JPH079026B2 - Composite surface strengthening treatment method - Google Patents
Composite surface strengthening treatment methodInfo
- Publication number
- JPH079026B2 JPH079026B2 JP28190590A JP28190590A JPH079026B2 JP H079026 B2 JPH079026 B2 JP H079026B2 JP 28190590 A JP28190590 A JP 28190590A JP 28190590 A JP28190590 A JP 28190590A JP H079026 B2 JPH079026 B2 JP H079026B2
- Authority
- JP
- Japan
- Prior art keywords
- layer
- nitriding
- steel
- residual stress
- treatment method
- 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.)
- Expired - Lifetime
Links
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- Preventing Corrosion Or Incrustation Of Metals (AREA)
Description
【発明の詳細な説明】 産業上の利用分野 本発明は、鋼材の表面に圧縮残留応力を含む歪硬化層、
その内側に圧縮残留応力をバックアップする窒化等によ
る硬化層、さらにその内部に強靱な組織を持つ強靱化層
の３つの複合層を付与する複合表面強化処理方法に関す
るものであり、静荷重，衝撃荷重および繰返し荷重を受
ける機械要素から金型，工具等に至る広い範囲に利用で
きる。TECHNICAL FIELD The present invention relates to a strain hardening layer containing a compressive residual stress on the surface of a steel material,
The present invention relates to a composite surface strengthening treatment method in which a hardened layer by nitriding or the like for backing up compressive residual stress is provided inside thereof, and three composite layers of a toughened layer having a tough structure are provided inside thereof, static load and impact load. And it can be used in a wide range from mechanical elements that receive repeated loads to dies and tools.
従来の技術 窒化等の表面硬化処理は、従来、単独に用いられ、鋼表
面の耐磨耗性の向上，圧縮応力に対する抵抗増大を目的
としたものであり、それ自身、優れた表面強化処理方法
である。Conventional technology Surface hardening treatment such as nitriding is conventionally used alone, and is aimed at improving the wear resistance of the steel surface and increasing the resistance to compressive stress, and is itself an excellent surface strengthening treatment method. Is.
しかしながら、このような表面強化処理した鋼は、表面
が非常に硬いため、引張応力が作用すると、割れが生じ
易く、表面の微小な切欠きにも感受性が高まる。そのた
め、引張応力成分を含む衝撃荷重や繰返し荷重に対し、
必ずしも大きな抵抗を示さないという欠点がある。However, since the surface of such surface-strengthened steel is extremely hard, when tensile stress acts, cracking is likely to occur and sensitivity to even minute cutouts on the surface increases. Therefore, for impact load and cyclic load including tensile stress component,
It has a drawback that it does not necessarily show a large resistance.
次にオースフォーム等の加工熱処理は、鋼を強化すると
同時に衝撃値等の靱性も改善する効果を持ち、従来、単
独で用いられ、それなりの成果を挙げているものであ
る。Next, thermo-mechanical treatment such as ausform has the effect of strengthening steel and improving toughness such as impact value at the same time, and has been conventionally used alone and has produced some results.
また、ショットピーニング等の噴射加工は、鋼の表面に
歪硬化を生ぜしめると同時に圧縮残留応力を印加し、表
面の微小切欠き等を除去して疲労強度特性の改善に不可
欠の処理技術である。In addition, shot peening and other injection processing is a processing technology that is essential for improving fatigue strength characteristics by producing strain hardening on the surface of steel and simultaneously applying compressive residual stress to remove minute notches and the like on the surface. .
しかしながら、ショットピーニング等によって表面に印
加された圧縮残留応力は、その内部の軟かい層によって
支持されているため、過大応力が作用すると、圧縮残留
応力は容易に消滅し、従ってその効果も失われるという
欠点がある。However, the compressive residual stress applied to the surface by shot peening, etc. is supported by the soft layer inside, so that when excessive stress acts, the compressive residual stress easily disappears, and therefore its effect is also lost. There is a drawback that.
