KR970002092B1 - Method of manufacturing iron powder - Google Patents
Method of manufacturing iron powder Download PDFInfo
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- KR970002092B1 KR970002092B1 KR1019940029115A KR19940029115A KR970002092B1 KR 970002092 B1 KR970002092 B1 KR 970002092B1 KR 1019940029115 A KR1019940029115 A KR 1019940029115A KR 19940029115 A KR19940029115 A KR 19940029115A KR 970002092 B1 KR970002092 B1 KR 970002092B1
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- iron powder
- heat treatment
- temperature
- particles
- iron
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 77
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 14
- 238000000034 method Methods 0.000 claims abstract description 27
- 238000010438 heat treatment Methods 0.000 claims abstract description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 14
- 238000001816 cooling Methods 0.000 claims abstract description 12
- 230000008569 process Effects 0.000 claims abstract description 11
- 239000007921 spray Substances 0.000 claims abstract description 10
- 239000002245 particle Substances 0.000 claims description 20
- 238000000465 moulding Methods 0.000 abstract description 13
- 230000009467 reduction Effects 0.000 abstract description 9
- 239000002994 raw material Substances 0.000 description 9
- 229910000859 α-Fe Inorganic materials 0.000 description 7
- 239000013078 crystal Substances 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- 238000004663 powder metallurgy Methods 0.000 description 5
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 4
- 238000007796 conventional method Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 238000010791 quenching Methods 0.000 description 4
- 230000000171 quenching effect Effects 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000010583 slow cooling Methods 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 238000011946 reduction process Methods 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 235000021355 Stearic acid Nutrition 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 238000000748 compression moulding Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000004332 deodorization Methods 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 description 1
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000008117 stearic acid Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000009692 water atomization Methods 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/14—Treatment of metallic powder
- B22F1/142—Thermal or thermo-mechanical treatment
-
- B22F1/0007—
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
- B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
- B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
- B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
- B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid
- B22F2009/0824—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid with a specific atomising fluid
- B22F2009/0828—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid with a specific atomising fluid with water
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2201/00—Treatment under specific atmosphere
- B22F2201/01—Reducing atmosphere
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2201/00—Treatment under specific atmosphere
- B22F2201/10—Inert gases
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2301/00—Metallic composition of the powder or its coating
- B22F2301/35—Iron
Abstract
Description
제1도는 종래 방법에 따라 제조된 철분말 입자 조직을 나타내는 사진.1 is a photograph showing the iron powder particle structure prepared according to the conventional method.
제2도는 본 발명 방법에 따라 제조된 철분말 입자조직을 나타내는 사진.Figure 2 is a photograph showing the iron powder grain structure prepared according to the method of the present invention.
제3도는 종래 및 본 발명 방법에 따라 제조된 철분말을 사용하여 성형한 성형체에 대한 밀도와 성형압과의 관계를 나타내는 그래프.3 is a graph showing the relationship between the density and the molding pressure for a molded article molded using iron powders prepared according to the conventional method and the present invention.
본 발명은 자동차 또는 가전기내의 복잡한 형상의 부품을 제조시 사용되는 철분말의 제조방법에 관한 것으로서, 보다 상세히는 성형성이 우수한 철분말의 제조방법에 관한 것이다.BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing iron powder for use in manufacturing parts of complex shapes in automobiles or home appliances, and more particularly, to a method for producing iron powder with excellent formability.
분말야금용 원료인 철분말은 자동차 혹은 가전기기내의 복잡한 형상의 부품을 제조하는데 주로 이용되고 있다. 즉 이들 부품 형상을 갖는 금형내에 철분말을 충전시킨후, 압축성형한 다음 얻어지는 성형체를 고온의 로내에서 소결을 행하여 제조한다.Iron powder, which is a raw material for powder metallurgy, is mainly used to manufacture complex shaped parts in automobiles or home appliances. In other words, after the iron powder is filled into the molds having these component shapes, the molded product obtained by compression molding is sintered in a high-temperature furnace to prepare.
