 5
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical group C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 abstract description 4
- 239000000446 fuel Substances 0.000 abstract description 3
- 238000012360 testing method Methods 0.000 description 10
- 238000003825 pressing Methods 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000009826 distribution Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000005275 alloying Methods 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 238000005242 forging Methods 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000000889 atomisation Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 229910001567 cementite Inorganic materials 0.000 description 1
- 230000008645 cold stress Effects 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000008642 heat stress Effects 0.000 description 1
- 150000002611 lead compounds Chemical class 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 230000001050 lubricating effect Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000011812 mixed powder Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
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Abstract
一种高密度粉末冶金气门座的制造方法，采用水雾化方法制取的含化合碳的予合金粉末。予合金粉末经压制、烧结，制得予烧结坯。将予烧结坯浸渍石墨酒精溶液后置于加热炉中加热，再放入预热至200-300℃的模具中，在奥氏体+渗碳体组织状态下进行热复压，制得汽车发动机气门座。其密度达到7.5g/cm2以上，硬度达到HRC30以上，既耐磨耐热又耐冲击，适合排气温度高、使用无铅燃料甚至无液压挺柱的汽车发动机排气门座的工作环境。A method for manufacturing a high-density powder metallurgy valve seat, using a prealloyed powder containing combined carbon prepared by a water atomization method. The pre-alloy powder is pressed and sintered to obtain a pre-sintered billet. Immerse the pre-sintered body in graphite alcohol solution, heat it in a heating furnace, put it into a mold preheated to 200-300°C, and carry out hot recompression under the state of austenite + cementite structure to obtain an automobile engine valve seat. Its density reaches above 7.5g/cm 2 , and its hardness reaches above HRC30. It is wear-resistant, heat-resistant and impact-resistant. It is suitable for the working environment of exhaust valve seat of automobile engine with high exhaust temperature, unleaded fuel or even no hydraulic tappet.
Description
本发明属于将予合金化粉末进行压制、烧结和热复压，制得汽车零件的冶金领域。适用于汽车发动机配气机构中气门座的生产。The invention belongs to the metallurgical field of making auto parts by pressing, sintering and hot repressing pre-alloyed powder. It is suitable for the production of valve seats in the valve train of automobile engines.
气门座是汽车发动机配气机构中的重要部件。它不仅受到机械冲击作用，还受到高温(700～850℃)燃烧气体的冲刷、腐蚀、燃烧产物及空气中灰尘磨损作用，热冷应力的交替作用，因此，极易产生变形、烧损，甚至断裂。在使用无铅汽油时，由于缺乏或没有析出铅化物的润滑效果，加剧了早期磨损，气门座尤其是排气门座使用条件更加恶劣。The valve seat is an important part in the valve train of an automobile engine. It is not only subjected to mechanical impact, but also to the erosion and corrosion of high-temperature (700-850°C) combustion gas, the abrasion of combustion products and dust in the air, and the alternating action of heat and cold stress. Therefore, it is easy to deform, burn, and even fracture. When using unleaded gasoline, due to the lack of or no lubricating effect of precipitated lead compounds, the early wear is aggravated, and the service conditions of the valve seat, especially the exhaust valve seat, are even worse.
为了解决上述问题，除了改进发动机阀系配置及其间隙等结构设计外，重要的是改进材料和生产工艺。粉末冶金工艺生产的各种材料气门座正在逐渐取代铸造工艺生产的气门座。In order to solve the above problems, in addition to improving the structural design of the engine valve train configuration and its clearance, it is important to improve materials and production processes. Various material valve seats produced by powder metallurgy process are gradually replacing valve seats produced by casting process.
日本专利平5-80521和中国专利CN1131595A分别介绍了一种粉末冶金气门座制造方法，这两种方法都是采用石墨和多种金属粉末的混合物制造。这种粉末混合方法不易使金属元素混合均匀，特别是石墨和各种金属的比重相差悬殊，更不易混合均匀，使所制得的产品合金元素和所形成的碳化物不易分布均匀。而合金元素的分布不均将直接影响合金的物理机械性能，例如冲击韧性、耐热性等，而碳化物分布不均将直接影响合金的耐磨性能。Japanese Patent Ping 5-80521 and Chinese Patent CN1131595A respectively introduce a powder metallurgy valve seat manufacturing method, both of which are manufactured using a mixture of graphite and various metal powders. This powder mixing method is not easy to mix the metal elements evenly, especially the specific gravity of graphite and various metals is very different, and it is even more difficult to mix evenly, so that the alloy elements and the formed carbides are not easy to distribute evenly. The uneven distribution of alloying elements will directly affect the physical and mechanical properties of the alloy, such as impact toughness, heat resistance, etc., and the uneven distribution of carbides will directly affect the wear resistance of the alloy.
