JPS61174324A - Production of high strength steel member capable of easily relieving strain - Google Patents
Production of high strength steel member capable of easily relieving strainInfo
- Publication number
- JPS61174324A JPS61174324A JP1403185A JP1403185A JPS61174324A JP S61174324 A JPS61174324 A JP S61174324A JP 1403185 A JP1403185 A JP 1403185A JP 1403185 A JP1403185 A JP 1403185A JP S61174324 A JPS61174324 A JP S61174324A
- Authority
- JP
- Japan
- Prior art keywords
- steel
- quenching
- steel member
- case hardening
- heat treatment
- 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.)
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Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、歪矯正の容易な高強度鋼部材の製造方法に関
し、詳しくは、浸炭焼入処理、浸炭浸窒焼入処理等の熱
処理後に優れた強度と靭性を有するとともに、焼入処理
に伴う熱処理歪の機械加工による歪矯正を容易とするこ
とのできる歪矯正の容易な高強度鋼部材の製造方法にか
かる。[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing high-strength steel members that can be easily strain-corrected. The present invention relates to a method for manufacturing a high-strength steel member that has excellent strength and toughness, and can easily correct strain caused by heat treatment due to quenching treatment by machining.
従来、自動車部品等においては、その強度と靭性を確保
するため焼入焼もどしの、いわゆる、調質熱処理を施し
て使用するものが多い。Conventionally, many automobile parts and the like have been subjected to so-called refining heat treatment, ie, quenching and tempering, in order to ensure their strength and toughness.
また、歯車等の強度と耐摩耗ｊ生の要求される部品にお
いては、浸炭焼入処理、浸炭浸窒焼入処理等の表面硬化
熱処理を施して使用されるものも少なくない。Furthermore, for parts such as gears that require strength and wear resistance, there are many parts that are used after being subjected to surface hardening heat treatment such as carburizing and quenching, carburizing and nitriding and quenching.
とりわけ、浸炭焼入処理や浸炭浸窒焼入処理は、鋼部材
の耐摩耗性や疲労強度等の向上を目的として各種自動車
部品に広く通用されている。In particular, carburizing and quenching treatments and carbo-nitriding and quenching treatments are widely used in various automobile parts for the purpose of improving the wear resistance, fatigue strength, etc. of steel members.
しかしながら、浸炭焼入処理や浸炭浸窒焼入処理を施し
た鋼部材の表面硬さはＨＶ６００〜８５０という高硬度
となることから、このような熱処理を施した後における
切削・研削加工等の機械加工は極めて困難となる。However, since the surface hardness of steel parts subjected to carburizing and quenching treatments is as high as HV600 to 850, it is difficult to use machines for cutting, grinding, etc. after such heat treatment. Processing becomes extremely difficult.
加えて、鋼部材の焼入処理には焼入変態及び熱応力に起
因する熱処理歪の発生が不可避であるにもかかわらず、
焼入処理後において機械加工により歪矯正を実施するこ
とは上述のような理由から極めて困難である。In addition, although the quenching treatment of steel members inevitably causes heat treatment distortion due to quenching transformation and thermal stress,
For the reasons mentioned above, it is extremely difficult to straighten the strain by machining after the hardening process.
従って、要求精度が厳しく熱処理歪の発生し易い大物複
雑形状部材（例えば、クランクシャフト等）に対する浸
炭焼入処理もしくは浸炭浸窒焼入処理の通用は実用上の
観点からすると極めて困難なものとされていた。Therefore, from a practical point of view, it is extremely difficult to apply carburizing and quenching or carbo-nitriding and quenching to large, complex-shaped members (such as crankshafts) that have strict precision requirements and are prone to heat treatment distortion. was.
また、小物であっても研削もしくは研磨による歪矯正に
は限界があることから、製造された部品の精度の悪化に
基づいて部品性能が低下したり、また、熱処理歪を少な
く熱処理しようとする場合には、焼入処理時において外
力による歪強制熱処理（例えば、プレスクエンチ処理、
プラグ焼入処理等）を導入することが必要となり、熱処
理工程における生産性の低下が避けられないのが現状で
あった。In addition, since there is a limit to distortion correction by grinding or polishing even for small items, part performance may deteriorate due to deterioration of the precision of manufactured parts, and when heat treatment is attempted to reduce heat treatment distortion. For example, strain forced heat treatment by external force during quenching (for example, press quench treatment,
At present, it is necessary to introduce a plug hardening treatment, etc., and a decrease in productivity in the heat treatment process is unavoidable.