이때 분말야금용 원료로 사용되는 금속분말중 철분말은 주로 물분사법(water atomization)으로 제조되는데, 이렇게 물분사법으로 제조되는 철분말은 용융철 상태에서 고압의 물에 의해 분쇄되어 얻어지기 때문에, 급속한 냉각효과에 의해 철분말 입자내에는 매우 경도가 높은 급냉조직이 형성되고, 또한 철분말 입자표면은 분말화 과정에서 산화반응이 진행되어 산화철 피막을 형성하게 된다. 따라서 물분사법으로 제조된 철분말을 분말야금용 원료로 사용하기 위해서는 반드시 산화철 피막을 제거하기 위한 환원처리를 행하여야만 한다.At this time, the iron powder of the metal powder used as the raw material for powder metallurgy is mainly produced by water atomization. Since the iron powder produced by the water spraying method is obtained by being crushed by high pressure water in the molten iron state, Due to the cooling effect, a very hard quenching structure is formed in the iron powder particles, and the surface of the iron powder particles is oxidized during the powdering process to form an iron oxide film. Therefore, in order to use the iron powder prepared by the water spray method as a raw material for powder metallurgy, a reduction treatment must be performed to remove the iron oxide film.
상기 철분말의 환원처리는 환원성 분위기를 갖는 로내에서 행하며, 환원온도는 900-1200℃로 유지하고 환원성 분위기를 위해서 수소 혹은 분해 암모니아 가스를 사용한다. 이러한 환원처리 과정에서 철분말의 산화피막이 제거됨과 동시에 급냉과정에서 형성된 철분말 입자내의 급냉조직도 변화하게 되면서 Fe순도 99% 이상의 순철분말로 제조되게 된다.The reduction of the iron powder is carried out in a furnace having a reducing atmosphere, the reduction temperature is maintained at 900-1200 ℃ and hydrogen or decomposition ammonia gas is used for the reducing atmosphere. As the oxide film of the iron powder is removed during the reduction treatment, the quenching structure in the iron powder particles formed during the quenching process is also changed, and the iron powder is made of pure iron powder having a purity of 99% or more.
한편, 종래의 방법에서는 물분사법으로 제조한 철분말을 1회의 열(환원) 처리과정에서 냉각속도를 제어해줌으로써 입자내 페라이트 결정립의 크기를 제어하였기 때문에 철분말 입자내 페라이트 결정립을 성장시키기 위해서는 냉각과정에서 3℃/min 이하의 매우 느린 속도로 서냉을 시켜 주어야만 한다.On the other hand, in the conventional method, since the size of ferrite grains in the particles is controlled by controlling the cooling rate of the iron powder prepared by the water spray method in one heat (reduction) treatment process, in order to grow the ferrite grains in the iron powder particles, Slow cooling should be given at very slow speeds of less than 3 ° C / min.
그러나, 이와 같이 제조된 종래의 철분말은 그 방법상 환원과정에서 입자내 결정립의 수를 줄이기 위하여 환원후 매우 느린 속도로 냉각을 시키게 되므로 환원공정시간이 장시간 소요되어 생산성을 저하시킨다는 문제점을 갖고 있을 뿐만 아니라, 철분말 입자내의 페라이트 결정립은 철분말 성형시 입자의 소성변형을 일으키는 전위의 이동을 방해하기 때문에 입자내 결정립의 수가 많을수록 철분말의 성형성은 나빠지게 되는 문제점이 있다.However, the conventional iron powder prepared as described above has a problem that the reduction process takes a long time because the cooling is performed at a very slow speed after reduction in order to reduce the number of crystal grains in the particle during the reduction process. In addition, the ferrite grains in the iron powder particles interfere with the shift of dislocations causing plastic deformation of the iron powder, so that the more the number of grains in the particles, the worse the formability of the iron powder.
따라서, 본 발명은 상기와 같은 문제점을 해결하기 위하여 제안된 것으로서 물분사법에 의해 제조되는 철분말에 대한 열처리 과정을 제어하므로서 성형성이 우수한 철분말을 제조하는 방법을 제공하고자 하는데, 그 목적이 있다.Accordingly, the present invention is proposed to solve the above problems, and to provide a method for producing an iron powder having excellent moldability by controlling the heat treatment process for the iron powder produced by the water spray method, the object is .
이하, 본 발명을 설명한다.Hereinafter, the present invention will be described.
본 발명은 통상의 물분사법에 의해 철분말을 제조하는 방법에 있어서, 상기 물분사법으로 얻어진 철분말을 환원 또는 불활성 분위기하에서 900℃ 이상의 온도로 가열하여 유지한 다음 냉각하는 열처리 과정을 2회 이상 실시하는 성형성이 우수한 철분말의 제조방법에 관한 것이다.The present invention provides a method for producing iron powder by a conventional water spray method, wherein the iron powder obtained by the water spray method is heated or maintained at a temperature of 900 ℃ or more under a reducing or inert atmosphere, and then subjected to a heat treatment process of cooling at least twice. It relates to a method for producing iron powder excellent in moldability.
