KR20030022427A - A High Strength Alloy Steel of Chrome-Molybdene for a Transmission - Google Patents

A High Strength Alloy Steel of Chrome-Molybdene for a Transmission Download PDF

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KR20030022427A
KR20030022427A KR1020010048269A KR20010048269A KR20030022427A KR 20030022427 A KR20030022427 A KR 20030022427A KR 1020010048269 A KR1020010048269 A KR 1020010048269A KR 20010048269 A KR20010048269 A KR 20010048269A KR 20030022427 A KR20030022427 A KR 20030022427A
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alloy steel
weight part
chromium
molybdenum
weight
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KR1020010048269A
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Korean (ko)
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조봉래
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현대자동차주식회사
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Publication of KR20030022427A publication Critical patent/KR20030022427A/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Gears, Cams (AREA)
  • Heat Treatment Of Articles (AREA)

Abstract

PURPOSE: A high strength Cr-Mo alloy steel for transmission gear is provided which reduces cost and extends life span of processing tools, and which is applied to high power transmission gear and shaft by increasing contents of chromium and molybdenum, thereby replacing existing Ni-Cr-Mo alloy steel applied parts. CONSTITUTION: In a Cr-Mo alloy steel, the high strength Cr-Mo alloy steel for transmission gear comprises 1.10 to 1.40 weight parts of Cr, 0.35 to 0.55 Mo weight parts, 0.1 weight part or less of Si, 0.015 to 0.025 weight part of Nb, 0.55 to 0.75 weight part of Mn and 0.015 weight part or less of P for 100 weight parts of alloy steel, wherein physical properties are not improved if content of chromium is less than 1.10 weight part while cost is increased if content of chromium exceeds 1.40 weight part, physical properties are different from those of an existing Cr-Mo alloy steel if content of molybdenum is less than 0.35 weight part while brittleness is increased as molybdenum based carbide is deposited on the grain boundaries if content of molybdenum exceeds 0.55 weight part, an abnormal layer is formed on the surface the alloy steel during decarburization if content of silicon exceeds 0.1 weight part, and niobium that is a crystal grain micronizing element is added to the alloy steel in an amount of 0.015 to 0.025 weight part to prevent coarsening of crystal grains during decarburization.

Description

변속기 기어용 고강도 크롬-몰리브덴 합금강{A High Strength Alloy Steel of Chrome-Molybdene for a Transmission}A High Strength Alloy Steel of Chrome-Molybdene for a Transmission}

본 발명은 변속기 기어용 고강도 크롬-몰리브덴(Cr-Mo) 합금강에 관한 것으로서, 더욱 상세하게는 크롬과 몰리브덴의 함유량을 증가시켜, 종래 니켈-크롬-몰리브덴 합금강 적용 부품에 대체하여 원가절감 및 가공 도구의 수명을 연장하며 고출력 변속기 기어 및 샤프트에 적용 가능하도록 한 변속기 기어용 고강도 크롬-몰리브덴 합금강에 관한 것이다.The present invention relates to high-strength chromium-molybdenum (Cr-Mo) alloy steel for transmission gears, and more particularly, by increasing the content of chromium and molybdenum, cost reduction and processing tools in place of conventional nickel-chromium-molybdenum alloy steel applied parts A high-strength chromium-molybdenum alloy steel for transmission gears that extends the service life and is applicable to high power transmission gears and shafts.

종래 변속기용 합금강으로 많이 사용되는 소재에는 크롬강, 크롬-몰리브덴강, 니켈-크롬-몰리브덴강 등이 있으며, 주로 침탄 열처리를 하여 사용한다. 자동차 변속기 기어의 제조공정을 도 1에 나타내었는데, 각각의 공정에 적합하며, 가격이 싸고, 열처리 후 물성도 우수해야 최적의 합금강 소재로 볼 수 있다.즉, 단조성, 가공성도 우수하고, 가격도 적합하며, 물성(예, 피로성, 충격특성)도 우수해야 한다.Conventionally used alloy steel for transmissions are chromium steel, chromium-molybdenum steel, nickel-chromium-molybdenum steel, etc., mainly used by carburizing heat treatment. The manufacturing process of the transmission gear of the automobile is shown in FIG. 1, which is suitable for each process, and is inexpensive, and has excellent physical properties after heat treatment, so that it can be regarded as an optimal alloy steel material. It should also be suitable and should have good physical properties (eg fatigue, impact properties).

