JPH02194120A - Method for directly austempering cast article - Google Patents
Method for directly austempering cast articleInfo
- Publication number
- JPH02194120A JPH02194120A JP26722588A JP26722588A JPH02194120A JP H02194120 A JPH02194120 A JP H02194120A JP 26722588 A JP26722588 A JP 26722588A JP 26722588 A JP26722588 A JP 26722588A JP H02194120 A JPH02194120 A JP H02194120A
- Authority
- JP
- Japan
- Prior art keywords
- cast
- article
- austempering
- temperature
- constant temperature
- 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.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 59
- 238000005279 austempering Methods 0.000 title claims abstract description 22
- 238000005266 casting Methods 0.000 claims abstract description 26
- 238000010438 heat treatment Methods 0.000 claims abstract description 20
- 229910001208 Crucible steel Inorganic materials 0.000 claims abstract description 16
- 230000009466 transformation Effects 0.000 claims abstract description 11
- 229910001018 Cast iron Inorganic materials 0.000 claims abstract description 5
- 238000007711 solidification Methods 0.000 claims abstract description 4
- 230000008023 solidification Effects 0.000 claims abstract description 4
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical class [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 claims description 6
- 150000003839 salts Chemical class 0.000 claims description 6
- 229910002651 NO3 Inorganic materials 0.000 claims description 3
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 3
- 239000003513 alkali Substances 0.000 claims description 3
- IOVCWXUNBOPUCH-UHFFFAOYSA-M Nitrite anion Chemical compound [O-]N=O IOVCWXUNBOPUCH-UHFFFAOYSA-M 0.000 claims description 2
- 238000010791 quenching Methods 0.000 abstract description 4
- 230000000171 quenching effect Effects 0.000 abstract description 4
- 238000002791 soaking Methods 0.000 abstract 1
- 229910052799 carbon Inorganic materials 0.000 description 9
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 8
- 229910001566 austenite Inorganic materials 0.000 description 8
- 229910000831 Steel Inorganic materials 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 239000010959 steel Substances 0.000 description 7
- 238000009826 distribution Methods 0.000 description 6
- 239000010410 layer Substances 0.000 description 6
- 238000012545 processing Methods 0.000 description 5
- 238000009661 fatigue test Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 230000000717 retained effect Effects 0.000 description 4
- 229920002165 CarbonCast Polymers 0.000 description 3
- 229910001563 bainite Inorganic materials 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 229910001141 Ductile iron Inorganic materials 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 238000005242 forging Methods 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 235000010333 potassium nitrate Nutrition 0.000 description 2
- 239000004323 potassium nitrate Substances 0.000 description 2
- 238000003672 processing method Methods 0.000 description 2
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 2
- LPXPTNMVRIOKMN-UHFFFAOYSA-M sodium nitrite Chemical compound [Na+].[O-]N=O LPXPTNMVRIOKMN-UHFFFAOYSA-M 0.000 description 2
- 239000002344 surface layer Substances 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 229910001339 C alloy Inorganic materials 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 229910000760 Hardened steel Inorganic materials 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- 229910000954 Medium-carbon steel Inorganic materials 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000013040 bath agent Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 238000009863 impact test Methods 0.000 description 1
- 238000005495 investment casting Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 239000003507 refrigerant Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 235000010344 sodium nitrate Nutrition 0.000 description 1
- 239000004317 sodium nitrate Substances 0.000 description 1
- 235000010288 sodium nitrite Nutrition 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Landscapes
- Heat Treatment Of Articles (AREA)
Abstract
Description
【発明の詳細な説明】
［産業上の利用分野］
鋳造成形法のなかでも、金型鋳造法、黒鉛型鋳造法、ロ
ストワックス法、■−プロセス、消失模型鋳造法等の鋳
造成形法によれば、容易に高温の鋳物が取出し得るが、
本発明はこれらの精密鋳造品のオーステンパー処理に関
するものである。[Detailed description of the invention] [Industrial application field] Among casting methods, casting methods such as metal mold casting method, graphite mold casting method, lost wax method, ■-process, and disappearing model casting method are used. If high temperature castings can be easily removed,
The present invention relates to austempering treatment of these precision cast products.
［従来の技術Ｊ
球状黒鉛鋳鉄を熱処理によって強靭化する方法としては
、オーステンパー処理がある。[Prior Art J Austempering is a method of toughening spheroidal graphite cast iron by heat treatment.