이하, 본 발명에 대하여 상세히 설명한다.EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.
통상 물분사법에 의해 제조되는 철분말의 평균입도는 80-100㎛의 크기를 가지는데, 이 철분말을 분말야금용 원료로 사용하기 위해서는 약 900-1200℃의 온도범위에서 환원성 분위기하에 1회의 열처리를 거치게 된다. 이때 상기 1회의 열처리과정에서 산화피막이 제거되고 철분말내의 탄소가 제거되어 보통 0.01% 이하의 탄소를 함유하게 되지만, 이와 같이 1회의 열처리를 통해 제조되는 철분말 입자내에는 3℃/min정도로 서냉함에도 불구하고 수많은 미세한 페라이트 결정립이 함유하게 된다. 즉, 1회의 열(환원)처리후 얻어지는 철분말 입자내에는 매우 많은 페라이트 결정립들이 형성되어 있기 때문에 성형시 성형체의 밀도를 높이기 위해서는 높은 성형압이 요구된다.In general, the average particle size of the iron powder produced by the water spray method has a size of 80-100 μm. In order to use the iron powder as a raw material for powder metallurgy, one heat treatment is performed under a reducing atmosphere at a temperature range of about 900-1200 ° C. Will go through. At this time, the oxide film is removed during the one heat treatment process and carbon in the iron powder is removed, so that it usually contains less than 0.01% of carbon. However, in the iron powder particles prepared through the one heat treatment, the temperature is about 3 ° C./min. Nevertheless, it contains numerous fine ferrite grains. That is, since a large number of ferrite grains are formed in the iron powder particles obtained after one heat treatment (reduction), high molding pressure is required to increase the density of the molded body during molding.
그러나 분말야금용의 원료로 사용되는 철분말의 경우 낮은 성형압으로 높은 성형체 밀도를 갖게 하는 것이 생산 및 경제적 측면에서 유리하다.However, in the case of iron powder used as a raw material for powder metallurgy, it is advantageous in terms of production and economics to have a high compact density at low molding pressure.
즉, 낮은 성형압에 의해 고밀도 성형체를 얻을 경우에는 철분말이 충전되는 금속 다이(die)의 수명이 연장될 수있으며, 성형체의 금속 다이로부터의 탈취도 용이하게 되어 생산성도 향상될 수 있다.That is, when a high density molded body is obtained by a low molding pressure, the life of the metal die filled with the iron powder can be extended, and deodorization from the metal die of the molded body can be facilitated, thereby improving productivity.
따라서, 본 발명은 철분말의 성형성을 높이기 위하여 열싸이클법에 의한 열처리를 실시하여 철분말 입자내 결정립을 성장시킴으로써 낮은 성형압에서도 높은 성형체 밀도를 갖도록 한 것이다.Therefore, the present invention is intended to have a high compact density even at a low molding pressure by growing the crystal grains in the iron powder particles by heat treatment by the heat cycle method in order to improve the formability of the iron powder.
즉 철분말 입자내 결정립의 수를 1회의 열(환원)시킨후 냉각과정에서 서냉에 의해 성장시키는 것이 아니라 승온과 냉각속도와는 무관한 열싸이클 방법에 의해 성장시켜 줌으로써 생산시간을 단축시킬 뿐 아니라, 또한 많은 량의 철분말을 연속식이 아닌 장입형식의 로를 이용하여 다량 생산할 수 있다는 장점을 갖고 있다.In other words, the number of grains in the iron powder particles is heated (reduced) once and then grown by slow cooling in the cooling process, but not by shortening the production time by growing by heat cycle method irrelevant to the temperature increase and cooling rate. In addition, it has the advantage that a large amount of iron powder can be produced using a charging furnace rather than a continuous type.