크롬강과 크롬-몰리브덴강은 가격이 저렴하나, 피로성 및 충격성이 우수하지 않아 주로 큰 부하를 받지 않는 기어류에 많이 쓰인다. 반면, 니켈-크롬-몰리브덴강은 니켈함유 때문에 고가이며 가공성이 난이하다는 큰 단점이 있으나, 피로성 및 충격성이 우수하여 큰 부하를 받는 기어류에 적용되고 있다. 일반적으로 기어용 침탄강의 경우 소입성 증대 및 강도, 인성을 높이기 위해 합금원소인 몰리브덴이나 니켈을 첨가하나, 특히, 니켈의 경우 고가이면서 강에 첨가시 가공성을 떨어지게 하는 문제점이 있다. 또한, 니켈이 첨가된 니켈-크롬-몰리브덴강을 적용하는 기어들은 가공시 가공성 난이에 따른 생산성 저하, 가공 도구 수명 단축 등의 문제점이 있다. Chrome steel and chromium-molybdenum steel are inexpensive, but do not have good fatigue and impact It is mainly used for gears that are not heavily loaded. On the other hand, nickel-chromium-molybdenum steel has a large disadvantage of being expensive and difficult to work due to the nickel content, but has been applied to gears subjected to a large load due to its excellent fatigue and impact resistance. In general, in the case of carburized steel for gears, molybdenum or nickel, which is an alloying element, is added to increase the hardenability and increase the strength and toughness. In addition, gears to which nickel-chromium-molybdenum steel to which nickel is added have problems such as reduced productivity and shortened tool life due to difficulty in processing.

따라서, 이상에서 상술한 가공성 문제 뿐만 아니라 원가절감 측면에서도 우수하고, 니켈-크롬-몰리브덴강을 대체할 수 있는 물성 측면에서 대등한 크롬-몰리브덴강의 개발이 필요하였다.Therefore, it is necessary to develop a chromium-molybdenum steel that is excellent not only in terms of workability but also in terms of cost reduction and superior physical properties in place of nickel-chromium-molybdenum steel.

이에 본 발명자는 기어용 침탄강의 제조시 첨가하는 니켈의 고가이면서 강에 첨가시 가공성을 떨어지게 하는 문제점과 니켈-크롬-몰리브덴강을 적용하는 기어들의 가공성 난이에 따른 생산성 저하, 가공 도구 수명 단축 등의 문제점을 해결하기 위하여 연구 노력하였다. 그 결과, 종래 사용되는 크롬-몰리브덴강을 합금설계적으로 보완하여 니켈-크롬-몰리브덴강을 대체할 물성을 가지며 원가절감이 가능한 본 발명을 완성하였다.Therefore, the present inventors have a problem that the nickel is added at the time of manufacturing the carburized steel for gears, and the workability is degraded when added to the steel, and the productivity is reduced due to the difficulty of workability of the gears to which nickel-chromium-molybdenum steel is applied. We tried to solve the problem. As a result, the present invention has complementary the chromium-molybdenum steel conventionally used in alloy design and has completed the present invention having physical properties to replace the nickel-chromium-molybdenum steel and reducing the cost.

따라서, 본 발명은 크롬과 몰리브덴의 함유량을 증가하여 제조한 변속기 기어용 고강도 크롬-몰리브덴 합금강을 제공하는데 그 목적이 있다.Accordingly, an object of the present invention is to provide a high-strength chromium-molybdenum alloy steel for a transmission gear produced by increasing the content of chromium and molybdenum.

도 1은 자동차 변속기 기어의 제조 공정을 나타낸 것이다.1 shows a manufacturing process of an automobile transmission gear.