発明が解決しようとする課題 本発明は、窒化等による表面硬化処理の上述の欠点とシ
ョットピーニング等の噴射加工による圧縮残留応力の過
大応力の作用による早期消滅を防止することを目的と
し、さらにオースフォーム等の加工熱処理効果も重畳さ
せて強靱な内部組織を持つ表面組織機構を得る複合表面
強化処理方法を提供することを目的とするものである。DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention aims to prevent early disappearance due to the action of excessive stress of compressive residual stress due to jet processing such as shot peening and the above-mentioned drawbacks of surface hardening treatment by nitriding, etc. It is an object of the present invention to provide a composite surface strengthening treatment method for obtaining a surface texture mechanism having a tough internal texture by superimposing a thermo-mechanical treatment effect on foam and the like.
そして、機械要素類にあっては、疲労強度特性の改善、
また金型および工具類にあっては、隅部あるいは角の部
分に生じる欠け、即ちチッピングの問題を解決しようと
するものである。And in the case of mechanical elements, improvement of fatigue strength characteristics,
Further, the metal mold and the tools are intended to solve the problem of chipping, that is, chipping, which occurs at the corners or corners.
課題を解決するための手段 上記課題を解決するために本発明の複合表面強化処理方
法は、窒化または軟窒化による表面効果処理した鋼をA3
変態点温度以上に加熱し、その温度で塑性加工を行な
い、直ちに焼入れしてマルテンサイト変態を起させ、焼
戻しを施した後、噴射加工を行ない、表面の圧縮残留応
力を持つ歪硬化層、その内側の窒化による硬化層、さら
にその内側の加工熱処理による強靱化層の３つの特性の
異なる表面組織構造を付与することを特徴とするもので
ある。Means for Solving the Problems In order to solve the above-mentioned problems, the composite surface strengthening treatment method of the present invention is applied to a steel surface-treated by nitriding or nitrocarburizing as A 3
Heating above the transformation point temperature, performing plastic working at that temperature, immediately causing quenching to cause martensitic transformation, tempering, then performing injection processing, strain hardening layer with compressive residual stress on the surface, It is characterized by imparting three surface texture structures having different characteristics, namely, a hardened layer by nitriding on the inner side and a toughening layer on the inner side by a heat treatment.
すなわち、鋼の表面に窒化等により硬い薄い層を形成さ
せ、それをA3変態点温度以上に加熱して、そこから塑性
加工を行なって焼入れし、マルテンサイト組織とする。
この時、A3変態点温度以上に加熱する温度と時間によっ
て表面に脱窒素現象が生じ、表面に比較的軟質の薄層が
形成されると同時に、窒化した硬い層が内部に拡散され
る。That is, a hard thin layer is formed on the surface of steel by nitriding or the like, which is heated to a temperature of A 3 transformation point or higher, and plastic working is performed from there to quenching to obtain a martensite structure.
At this time, a denitrification phenomenon occurs on the surface depending on the temperature and time for heating to the A 3 transformation point temperature or higher, and a relatively soft thin layer is formed on the surface, and at the same time, the nitrided hard layer is diffused inside.
また、A3変態点温度以上から鋼を塑性加工して焼入れす
ることによってマルテンサイトが強化される、所謂加工
熱処理効果が重畳する。In addition, a so-called thermomechanical treatment effect, in which martensite is strengthened by plastically working and quenching steel from the A 3 transformation point temperature or higher, is superimposed.
次にこのような効果を含むマルテンサイトまたは焼入れ
組織を焼戻すことによって、表面に脱窒化をともなった
軟質層、その内部に高いピーク硬さを持つ窒化層、さら
にその内部に加工熱処理による強靱化層が形成される。Next, by tempering martensite or a quenched structure containing such effects, a soft layer with denitrification on the surface, a nitride layer with a high peak hardness inside, and toughening by thermomechanical treatment inside A layer is formed.
最後に表面の軟質層にショットピーニング等の噴射加工
を行なうことにより、圧縮残留応力が付与されると同時
に軟質層に歪硬化が起る。Finally, by performing injection processing such as shot peening on the soft layer on the surface, a compressive residual stress is applied and, at the same time, strain hardening occurs in the soft layer.