〔発明が解決しようとする問題点〕
上述のような従来の技術の現状に鑑み、本発明が解決し
ようとする問題点は、従来の低合金肌焼用鋼を用いた高
強度鋼部材の製造方法においては、浸炭焼入処理もしく
は浸炭浸窒焼入処理された鋼部材の表面硬さが著し′く
高硬度となるとともに、複雑形状部材に適用すると大き
な熱処理歪を発生し、その後における外力による歪矯正
や切削・研削加工等の機械加工による歪矯正が困難とな
り、また、予め熱処理時における熱処理歪の発生を防止
するための歪強制焼入処理においては、熱処理工程にお
ける生産性の低下が避けられないということである。[Problems to be Solved by the Invention] In view of the current state of the conventional technology as described above, the problems to be solved by the present invention are the production of high-strength steel members using conventional low alloy case hardening steel. In this method, the surface hardness of steel parts subjected to carburizing and quenching treatment or carburizing and nitriding and quenching treatment becomes extremely high, and when applied to complex-shaped members, large heat treatment distortions are generated, and external forces are applied afterward. Strain correction by machining such as cutting and grinding becomes difficult, and in forced strain quenching treatment to prevent the occurrence of heat treatment distortion in advance during heat treatment, productivity decreases in the heat treatment process. It is unavoidable.
従って、本発明の技術的課題とするところは、低合金肌
焼用鋼の組成及び熱処理工程を改善することにより、浸
炭焼入処理もしくは浸炭浸窒焼入処理後の鋼部材の表面
部に、熱処理条件によりコントロール可能な厚さを有し
被削性に優れた軟質層を形成させるとともに、その下部
には浸炭焼入処理もしくは浸炭浸窒焼入処理による高硬
度層を形成させることによって、焼入処理後における表
面部の被削性を優れたものとして機械加工による歪矯正
を容易とし、複雑形状であるために熱処理歪が大きくな
り易く精度の確保が難しいことから、現状の浸炭焼入処
理もしくは浸炭浸窒焼入処理の適用が困難とされている
鋼部材（例えば、クランクシャフトカムシャフト等）に
対しても、機械加工による歪矯正の適用を可能とし、も
って、このような複雑形状の鋼部材の強度、耐摩耗性を
飛ＸＮ的に向上させることにある。Therefore, the technical problem of the present invention is to improve the composition and heat treatment process of low-alloy case hardening steel so that the surface of the steel member after carburizing and quenching treatment or carbonitriding and quenching treatment has the following properties: By forming a soft layer with excellent machinability and a thickness that can be controlled by heat treatment conditions, and forming a hard layer below it by carburizing and quenching or carbonitriding and quenching, The current carburizing and quenching process has excellent machinability on the surface after input treatment, making it easy to straighten distortion by machining, but because the shape is complex, heat treatment distortion tends to increase, making it difficult to ensure accuracy. Alternatively, it is possible to apply strain correction by machining to steel parts for which it is difficult to apply carbo-nitriding and quenching (for example, crankshafts, camshafts, etc.). The objective is to significantly improve the strength and wear resistance of steel members.
このような従来の技術における問題点に鑑み、本発明に
おける従来の技術の問題点を解決するための手段は、重
量比率にて、Ｔｉ；０．０１〜０．１％、Ａｌ；０．０
２〜０．５％のうち少なくとも１種類を含有するととも
に、窒素含有量を１００ ｐｐｍ以下とした低合金肌焼
用鋼を用いて、
浸炭処理もしくは浸炭浸窒処理によって、前記低合金肌
焼用鋼からなる鋼部材の表面部に多量のＴｉＮもしくは
ＡＩＮを析出させ、ついで、前記低合金肌焼用鋼の変態
点以下の温度まで冷却し、その後、再加熱して適切な焼
入温度にて保持した後、急冷して焼入処理することを特
徴とする歪矯正の容易な高強度鋼部材の製造方法からな
っている。In view of the problems in the conventional technology, the present invention provides a means for solving the problems in the conventional technology, in which Ti: 0.01 to 0.1% and Al: 0.0% in weight ratio.
Using a low-alloy case-hardening steel containing at least one type from 2 to 0.5% and having a nitrogen content of 100 ppm or less, the low-alloy case-hardening steel is subjected to carburizing treatment or carbo-nitriding treatment. A large amount of TiN or AIN is precipitated on the surface of a steel member made of steel, then cooled to a temperature below the transformation point of the low alloy case hardening steel, and then reheated to an appropriate quenching temperature. The method of manufacturing a high-strength steel member, which is easy to straighten distortion, is characterized in that after being held, it is rapidly cooled and hardened.