이를 위해 본 발명은 종래 방법과 같이 실시되는 1회의 열(환원)처리후 얻어지는 철분말을 환원성 혹은 불활성 가스분위기로 유지되고 있고 로내에서 900℃ 이상에서 일정시간 유지한 후 상온으로 냉각시키므로서 2회 열처리를 실시한다. 이때, 상기 열처리는 900℃ 이상의 온도에서 실시함이 바람직한데, 그 이유는 철분말 입자내에서 상변태를 유발시키기 위함이다. 다시말하면, 1회의 열처리후 얻어지는 0.01% 이하의 탄소를 함유하고 있는 철분말의 경우 상기 열처리 온도는 철분말의 입자 내부의 페라이트 결정립들이 오스테나이트상으로 변태가 일어날 수 있는 최소 온도이다. 그러나, 경제적인 측면에서는 상기 열처리 온도 900-1000℃의 온도범위에서 실시함이 보다 바람직하다.To this end, the present invention maintains the iron powder obtained after the one-time heat (reduction) treatment performed in the same way as the conventional method in a reducing or inert gas atmosphere, and then maintained twice at a temperature of 900 ° C. or higher in the furnace for cooling to room temperature Heat treatment is performed. At this time, the heat treatment is preferably carried out at a temperature of 900 ℃ or more, the reason is to cause phase transformation in the iron powder particles. In other words, in the case of iron powder containing less than 0.01% of carbon obtained after one heat treatment, the heat treatment temperature is a minimum temperature at which ferrite grains inside the particles of the iron powder can be transformed into an austenite phase. However, in terms of economics, it is more preferable to carry out in the temperature range of the heat treatment temperature 900-1000 ℃.
이때, 열처리 유지시간은 철분말 량에 따라 결정되어지나 철분말의 경우 비표면적이 매우 크므로 일반 잉고트 시편에 비해 매우 짧은 시간내에 변태가 일어난다. 또한 본 발명에서는 승온과 냉각속도에 무관하게 철분말을 단지 오스테나이트 영역의 온도인 900℃ 이상에서 균일 유지한 후 상온으로 냉각시키는 과정을 2회 이상 반복해주면 되기 때문에 분무철분의 1회 열처리 과정에서도 서냉을 할 필요가 없다.At this time, the heat treatment holding time is determined according to the amount of iron powder, but because the specific surface area of the iron powder is very large, transformation occurs within a very short time compared to the general ingot specimen. In addition, in the present invention, even if the iron powder is uniformly maintained at 900 ° C. or higher, which is the temperature of the austenitic region, regardless of the temperature and the cooling rate, the process of cooling to room temperature is repeated two or more times. There is no need for slow cooling.
이와 같이 본 발명에 따라 제조되는 철분말은 입자내 결정립의 수가 10개 이하이며 이 철분말을 사용하여 성형시에는 성협압 6tom/cm2에서 7.0g/cm3이상의 성형체 밀도를 얻을 수 있기 때문에 성형성이 우수한 철분말이 제공된다.As described above, the iron powder prepared according to the present invention has 10 or less crystal grains in the particles, and when the iron powder is formed, the molded body density of 7.0 g / cm 3 or more can be obtained at 6 ton / cm 2 of the cooperative pressure. Iron powder with excellent properties is provided.
이하, 본 발명을 실시예를 통하여 구체적으로 설명한다.Hereinafter, the present invention will be described in detail through examples.
[실시예]EXAMPLE
제철소에서 얻어지는 스크랩을 전기유도용해로에서 용해한 다음, 용해된 용융철을 직경이 3.8mm인 오리피스 노즐을 통해 흘린 후, 이 용융금속 줄기에 100-150bar의 수압으로 고압 분사하여 평균입도가 80㎛인 철분말을 제조하였다. 이때 제조된 철분말의 화학조성은 하기 표 1과 같았다.The scrap obtained from the steel mill is melted in an electric induction furnace, and then the molten iron is flowed through an orifice nozzle having a diameter of 3.8 mm, and then sprayed at high pressure with water pressure of 100-150 bar to the molten metal stem with an average particle size of 80 µm. Horses were prepared. The chemical composition of the prepared iron powder was as shown in Table 1.
상기 표 1과 같은 조성을 가진 철분말의 산화피막을 제거하기 위해 상기 철분말을 Ar 분위기하에서 1050℃의 온도로 가열하여 1시간 유지한 다음, 급냉하고, 다시 동일 분위기하에서 900℃의 온도로 가열하여 20분간 유지한 후, 급냉하여 얻어진 철분말 원료를 발명재로 하였다.In order to remove the oxide film of the iron powder having the composition shown in Table 1, the iron powder was heated to a temperature of 1050 ℃ under Ar atmosphere and maintained for 1 hour, then quenched, and again heated to a temperature of 900 ℃ under the same atmosphere After holding for 20 minutes, the iron powder raw material obtained by quenching was used as an invention material.