본 발명은 크롬-몰리브덴 합금강에 있어서, 합금강 100 중량부에 대하여 크롬 1.10 내지 1.40 중량부와 몰리브덴 0.35 내지 0.55 중량부와 규소 0.1 중량부 이하와 탄소, 망간, 인, 황 및 니오븀을 함유하는 변속기 기어용 고강도 크롬-몰리브덴 합금강을 그 특징으로 한다.The present invention relates to a transmission gear in chromium-molybdenum alloy steel, which contains 1.10 to 1.40 parts by weight of chromium, 0.35 to 0.55 parts by weight of molybdenum, 0.1 parts by weight or less of silicon, and carbon, manganese, phosphorus, sulfur, and niobium based on 100 parts by weight of alloy steel. High strength chromium-molybdenum alloy steel.

이와 같은 본 발명을 더욱 상세하게 설명하면 다음과 같다.The present invention will be described in more detail as follows.

본 발명의 크롬-몰리브덴 합금강 제조시 가공성을 향상시키기 위하여 니켈을 첨가하지 않았으며, 대신 물성 부족분은 크롬과 몰리브덴의 함유량을 종래의 크롬-몰리브덴 합금강의 함유량보다 증가하여 보완했다. 크롬-몰리브덴 합금강에서, 합금강 100 중량부에 대하여 크롬은 1.10 내지 1.40 중량부를 함유하며, 이때 그 함유량이 1.10 중량부 미만일 경우 기존 크롬-몰리브덴 합금강의 물성과 상이한 물성으로 물성향상 효과가 없고, 1.40 중량부를 초과하는 경우 원가상승의 효과가 있다. 몰리브덴은 0.35 내지 0.55 중량부를 함유하며, 이때 그 함유량이 0.35 중량부 미만일 경우도 상기한 크롬의 경우와 같이 기존 크롬-몰리브덴 합금강의 물성과 상이하며, 0.55 중량부를 초과하는 경우 몰리브덴계 탄화물이 입계에 석출되어취성이 커지는 문제가 발생한다. 규소는 0.1 중량부 이하로 함유량을 감소하였으며, 이때 그 함유량이 0.1 중량부를 초과하는 경우 침탄시 표면이상층이 발생된다. 또한, 침탄시 결정립 조대화 방지를 위해 결정립 미세화 원소인 니오븀을 0.015 ~ 0.025 중량부 첨가했다.Nickel was not added in order to improve workability in the preparation of the chromium-molybdenum alloy steel of the present invention. Instead, the lack of physical properties increased the content of chromium and molybdenum by increasing the content of the conventional chromium-molybdenum alloy steel. In chromium-molybdenum alloy steel, chromium contains 1.10 to 1.40 parts by weight with respect to 100 parts by weight of alloy steel, and when the content is less than 1.10 parts by weight, the physical properties different from those of the existing chromium-molybdenum alloy steel have no physical property improvement effect, and 1.40 parts by weight In case of exceeding wealth, there is a cost increase effect. Molybdenum contains 0.35 to 0.55 parts by weight, the content of which is less than 0.35 parts by weight is different from the physical properties of the existing chromium-molybdenum alloy steel as in the case of the above chromium, and when it exceeds 0.55 parts by weight molybdenum-based carbide Precipitation causes a problem of large brittleness. The content of silicon is reduced to 0.1 parts by weight or less, and when the content exceeds 0.1 parts by weight, an abnormal surface layer is generated during carburization. Further, in order to prevent grain coarsening during carburization, 0.015 to 0.025 parts by weight of niobium, which is a grain refinement element, was added.

이하, 본 발명을 실시예 및 비교예에 의하여 더욱 상세하게 설명하는 바, 본 발명이 이하 실시예 및 비교예에 의하여 한정되는 것은 아니다.Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited by the following Examples and Comparative Examples.