以下、本発明の作用について説明する。 Hereinafter, the effects of the present invention will be explained.
本発明において用いる低合金肌廃用鋼の組成を重量比率
にて、’ｌ’ｉ；０．０１〜０．１％、Ａｌ；０゜０２
〜０．５％のうち少なくとも１種類を含有するとともに
、窒素含有量を１００ ｐｐｍ以下としているのは、浸
炭焼入処理もしくは浸炭浸窒焼入処理によって、鋼部材
の表面部に多量のＴｉＮもしくはＡＩＮを析出させて、
浸炭焼入もしくは浸炭浸窒焼入のための再加熱保持時に
おいて、鋼部材の表面部におけるオーステナイト結晶粒
径の成長を抑制するためである。The composition of the low-alloy skin waste steel used in the present invention is as follows: 'l'i: 0.01 to 0.1%, Al: 0°02
-0.5% and the nitrogen content is 100 ppm or less because a large amount of TiN or By precipitating AIN,
This is to suppress the growth of austenite crystal grain size in the surface portion of the steel member during reheating and holding for carburizing and quenching or carbo-nitriding and quenching.
また、本発明において、浸炭処理もしくは浸炭浸窒処理
した後、低合金肌焼用鋼の変態点以下の温度まで冷却し
、さらに、再加熱して適切な焼入温度にて保持した後、
急冷して焼入処理することとしているのは、上述のよう
な組成を有する低合金肌焼用鋼を用いることにより、鋼
の焼入性がオーステナイト結晶粒径の影響を大きく受け
ることを利用して、浸炭焼入処理もしくは浸炭浸窒焼入
処理によって鋼部材の表面部に多量のＴｉＮもしくはＡ
ＩＮを析出させた後、適切な焼入温度にて保持する熱処
理時において、鋼部材のオーステナイト結晶粒径を表面
部で細粒、内部で粗粒に調整することによって、焼入処
理後における鋼部材の表面部のみに対して焼入性を低下
させて硬度の低い非マルテンサイト組ｉ（パーライト組
織もしくはトルースタイト組織）とし、鋼部材の軟質な
表面部の内部においては、通常の浸炭焼入処理もしくは
浸炭浸窒焼入処理により得られるものと同程度の高硬度
の高炭素マルテンサイト組織とするためである。In addition, in the present invention, after carburizing or carburizing/nitriding, cooling to a temperature below the transformation point of the low alloy case hardening steel, and then reheating and holding at an appropriate quenching temperature,
The reason for rapid cooling and quenching is that by using a low-alloy case hardening steel with the above-mentioned composition, the hardenability of the steel is greatly affected by the austenite grain size. Then, a large amount of TiN or A is deposited on the surface of the steel member by carburizing and quenching or carbo-nitriding and quenching.
After IN is precipitated, the austenite crystal grain size of the steel member is adjusted to be fine at the surface and coarse at the inside during heat treatment, which is maintained at an appropriate quenching temperature. The hardenability of only the surface part of the steel member is reduced to form a non-martensitic structure with low hardness (pearlite structure or troostite structure), and the inside of the soft surface part of the steel member is subjected to normal carburizing and quenching. This is to obtain a high-carbon martensitic structure with a hardness comparable to that obtained by treatment or carbo-nitriding and quenching.
以下、添付図面に基づいて、本発明の１実施例を説明す
る。Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.
まず、重量比率にて、０．３％Ｃ’ −０，６％Ｍ ｎ
−０，２５％５ｉ−０，２％Ｃｒ−０，２４％Ａｌ−
０，００２３％Ｂ−０．００５％Ｎ−Ｂａ１Ｆｅからな
る組成の低合金肌焼用鋼の鋼部材を用いて、熱処理とし
て９５０’ＣＸ３００ｍ１ｎのガス浸炭焼入処理を実施
した後、一旦、低合金肌焼用鋼の変態点以下の温度に冷
却し、ついで、８５０°ＣＸ ４０ ｍｉｎの浸炭焼入
温度における加熱保持（細粒化処理）を実施した後、マ
ルテンパ油中に浸漬して油焼入した。First, in terms of weight ratio, 0.3%C' -0.6%M n
-0,25%5i-0,2%Cr-0,24%Al-
Using a steel member of low alloy case hardening steel with a composition of 0,0023%B-0.005%N-Ba1Fe, after performing gas carburizing and quenching treatment of 950'CX300ml as heat treatment, the low alloy It is cooled to a temperature below the transformation point of case hardening steel, then heated and maintained at a carburizing and quenching temperature of 850°C for 40 min (grain refining treatment), and then immersed in martempering oil and oil quenched. did.