이때, 분말원료에 대하여 단면 조직을 촬영하고, 그 결과를 제2도에 나타내었다.At this time, the cross-sectional structure of the powder raw material was photographed, and the result is shown in FIG.
또한, 상기 원료에 대한 성형성을 알아보기 위해 단면적이 2cm 인 원통형 다이에 0.8% Zn 스테아린산 윤활제가 첨가된 상기 원료분말을 충진하고 상온에서 유압프레스를 이용하여 성형압을 변하시키면서 성형체를 제조한 다음, 제조된 성형체에 대하여 성형압에 따른 밀도변화를 측정하고 그 결과를 제3도에 나타내었다.In addition, the cross-sectional area of 2cm to determine the formability of the raw material Filling the cylindrical powder with 0.8% Zn stearic acid lubricant added to the raw material powder and preparing a molded body by varying the molding pressure using a hydraulic press at room temperature, and measuring the density change according to the molding pressure for the manufactured molded body The results are shown in FIG.
또한, 비교를 위하여 상기 표 1과 동일한 조성을 갖고 제1도와 같은 조직을 나타내는 철분말(상품명 : 훼가네스 ASC 100.29)을 이용하여 발명재와 동일한 방법으로 성형체를 제조한 후, 이 제조된 성형체에 대하여 성형압에 따른 밀도 변화를 제3도에 나타내었다.In addition, after the molded article was manufactured by the same method as the invention material using an iron powder (trade name: Feganes ASC 100.29) having the same composition as in Table 1 and showing the structure shown in FIG. The density change with the molding pressure is shown in FIG.
제1도에 나타난 바와 같이, 종래의 1회 열처리한 철분말을 미세 연마한 후 4% 나이탈 부식액을 이용하여 부식시킨 다음 관찰한 철분말의 경우에는 철분말 입자내에 매우 많은 페라이트 결정립들이 형성되어, 성형후에는 제3도에 나타난 바와 같이, 발명재에 비하여 성형체가 치밀하지 못함을 알 수 있다.As shown in FIG. 1, in the case of the iron powder observed after fine grinding of the conventional once-heat-treated iron powder using 4% nital corrosion solution, very many ferrite grains are formed in the iron powder particles. After molding, as shown in FIG. 3, it can be seen that the molded body is not as compact as the invention material.
이에 반하여, 제2도에 나타난 바와 같이, 물분사법으로 제조된 철분말을 2회 열처리한 발명재의 경우에는 철분말 내부에 결정립의 수가 10개 이하로 조대한 결정립을 나타내었으며, 이 분말을 이용하여 성형한 후에는 제3도에 나타난 바와 같이, 성형체가 치밀함을 알 수 있었다.On the contrary, as shown in FIG. 2, in the case of the invention material subjected to the heat treatment of the iron powder prepared by the water spraying method twice, the number of crystal grains in the iron powder was coarse with 10 or less coarse grains. After molding, as shown in FIG. 3, the compact was found to be dense.
즉, 동일한 성형압에서 비교해 볼때, 본 발명에 따라 열사이클 처리를 한 철분말의 경우 더 높은 성형체밀도를 보여주고 있었으며, 상기 열처리를 3회 실시하여도 본 발명과 동일한 효과를 나타내었다.That is, when compared at the same molding pressure, the iron powder subjected to the heat cycle treatment according to the present invention showed a higher molded body density, even if the heat treatment three times the same effect as the present invention.
상술한 바와 같이, 본 발명은 물분사법에 의해 제조되는 철분말을 900℃ 이상의 온도로 가열하여 유지한 다음, 냉각하는 열처리 과정을 2회 이상 실시하므로서 철분말의 내부에 10개 이하의 결정립이 형성되어 이 철분말을 이용하여 성형체 제조시 매우 치밀한 성형체가 얻어지는 효과가 있는 것이다.As described above, the present invention maintains the iron powder produced by the water spray method at a temperature of 900 ℃ or more, and then heats the cooling process two or more times to form a crystal grain of less than 10 inside the iron powder This makes it possible to obtain a very compact molded article during the production of the molded article using the iron powder.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019940029115A KR970002092B1 (en) | 1994-11-08 | 1994-11-08 | Method of manufacturing iron powder |
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| KR1019940029115A KR970002092B1 (en) | 1994-11-08 | 1994-11-08 | Method of manufacturing iron powder |
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| KR970002092B1 true KR970002092B1 (en) | 1997-02-22 |
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