本发明目的在于提供一种高密度粉末冶金气门座的制造方法，通过该方法生产的气门座在无铅燃料发动机中具有优异的耐热、耐磨性能和足够的使用寿命。The purpose of the present invention is to provide a method for manufacturing a high-density powder metallurgy valve seat. The valve seat produced by the method has excellent heat resistance, wear resistance and sufficient service life in a lead-free fuel engine.
为达到上述发明目的，本发明所采用的解决问题的手段是：予先制备包含碳在内的铁基予合金化粉末，同时，在奥氏体+渗碳体组织状态下进行热复压。In order to achieve the purpose of the above invention, the problem-solving means adopted in the present invention are: pre-preparing iron-based pre-alloyed powder containing carbon, and at the same time, performing hot recompression in the state of austenite + cementite structure.
本发明在雾化制粉时即将碳加入合金中，制得含化合碳的铁基予合金粉末，其具体化学成分为(重量％)：Cl.0-2.0，Mo2.5-3.5，Ni1.6-2.6，Co9.5-10.5，Mn≤0.5。予合金化可使金属元素能够均匀分布于合金中，有利提高物理机械性能，特别是Ni、Co等元素在合金中的弥散分布有利提高合金的韧性和耐热性能。而碳在制粉时加入，则有利形成(Fe、Cr、Mo)3C。(Fe、Cr、Mo)3C具有较高的显微硬度，HV达800-900，有利提高合金的耐磨性能。In the present invention, carbon is added into the alloy during atomization powder making to obtain iron-based pre-alloy powder containing combined carbon, and its specific chemical composition is (% by weight): Cl.0-2.0, Mo2.5-3.5, Ni1. 6-2.6, Co9.5-10.5, Mn≤0.5. Pre-alloying can make the metal elements evenly distributed in the alloy, which is beneficial to improve the physical and mechanical properties, especially the dispersed distribution of Ni, Co and other elements in the alloy is beneficial to improve the toughness and heat resistance of the alloy. The addition of carbon during powder making is beneficial to the formation of (Fe, Cr, Mo) 3 C. (Fe, Cr, Mo) 3 C has high microhardness, HV up to 800-900, which is beneficial to improve the wear resistance of the alloy.
但是，合金粉末含有化合碳，使粉末颗粒变硬，成形性大大下降。为了得到高密度粉末冶金气门座，本发明采用了奥氏体+渗碳体组织状态下的热复压工艺。However, the alloy powder contains combined carbon, which makes the powder particles hard and greatly reduces the formability. In order to obtain a high-density powder metallurgy valve seat, the present invention adopts a hot repressing process in the state of austenite + cementite structure.
基于上述考虑，本发明制造方法包括制粉、压制、烧结、热复压等步骤，其特征在于具体步骤为：采用水雾化方法制取含化合碳的铁基予合金粉末，所述予合金粉末颗粒尺寸在0.154mm以下，所述予合金粉末中碳含量为1.0-2.0重量％；予合金粉末以600-800Mpa压力压制，在1100-1150℃、中性气氛中烧结1-1.5小时，制得予烧结坯；将所制得予烧结坯用含2-4重量％石墨的酒精溶液进行浸渍，浸渍时间为1-2分钟，然后进入热复压工序；所述热复压工序为：先将模具预热至200-300℃，再将上述用石墨酒精溶液浸渍过的予烧结坯放入电阻丝加热、氮气保护且予烧结坯可连续移动的加热炉中，在750-1050℃下加热3-5分钟，然后将加热至750-1050℃的予烧结坯置于模具中，以600-800Mpa压力，进行再压制，即可制得高密度粉末冶金气门座。Based on the above considerations, the manufacturing method of the present invention includes steps such as powder making, pressing, sintering, and hot repressing. The particle size of the powder is below 0.154mm, and the carbon content in the pre-alloyed powder is 1.0-2.0% by weight; the pre-alloyed powder is pressed with a pressure of 600-800Mpa, and sintered at 1100-1150°C for 1-1.5 hours in a neutral atmosphere to produce Obtain a pre-sintered compact; impregnate the obtained pre-sintered compact with an alcohol solution containing 2-4% by weight of graphite, and the dipping time is 1-2 minutes, and then enter a thermal re-pressing process; the thermal re-pressing process is: first Preheat the mold to 200-300°C, then put the pre-sintered billet impregnated with graphite alcohol solution into a heating furnace with resistance wire heating, nitrogen protection and continuous movement of the pre-sintered billet, and heat at 750-1050°C After 3-5 minutes, the pre-sintered compact heated to 750-1050°C is placed in the mold, and pressed again with a pressure of 600-800Mpa to obtain a high-density powder metallurgy valve seat.