上記低合金肌焼用鋼を用いて上述の熱処理を実施した鋼
部材の表面部におけるＡ Ｉ Ｎ濃度分布。A I N concentration distribution in the surface portion of a steel member subjected to the above-described heat treatment using the above-mentioned low-alloy case hardening steel.
旧オーステナイト結晶粒径の顕微鏡写真、硬さ分布１表
面部金属組織の顕微鏡写真をそれぞれ第１図〜第４図に
示している。A micrograph of the prior austenite crystal grain size and a micrograph of the metal structure of the hardness distribution 1 surface area are shown in FIGS. 1 to 4, respectively.
ガス浸炭処理時における吸窒により鋼部材の表面部には
多量のＡＩＮが析出し、そのＡＩＮが上記低合金肌焼用
鋼の変態点以下に冷却後、焼入処理のための再加熱保持
時における表面部のオーステナイト結晶粒径の成長を抑
制して、鋼部材の内部に比較して鋼部材の表面部は極め
て焼入性の低い状態となり、この焼入性の差を焼入後の
組織（マルテンサイト組織及びパーライト組織）の違い
とすることができるのである。A large amount of AIN precipitates on the surface of the steel member due to nitrogen absorption during gas carburizing treatment, and after the AIN is cooled to below the transformation point of the above-mentioned low-alloy case hardening steel, during reheating and holding for quenching treatment. By suppressing the growth of the austenite crystal grain size on the surface of the steel member, the surface of the steel member has extremely low hardenability compared to the inside of the steel member, and this difference in hardenability is reflected in the microstructure after quenching. (martensitic structure and pearlite structure).
その後、適切な冷却媒（この場合マルテンパ油）に焼入
することによって、第２図及び第４図に示すような層状
組織の明確なパーライト組織からなる表面軟化層ａを形
成させることができるとともに、鋼部材の内部において
はＨＶ７００以上を有する高硬度の浸炭焼入組織（マル
テンサイト組織）からなる硬化層すとなっている。Thereafter, by quenching in an appropriate cooling medium (in this case, martempering oil), it is possible to form a surface softening layer a consisting of a clear pearlite structure with a layered structure as shown in FIGS. 2 and 4. Inside the steel member, there is a hardened layer consisting of a highly hard carburized and quenched structure (martensitic structure) having an HV of 700 or more.
また、この実施例においては約０．３ ｔｍの表面軟化
層ａを形成させているが、表面軟化層ａの厚さは浸窒処
理条件（雰囲気成分、温度１時間等）、浸炭焼入のため
の再加熱条件、焼入条件等により任意に制御することが
可能である。In addition, in this example, a surface softening layer a of approximately 0.3 tm is formed, but the thickness of the surface softening layer a depends on the nitriding treatment conditions (atmospheric components, temperature for 1 hour, etc.), carburizing and quenching conditions, etc. It is possible to arbitrarily control the temperature by adjusting the reheating conditions, quenching conditions, etc.
なお、対象とされる鋼部材により強度、耐摩耗性等の材
料特性を確保のために表面軟化層ａを除去することが必
要とされる場合もあるが、軟質層であることから機械加
工により容易に除去することが可能である。Depending on the target steel member, it may be necessary to remove the surface softening layer a in order to ensure material properties such as strength and wear resistance, but since it is a soft layer, it may be necessary to remove it by machining. It can be easily removed.
以上により明らかなように、本発明にかかる歪矯正の容
易な高強度鋼部材の製造方法によれば、低合金肌焼用鋼
の組成及び熱処理工程を改善することにより、浸炭焼入
処理もしくは浸炭浸窒焼入処理後の鋼部材の表面部に、
熱処理条件によりコントロール可能な厚さを有し被削性
に優れた軟質層を形成させるとともに、その内部には浸
炭焼入処理もしくは浸炭浸窒焼入処理による高硬度層を
形成させることによって、焼入処理後における表面部の
被削性を優れたものとして機械加工による歪矯正を容易
とし、複雑形状であるために熱処理歪が大きくなり易く
精度の確保が難しいことから、現状の浸炭焼入処理もし
くは浸炭浸窒焼入処理の通用が困難とされている鋼部材
（例えば、クランクシャフトカムシャフト等）に対して
も、機械加工による歪矯、正の通用を可能とし、もって
、このような複雑形状の鋼部材の強度、耐摩耗性を飛躍
的に向上させること′ができる利点・がある。As is clear from the above, according to the method of manufacturing a high-strength steel member that is easy to straighten strain according to the present invention, by improving the composition and heat treatment process of low-alloy case hardening steel, carburizing and quenching or carburizing On the surface of the steel member after nitriding and quenching,
By forming a soft layer with excellent machinability and a thickness that can be controlled by heat treatment conditions, and forming a high-hardness layer inside it by carburizing and quenching or carbonitriding and quenching, The current carburizing and quenching process has excellent machinability on the surface after input treatment, making it easy to straighten distortion by machining, but because the shape is complex, heat treatment distortion tends to increase, making it difficult to ensure accuracy. Alternatively, it is possible to straighten and correct distortions by machining even steel parts for which it is difficult to apply carbo-nitriding and quenching (for example, crankshafts, camshafts, etc.). It has the advantage of dramatically improving the strength and wear resistance of shaped steel members.