このような処理によって、表面に圧縮残留応力を含む歪
硬化層、その内側に圧縮残留応力をバックアップする窒
化等による硬化層、さらにその内部に強靱な組織を持つ
強靱化層の３つの特性の異なる複合層が得られる。By such a treatment, three characteristics are different: a strain-hardened layer containing a compressive residual stress on the surface, a hardened layer by nitriding or the like that backs up the compressive residual stress, and a toughened layer having a tough structure inside thereof. A composite layer is obtained.
発明の効果 本発明の方法によれば、鋼の表面には圧縮残留応力を含
む歪硬化層、その内側には窒化による硬化層、そしてそ
の内側にオースフォーム効果を含む強靱化層が連続して
得られる。EFFECTS OF THE INVENTION According to the method of the present invention, a strain-hardened layer containing a compressive residual stress is formed on the surface of steel, a hardened layer by nitriding is formed inside the steel, and a toughening layer containing an ausform effect is continuously formed inside the layer. can get.
しかも、表面の圧縮残留応力を含む層は、硬く、容易に
すべり変形の起らない窒化層にバックアップされ、さら
に内部の強靱化組織を持つ強靱化層にも支持される。こ
のような３層構造から成る表面層は次のような効果を持
つ。Moreover, the layer containing the compressive residual stress on the surface is hard and backed up by the nitride layer that does not easily undergo slip deformation, and is also supported by the toughened layer having the internal toughened structure. The surface layer having such a three-layer structure has the following effects.
（１）表面の圧縮残留応力を持つ層が、その内側の硬い
窒化層にバックアップされているため、過大応力に対し
ても圧縮残留応力の早期消滅が起らない。(1) Since the layer having the compressive residual stress on the surface is backed up by the hard nitride layer inside the layer, the compressive residual stress does not disappear early even if the stress is excessive.
（２）窒化による硬化層が、表面下部に位置するため、
表面の切欠き感受性が低下する。(2) Since the hardened layer by nitriding is located at the lower part of the surface,
Surface notch sensitivity is reduced.
（３）このような傾斜特性を工具類の表面に付与した場
合、隅部や角の部分からのチッピング現象が防止され
る。(3) When such inclination characteristics are imparted to the surface of tools, chipping phenomenon from corners and corners is prevented.
（４）機械要素等で繰返し応力を受ける場合にも、表面
での微小すべり現象が抑制され、表面疲労を防止し、疲
労特性が大幅に改善される。(4) Even when a mechanical element or the like is subjected to repeated stress, a minute slip phenomenon on the surface is suppressed, surface fatigue is prevented, and fatigue characteristics are significantly improved.
（５）ばね等にこのような表面特性を付与した場合、リ
バウンド等により過大応力が作用しても残留応力の脱落
が防止される。(5) When such a surface property is imparted to the spring or the like, the residual stress is prevented from dropping off even if an excessive stress acts due to rebound or the like.
（６）オースフォーム効果を含む内層は、強い異方性と
強靱性を持ち、衝撃応力に対しても優れた抵抗を示す方
位がある。(6) The inner layer including the ausfoam effect has strong anisotropy and toughness, and has an orientation that exhibits excellent resistance to impact stress.
（７）高温で作用する金型、例えばダイカスト用や熱硬
化樹脂成形用の金型に本発明による表面特性を持つ層を
付与した場合、熱応力によるヒートチェックの発生が抑
制される。(7) When a layer having surface characteristics according to the present invention is applied to a mold that operates at high temperature, for example, a mold for die casting or thermosetting resin molding, the occurrence of heat check due to thermal stress is suppressed.
実施例 以下、本発明の実施例を図面に基づいて説明する。Embodiment An embodiment of the present invention will be described below with reference to the drawings.
本発明の実施プロセスは次のとおりである。The implementation process of the present invention is as follows.
（１）鋼の表面に既存の方法で窒化または軟窒化による
表面硬化処理を施す。(1) The surface of steel is subjected to surface hardening treatment by nitriding or soft nitriding by an existing method.