このオーステンパー処理は、鋳造品をオーステナイト化
温度で加熱保持してから、恒温熱浴中に急冷し、熱浴中
に所定時間保持し恒温変態させ熱浴より取出し室温に冷
却する一連の熱処理工程手順を云う、この恒温変態には
長時間を要することから、処理時間を短縮する方法とし
て、キメナイト法またはジャーフナイト法が採用されて
いる。This austempering process is a series of heat treatment steps in which the cast product is heated and held at the austenitizing temperature, then rapidly cooled in a constant temperature heat bath, and kept in the heat bath for a predetermined period of time to undergo constant temperature transformation, then taken out from the heat bath and cooled to room temperature. Since this isothermal transformation procedure requires a long time, the chimenite method or the jarfnite method is adopted as a method to shorten the processing time.
第１図に、従来の技術による各種のオーステンパー処理
工程図を示す。FIG. 1 shows various austempering process diagrams according to conventional techniques.
図中の符号（Ａ）の工程が標準的な従来法で、次の順序
で行はれる。The step (A) in the figure is a standard conventional method and is performed in the following order.
■鋳造後、■常温迄冷却し、■オーステナイト化温度に
昇温し所定時間保持して、■恒温熱浴中に急冷して所定
時間保持後、■室温迄冷却する。(1) After casting, (2) cool to room temperature, (2) raise the temperature to the austenitizing temperature and hold for a predetermined time, (2) rapidly cool in a constant temperature heat bath and hold for a predetermined time, and (2) cool to room temperature.
Ｉｃ）の工程はキメナイト法で、この処理は工程中（Ａ
）の■の処理後、■恒温熱浴中に急冷し、短時間保持し
て不完全オーステンパー処理する処理法である。The step Ic) is the chimenite method, and this treatment is carried out during the process (A
) After the treatment in (2), the material is rapidly cooled in a constant temperature heat bath and held for a short time to undergo incomplete austempering.
又、（［＋１の工程はジャーフナイト法で、■のオース
テナイト化保持時間及び■恒温熱浴に急冷保持する時間
を短時間とする処理法である。In addition, ([+1 step is the jarfnite method, which is a processing method in which the austenitization retention time (2) and the time for quenching and retention in a constant temperature heat bath (2) are shortened.
［発明が解決しようとする課題］
前述の、従来の標準的なオーステンパー処理法ＴＡＩや
、不完全オーステンパー処理であるキメナイト法［Ｃ）
オーステナイト化と恒温変態時間の両方を短時間で
行うジャーフナイト法（ＤＪなどのいずれの処理法でも
、鋳造品を一旦取出した後、常温からオーステナイト化
温度に昇温保持する方法であり、昇温に要するエネルギ
ー、−旦晶出した炭素をオーステナイトに再固溶させる
ための保持エネルギー、及び高温にて長時間保持するた
めに生じる鋳物表面の脱炭現象対策としての炉気雰囲気
の制御を必要とし、経済面や品質面で改善が必要である
。[Problem to be solved by the invention] The above-mentioned conventional standard austempering method TAI and the chimenite method [C] which is an incomplete austempering treatment
In any treatment method such as the Jerfnite method (DJ), which performs both austenitization and isothermal transformation time in a short time, the casting product is once taken out and then heated and maintained from room temperature to the austenitization temperature. It is necessary to control the energy required for heating, the holding energy to solidify the carbon that has already crystallized into austenite, and the furnace atmosphere as a countermeasure for the decarburization phenomenon on the casting surface that occurs due to long-term holding at high temperatures. Therefore, improvements are needed in terms of economy and quality.
［課題を解決するための手段］
鋳造時の熱エネルギーの活用、鋳型からの取出し温度の
設定、つまり鋳造品が取扱いによって変形することなく
、更には容易に押切り切断が可能になる４０Ｇ’Ｃか６
９００６Ｃの範囲内の温度まで冷却し、続いてオーステ
ナイト化温度に加熱し鋳造品がオーステナイト化温度に
達したならば、それ以上保持することなく恒温熱浴中に
急冷して恒温変態させ靭性のあるベーナイト組織とする
。[Means for solving the problem] Utilizing thermal energy during casting, setting the temperature for taking out from the mold, that is, 40G'C, which allows the cast product to be easily cut by force without being deformed by handling. or 6
The casting is cooled to a temperature within the range of 9006C and then heated to the austenitizing temperature. Once the casting reaches the austenitizing temperature, it is rapidly cooled in a constant temperature heat bath without being held any longer to undergo isothermal transformation and obtain toughness. Become a bainite structure.
本発明のダイレクトオーステンパー処理法を、前述の第
１図を参照して要約すると、
本発明の熱処理法は、図中に（Ｂｌで示す工程であり、
■：ｉ＃造し、■：Ａ、変態点以下の温度に達したとこ
ろで鋳型より取出し、■ニオーステナイト化し、■：恒
温熱浴に急冷、■：室温迄冷却する。To summarize the direct austempering treatment method of the present invention with reference to the above-mentioned FIG.