第１図は鋼部材の表面部におけるＡＩＮ濃度の分布を示
す図。
第２図は、鋼部材の表面部における旧オーステナイト結
晶粒径の分布を示す金属組織の顕微鏡写真。
第３図は、鋼部材の表面部における硬さ分布を示す図。
第４図は、鋼部材の裏面部金属組織の顕微鏡写真を示す
図である。
ａ・・−−−一表面軟化層。
ｂ−・−・硬化層。
出願人 トヨタ自動車株式会社
表面いらの距禽ｔ（ＪＴｌｍ）
第１図
第３図
゛ 第４図
手続補正書（自発）
昭和６０年７り／ノ日FIG. 1 is a diagram showing the distribution of AIN concentration on the surface of a steel member. FIG. 2 is a micrograph of the metallographic structure showing the distribution of prior austenite crystal grain sizes on the surface of a steel member. FIG. 3 is a diagram showing the hardness distribution on the surface of a steel member. FIG. 4 is a diagram showing a microscopic photograph of the metallographic structure of the back surface of the steel member. a...---One surface softening layer. b---hardened layer. Applicant: Toyota Motor Corporation (JTlm) Figure 1 Figure 3 ゛ Figure 4 Procedural Amendment (Voluntary) July 1985/No.
Claims (1)
０．０２〜０．５％のうち少なくとも１種類を含有する
とともに、窒素含有量を１００ｐｐｍ以下とした低合金
肌焼用鋼を用いて、 浸炭処理もしくは浸炭浸窒処理によって、前記低合金肌
焼用鋼からなる鋼部材の表面部に多量のＴｉＮもしくは
ＡＩＮを析出させ、ついで、前記低合金肌焼用鋼の変態
点以下の温度まで冷却し、その後、再加熱して適切な焼
入温度にて保持した後、急冷して焼入処理することを特
徴とする歪矯正の容易な高強度鋼部材の製造方法。[Claims] 1. In terms of weight ratio, Ti; 0.01 to 0.1%, Al;
Using a low alloy case hardening steel containing at least one type from 0.02 to 0.5% and having a nitrogen content of 100 ppm or less, the low alloy case hardening is carried out by carburizing treatment or carbo-nitriding treatment. A large amount of TiN or AIN is precipitated on the surface of a steel member made of working steel, then cooled to a temperature below the transformation point of the low alloy case hardening steel, and then reheated to an appropriate quenching temperature. 1. A method for producing a high-strength steel member that is easy to straighten distortion, the method comprising holding the member in the same position as the steel member, followed by rapid cooling and quenching.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1403185A JPS61174324A (en) | 1985-01-28 | 1985-01-28 | Production of high strength steel member capable of easily relieving strain |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1403185A JPS61174324A (en) | 1985-01-28 | 1985-01-28 | Production of high strength steel member capable of easily relieving strain |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS61174324A true JPS61174324A (en) | 1986-08-06 |
Family
ID=11849782
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1403185A Pending JPS61174324A (en) | 1985-01-28 | 1985-01-28 | Production of high strength steel member capable of easily relieving strain |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61174324A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004104245A3 (en) * | 2003-05-20 | 2005-07-07 | Exxonmobil Res & Eng Co | Composition gradient cermets and reactive heat treatment process for preparing same |
| US7431777B1 (en) | 2003-05-20 | 2008-10-07 | Exxonmobil Research And Engineering Company | Composition gradient cermets and reactive heat treatment process for preparing same |
-
1985
- 1985-01-28 JP JP1403185A patent/JPS61174324A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004104245A3 (en) * | 2003-05-20 | 2005-07-07 | Exxonmobil Res & Eng Co | Composition gradient cermets and reactive heat treatment process for preparing same |
| US7431777B1 (en) | 2003-05-20 | 2008-10-07 | Exxonmobil Research And Engineering Company | Composition gradient cermets and reactive heat treatment process for preparing same |
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