所获得的粉末冶金气门座，密度＞7.5g/cm3，硬度＞HRC30。The obtained powder metallurgy valve seat has a density > 7.5g/cm 3 and a hardness > HRC30.
与现有技术相比，本发明的优点在于：Compared with the prior art, the present invention has the advantages of:
(1)本发明在水雾化制粉时将石墨加入合金中，制得含化合碳的予合金粉末；其它专利则采用混合粉末。(1) In the present invention, graphite is added into the alloy during water atomization to produce pre-alloyed powder containing combined carbon; other patents use mixed powder.
(2)本发明采用的热复压是在奥氏体+渗碳体双相组织状态下进行热复压；而一般热复压是铁素体或奥氏体单相组织的热复压。(2) The hot repressing adopted in the present invention is to carry out hot repressing under the state of austenite+cementite two-phase structure; and general hot repressing is the hot repressing of ferrite or austenite single-phase structure.
(3)本发明热复压所用加热装置是电阻丝加热的普通加热炉，造价低；而象气门座这样的小件样品一般热复压或热锻所采用的加热手段是中频感应加热，设备造价高，需要昂贵的中频控制装置。(3) The heating device used for hot repressing of the present invention is a common heating furnace heated by resistance wire, and the cost is low; and the heating means adopted for hot repressing or hot forging of small samples such as valve seats is intermediate frequency induction heating, and the equipment The cost is high and an expensive intermediate frequency control device is required.
(4)本发明样品加热炉可通氮气等保护气体，可防止加热氧化，防止产生氧化物夹杂；而一般感应加热是在空气中进行的，样品容易氧化，容易产生氧化物夹杂。(4) The sample heating furnace of the present invention can pass protective gases such as nitrogen to prevent heating oxidation and oxide inclusions; while general induction heating is carried out in air, samples are easily oxidized and oxide inclusions are easily generated.
(5)本发明样品在热复压前，先浸渍含2-4％石墨的酒精溶液，使样品表面均匀地布敷一薄层石墨，不仅在加热过程，而且在样品从炉中取出到装入复压模具，即样品在空气里移动过程中可进一步防止氧化和脱碳；而一般热复压或热锻均是在模具上涂敷石墨水溶液，只起润滑作用，起不到上述作用。(5) The sample of the present invention is dipped in an alcohol solution containing 2-4% graphite before hot repressing, so that the surface of the sample is evenly coated with a thin layer of graphite, not only during the heating process, but also when the sample is taken out from the furnace to load Recompression mold, that is, the sample can be further prevented from oxidation and decarburization during the process of moving in the air; while general hot recompression or hot forging is coated with graphite aqueous solution on the mold, which only acts as a lubricant and cannot achieve the above effects.