（２）その鋼をA3変態点温度以上に加熱して、その温度
で塑性加工を行ない、直ちに焼入れする。塑性加工にお
ける加工度は所要の大きさとし、きわめてわずかでもよ
い。(2) The steel is heated above the A 3 transformation point temperature, plastically worked at that temperature, and immediately quenched. The degree of working in plastic working is the required size and may be extremely small.
（３）その鋼を焼戻しする。焼戻し条件は、その鋼の使
用目的により変化させる。(3) Temper the steel. The tempering conditions vary depending on the purpose of use of the steel.
（４）焼戻しした鋼の表面にショットピーニングによる
噴射加工を行なう。ショーットピーニングも目的に応じ
て加減する。(4) Injection processing by shot peening is performed on the surface of the tempered steel. Short peening is also adjusted according to the purpose.
第１図，第２図，第３図，第４図はそれぞれプロセス
（１）→（２）→（３）→（４），（１）→（２）→
（３），（１）→（２），（１）を施した後の鋼材断面
の硬さ分布を示した図であり、横軸に表面からの深さ、
縦軸に硬さがとってある。1, 2, 3, and 4 show processes (1) → (2) → (3) → (4), (1) → (2) →
It is the figure which showed hardness distribution of the steel material cross section after giving (3), (1)-> (2), (1), the depth from the surface on the horizontal axis,
The vertical axis is hardness.
本発明の複合表面強化処理方法を用いることにより、第
１図に示すような表面特性を与えた鋼は、従来材（焼入
れ，焼戻し処理）に比較して、疲労限が30〜40％上昇
し、疲労寿命が５〜10倍延長された。By using the composite surface strengthening treatment method of the present invention, the steel having surface characteristics as shown in FIG. 1 has a fatigue limit increased by 30 to 40% as compared with the conventional materials (quenching and tempering treatment). Fatigue life was extended 5 to 10 times.
第１図，第２図，第３図，第４図はそれぞれ異ったプロ
セスを施した後の鋼材断面の硬さ分布を示した図であ
る。FIG. 1, FIG. 2, FIG. 3, and FIG. 4 are diagrams showing hardness distributions of steel cross sections after different processes are performed.
Claims (1)
鋼をA3変態点温度以上に加熱し、その温度で塑性加工を
行ない、直ちに焼入れしてマルテンサイト変態を起さ
せ、焼戻しを施した後、噴射加工を行ない表面の圧縮残
留応力を持つ歪硬化層、その内側の窒化による硬化層、
さらにその内側の加工熱処理による強靱化層の３つの特
性の異なる表面組織構造を付与することを特徴とする複
合表面強化処理方法。1. A steel surface-hardened by nitriding or soft nitriding is heated to a temperature of A 3 transformation point or higher, plastically worked at that temperature, and immediately quenched to cause martensitic transformation and then tempered. , A strain-hardened layer that has a compressive residual stress on the surface after jetting, a hardened layer by nitriding inside,
Further, a composite surface strengthening treatment method characterized by imparting three surface texture structures having different characteristics to the toughened layer by thermomechanical treatment inside thereof.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28190590A JPH079026B2 (en) | 1990-10-22 | 1990-10-22 | Composite surface strengthening treatment method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28190590A JPH079026B2 (en) | 1990-10-22 | 1990-10-22 | Composite surface strengthening treatment method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04157115A JPH04157115A (en) | 1992-05-29 |
| JPH079026B2 true JPH079026B2 (en) | 1995-02-01 |
Family
ID=17645595
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP28190590A Expired - Lifetime JPH079026B2 (en) | 1990-10-22 | 1990-10-22 | Composite surface strengthening treatment method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH079026B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4832790B2 (en) * | 2005-04-19 | 2011-12-07 | Ｄｏｗａサーモテック株式会社 | Steel member surface treatment method and steel member |
-
1990
- 1990-10-22 JP JP28190590A patent/JPH079026B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04157115A (en) | 1992-05-29 |
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