실시예 및 비교예Examples and Comparative Examples

본 발명의 실시예 및 비교예의 합금 성분의 구성은 다음 표 1과 같다. 다음 표 1에 나타낸 바와 같이 합금성분의 구성성분과 함량을 사용하여 통상의 방법으로 실시예 및 비교예를 제조하였다.The composition of the alloy component of the Examples and Comparative Examples of the present invention is shown in Table 1. As shown in Table 1, Examples and Comparative Examples were prepared by conventional methods using the components and contents of the alloying components.

실험예Experimental Example

본 발명의 실시예 및 비교예의 피로성 및 충격특성 시험결과를 다음 표 2에 나타내었다.Fatigue and impact characteristics test results of Examples and Comparative Examples of the present invention are shown in Table 2 below.

시험조건은 동일하며, 열처리(900℃, 2시간 침탄), 오일 소입(오일온도: 150℃), 템퍼링(170℃, 2시간)의 순서로 시행했다.The test conditions were the same, and heat treatment (900 ° C., 2 hours carburizing), oil quenching (oil temperature: 150 ° C.), and tempering (170 ° C., 2 hours) were performed in this order.

상기 표 2에 나타낸 바와 같이, 본 발명에 따른 실시예의 크롬-몰리브덴 합금강의 물성은 비교예인 니켈-크롬-몰리브덴 합금강과 대등한 수준을 나타냄을 알 수 있었다.As shown in Table 2, the physical properties of the chromium-molybdenum alloy steel of the embodiment according to the present invention was found to show a level comparable to that of the comparative nickel-chromium-molybdenum alloy steel.

이상에서 상술한 바와 같이, 본 발명의 변속기 기어용 크롬-몰리브덴 합금강은 니켈-크롬-몰리브덴강 적용 부품에 대체 가능하고, 고출력 변속기 기어 및 샤프트에 적용 가능하여 원가절감 및 가공 도구의 수명을 연장하는 효과가 있다.As described above, the chromium-molybdenum alloy steel for the transmission gear of the present invention can be replaced with nickel-chromium-molybdenum steel applied parts, and can be applied to high-power transmission gears and shafts to reduce cost and extend the life of machining tools. It works.

Claims (1)

크롬-몰리브덴 합금강에 있어서, 합금강 100 중량부에 대하여 크롬 1.10 내지 1.40 중량부, 몰리브덴 0.35 내지 0.55 중량부, 규소 0.1 중량부 이하, 니오븀 0.015 ~ 0.025 중량부, 망간 0.55 ∼ 0.75 중량부, 인 0.015 중량부 이하, 몰리브덴 0.35 ∼ 0.55중량부를 함유하는 변속기 기어용 고강도 크롬-몰리브덴 합금강In the chromium-molybdenum alloy steel, 1.10 to 1.40 parts by weight of chromium, 0.35 to 0.55 parts by weight of molybdenum, 0.1 parts by weight or less of silicon, 0.015 to 0.025 parts by weight of niobium, 0.55 to 0.75 parts by weight of manganese, and 0.015% by weight of chromium-molybdenum alloy steel High-strength chromium-molybdenum alloy steel for transmission gears containing 0.35 to 0.55 parts by weight of molybdenum or less
KR1020010048269A 2001-08-10 2001-08-10 A High Strength Alloy Steel of Chrome-Molybdene for a Transmission KR20030022427A (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02170916A (en) * 1988-12-22 1990-07-02 Kobe Steel Ltd Manufacture of gear blank having stepped through hole
JPH0488148A (en) * 1990-07-30 1992-03-23 Kobe Steel Ltd High strength gear steel capable of rapid carburization and high strength gear
JPH0570924A (en) * 1991-09-17 1993-03-23 Nippon Steel Corp Method for carburizing heat treatment of high strength gear small in strain and the gear

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02170916A (en) * 1988-12-22 1990-07-02 Kobe Steel Ltd Manufacture of gear blank having stepped through hole
JPH0488148A (en) * 1990-07-30 1992-03-23 Kobe Steel Ltd High strength gear steel capable of rapid carburization and high strength gear
JPH0570924A (en) * 1991-09-17 1993-03-23 Nippon Steel Corp Method for carburizing heat treatment of high strength gear small in strain and the gear

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