实施例Example
按本发明所述的制造方法，分别制造了三批高密度粉末冶金排气门座，具体为首先采用水雾化方法制备了予合金粉，其具体化学成分见表1，再将予合金粉通过压制、烧结、热复压制得排气门座，具体的工艺参数见表2，所制得的排气门座的密度及硬度见表3，按照超速耐久实验规范，将上述3批排气门座先在试验台架上全速全负荷(额定转速4200r/min、额定功率72KW、最大扭矩200N·m)运行100小时，然后按表4所列程序6个工况顺序进行超速耐久试验，每个循环为12小时30分，进行了10个循环125小时试验。According to the manufacturing method of the present invention, three batches of high-density powder metallurgy exhaust valve seats have been produced respectively, specifically for first adopting the water atomization method to prepare pre-alloy powder, and its specific chemical composition is shown in Table 1, and then the pre-alloy powder Exhaust valve seats were obtained by pressing, sintering, and heat repressing. The specific process parameters are shown in Table 2. The density and hardness of the prepared exhaust valve seats are shown in Table 3. According to the specifications of the overspeed durability test, the above three batches of exhaust The door seat is first run on the test bench at full speed and full load (rated speed 4200r/min, rated power 72KW, maximum torque 200N m) for 100 hours, and then carry out the overspeed endurance test according to the sequence of 6 working conditions listed in Table 4. One cycle is 12 hours and 30 minutes, and 10 cycles of 125-hour tests were carried out.
按上述试验程序总计进行了225小时台架试验，经拆机检测，三批排气门座尺寸全部在公差范围之内，未见磨损，没有气门下沉，使用情况良好。A total of 225 hours of bench tests were carried out according to the above test procedures. After dismantling and testing, the dimensions of the three batches of exhaust valve seats were all within the tolerance range, with no wear and valve sinking, and the service condition was good.
试验所用汽油机无液压挺柱，没有间隙调节器，气门落座时拍击力大，而且排气温度较高，为850±10℃，使用条件相当恶劣。用同一条件试验的其它几种材料的排气门座，在试验到50-60小时时，气门都有不同程度的下沉。上述试验结果表明，本发明气门座具有优异的耐热、耐磨、耐冲击性能，特别适合排气温度高、使用无铅燃料甚至无液压挺柱的汽车发动机排气门座的工作环境。The gasoline engine used in the test has no hydraulic tappet, no lash adjuster, strong slapping force when the valve is seated, and high exhaust temperature of 850±10°C, so the operating conditions are quite harsh. With the exhaust valve seats of several other materials tested under the same conditions, the valves all sink in different degrees when the test reaches 50-60 hours. The above test results show that the valve seat of the present invention has excellent heat resistance, wear resistance and impact resistance, and is especially suitable for the working environment of the exhaust valve seat of an automobile engine with high exhaust temperature, unleaded fuel or even no hydraulic tappet.
表1实施例排气门座的具体化学成分(重量％)The concrete chemical composition (weight %) of exhaust valve seat of table 1 embodiment
表2实施例所采用的本发明制造方法的具体工艺参数The specific process parameter of the manufacturing method of the present invention that the embodiment of table 2 adopts
表3实施例所制得的排气门座的具体密度及硬度指标Concrete density and hardness index of the exhaust valve seat made by the embodiment of table 3
表4试验工况
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Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1986116B (en) * | 2005-12-19 | 2011-01-19 | 北京有色金属研究总院 | RE-containing pre-alloy powder |
| US8257462B2 (en) * | 2009-10-15 | 2012-09-04 | Federal-Mogul Corporation | Iron-based sintered powder metal for wear resistant applications |
| CN102120262B (en) * | 2011-04-26 | 2013-03-06 | 常熟市双月机械有限公司 | Valve retainer |
| CN102205416B (en) * | 2011-05-19 | 2013-08-28 | 东睦新材料集团股份有限公司 | Manufacture method of engine tappet |
| CN103357863B (en) * | 2013-06-21 | 2016-12-28 | 安徽吉思特智能装备有限公司 | A kind of High abrasion resistant metallurgy valve seat and preparation method thereof |
| CN104480405A (en) * | 2014-12-29 | 2015-04-01 | 常熟市双月机械有限公司 | Hold-down sintered material for valve retainer |
| CN105149571A (en) * | 2015-08-31 | 2015-12-16 | 苏州莱特复合材料有限公司 | Powder metallurgy valve seat and preparation method thereof |
| CN106077660B (en) * | 2016-06-15 | 2018-04-17 | 威海双鑫金属制品有限责任公司 | A kind of method that powder metallurgy prepares engine valve seat |
| CN108817375A (en) * | 2018-07-23 | 2018-11-16 | 重庆智博粉末冶金有限公司 | The powder metallurgy production method and valve retainer of high-performance valve retainer |
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