(2): i# is formed, (2): A, when the temperature reaches the transformation point or below, it is taken out from the mold, (2) it is converted into niostenite, (2) it is rapidly cooled in a constant temperature heat bath, (2) it is cooled to room temperature.
［作用］
鋳造から連続的にオーステナイト化しオーステンパー処
理するため、省エネルギー、短時間処理を可能とし、さ
らに、コスト低減に貢献するところが大変に大きい処理
方法である。[Function] Since it is continuously austenitized and austempered from casting, it is a processing method that saves energy and enables short processing times, and also greatly contributes to cost reduction.
鋳鋼の場合は、消失模型鋳造法を使用すれば鋳型材料の
燃焼により発生するガス中の炭素成分により鋳鋼品の表
面に浸炭層が形成されることにより、上記のダイレクト
オーステンパー処理で表面の浸炭層を硬化させると共に
、鋳鋼品の内部の強度をも上昇させることができる。In the case of cast steel, if the vanishing model casting method is used, a carburized layer will be formed on the surface of the cast steel due to the carbon components in the gas generated by combustion of the mold material, and the surface will be carburized by the above-mentioned direct austempering treatment. In addition to hardening the layer, it is also possible to increase the internal strength of the cast steel product.
［実施例］
１胤■−ユ
本発明のダイレクトオーステンパー処理法により、ダク
タイル鋳鉄を消失模型鋳造法により鋳造し、鋳造に次ぐ
凝固過程で取出し、オーステナイト化温度である８５０
℃に昇温すると同時に４００℃の硝酸カリウム５０％、
亜硝酸ナトリウム５０％の恒温熱浴に急冷し、６０分間
保持して恒温変態させた。この実施例で使用した鋳鉄は
ＦＣＤ ５５に相当し次の化学成分（重量％）を有する
。[Example] 1. According to the direct austempering treatment method of the present invention, ductile cast iron was cast by the investment model casting method, and was taken out in the solidification process following casting, and the iron was taken out at an austenitizing temperature of 850°C.
℃ and at the same time 50% potassium nitrate at 400℃,
It was rapidly cooled in a constant temperature heat bath containing 50% sodium nitrite and kept for 60 minutes to undergo constant temperature transformation. The cast iron used in this example corresponds to FCD 55 and has the following chemical composition (% by weight):
ＣＳｉ Ｍｎ Ｐ Ｓ Ｃｕ
Ｃｒ３．６０ ２．７９ ０．４４ ０．０２ ０．０
１：ｌ Ｇ、２５ ０．０６比較例としては同一鋳造
品を、従来法により常温まで冷却してからオーステナイ
ト化温度９００℃に昇温加熱して６０分ｍ１保持後、４
００℃の恒温熱浴に急冷して６０分間保持させ恒温変態
させたものを供試材とし疲労試験と、衝撃試験及び残留
オーステナイト量を測定した。CSi Mn P S Cu
Cr3.60 2.79 0.44 0.02 0.0
1:l G, 25 0.06 As a comparative example, the same cast product was cooled to room temperature by a conventional method, heated to an austenitizing temperature of 900°C, held for 60 minutes, and then
A fatigue test, an impact test, and the amount of retained austenite were measured using test materials that were rapidly cooled in a constant temperature bath at 00° C. and held for 60 minutes to undergo constant temperature transformation.
第２図に小野式回転曲げ疲労試験結果を示す。Figure 2 shows the results of the Ono rotary bending fatigue test.
表−１には測定数値を示した。疲労試験片は鋳造品をオ
ーステンパー処理してから機械加工により平滑試験片と
して試験に供した。Table 1 shows the measured values. The fatigue test piece was a cast product that was austempered and then machined into a smooth test piece that was subjected to the test.
第２図に示す様に、図中、縦軸に疲労限を横軸に繰返し
数を示す０図中の符号■は、鋳造素材のＳ−Ｎ曲線、■
は従来の熱処理法のＳ−Ｎ曲線、■は本発明の熱処理法
によるＳ−Ｎ曲線で鋳造素材のペースに対し従来の熱処
理法では、疲労限が３７％向上しているのに対し本発明
熱処理力では５３％で疲労限が著し゛く向上している。As shown in Figure 2, the symbol ■ in Figure 0 shows the fatigue limit on the vertical axis and the number of repetitions on the horizontal axis is the S-N curve of the cast material, ■
is the S-N curve of the conventional heat treatment method, and ■ is the S-N curve of the heat treatment method of the present invention. Compared to the pace of cast materials, the conventional heat treatment method improved the fatigue limit by 37%, whereas the present invention improved the fatigue limit by 37%. In terms of heat treatment strength, the fatigue limit is significantly improved at 53%.
第３図は、衝撃値と残留オーステナイト量を示すもので
２本発明の熱処理法による４００℃恒温熱浴での保持時
間による変化を観察した。FIG. 3 shows the impact value and the amount of retained austenite, and observed the changes depending on the holding time in a 400° C. constant temperature heat bath by the heat treatment method of the present invention.
６０分処理で衝撃値が高く、シかも残留オーステナイト
量も高い、残留オーステナイト量は恒温保持時間が６０
分処理を境として、急激に低下する傾向を示す。The impact value is high after 60 minutes of treatment, and the amount of residual austenite is also high after 60 minutes of constant temperature holding time.
It shows a tendency to rapidly decrease after the separation process.
本発明の熱処理法であるダイレクトオーステンパー処理
法が疲労限、衝撃値、残留オーステナイト量、共に６０
分処理で高い結果が得られた。The direct austempering method, which is the heat treatment method of the present invention, has a fatigue limit, impact value, and retained austenite amount of 60%.
High results were obtained with separate processing.
この理由については、鋳造温度１４５０℃の高温から鋳
造し、−次黒鉛化が完了して、球状黒鉛以外のマトリッ
クス（基質）中の炭素濃度か高いためＳ曲線のノーズ（
鼻）が右にずれベーナイトフェライトと高炭素で安定性
のあるオーステナイト組織になるためと考λられる。The reason for this is that the nose of the S curve (
It is thought that this is because the nose) shifts to the right and becomes a stable austenite structure with bainite ferrite and high carbon.
宜ｌ■Ｌニヱ・
本発明の熱処理法をｉＪ）鋼に適用したもので試料全体
としての化学成分（重量％）を下記に示す。The heat treatment method of the present invention was applied to iJ) steel, and the chemical composition (% by weight) of the sample as a whole is shown below.
ＣＳｉ Ｍｎ Ｐ Ｓ
Ｏ，２５０，２２０，４２０，０２０，０２この実施例
では恒温温浴により硝酸ナトリウムの単位を使用した。CSi Mn P SO, 250, 220, 420, 020, 02 This example used a unit of sodium nitrate with a constant temperature bath.
消失横型！＃造法により鋳造する際には、鋳型が高温で
消失する際の炭化水素系発生ガスと接触するため鋳鋼表
面が浸炭する。低次：ｌ：！Ｊ鋼の場合、このダイレク
トオーステンパー処理法により、表面浸炭層部分なベー
ナイト化するか又はダイレクトマルテンパー処理によっ
て。Disappearing horizontal type! #When casting using the casting method, the surface of the cast steel becomes carburized because it comes into contact with the hydrocarbon-based gas generated when the mold disappears at high temperatures. Lower order:l:! In the case of J steel, the surface carburized layer is turned into bainitic by this direct austempering method, or by direct martempering.
表面浸炭層部をマルテンサイト化し硬化させ、基質の非
浸炭部は素材である低炭素鋼程度の硬化にとどめ靭性に
富む組織とすることが短時間で低価格で可能になる。The surface carburized layer is martensited and hardened, and the non-carburized part of the matrix is hardened to the same level as the low carbon steel material, making it possible to create a structure with high toughness in a short time and at a low cost.
又、当然のことながら、中炭素鋼、中炭素合金鋼、高合
金鋼などは、ｉｓｔｇ品とすることにより本発明の熱処
理法で、オーステンパー処理が可能である。但し、この
場合、鍛鋼品については、鍛造焼入と云う方法が公知で
あるが、鋳鋼品は鋼の鍛造品と違い鋳造組織からの恒温
変態であり、ＩＮ造焼入とは異なるものである。Further, as a matter of course, medium carbon steel, medium carbon alloy steel, high alloy steel, etc. can be austempered by the heat treatment method of the present invention by using them as ISTG products. However, in this case, for forged steel products, a method called forging quenching is publicly known, but unlike forged steel products, cast steel products undergo isothermal transformation from a cast structure, which is different from IN forging and quenching. .
消失模型鋳造法で低炭素鋳鋼を鋳造し１本発明の熱処理
法によるダイレクトオーステンパー処理により、表面浸
炭部分のベーナイト化、又はマルテンサイトとするもの
である。Low-carbon cast steel is cast by the disappearance model casting method, and the surface carburized portion is converted to bainite or martensite by direct austempering treatment by the heat treatment method of the present invention.
この実施例では低炭素鋳鋼５２ＳＧ相当の組成を有する
鋳鋼を消失模型鋳造法で成形鋳造し、ダイレクトマルテ
ンパー処理した。第４図にマルテンパーした組織と硬度
分布を示す。In this example, a cast steel having a composition equivalent to low carbon cast steel 52SG was cast by an investment casting method and subjected to direct martempering treatment. Figure 4 shows the martempered structure and hardness distribution.
浸炭している表面層は、十分硬化していることが、第５
図の硬度分布測定結果から判る。硬化部にセメンタイト
状のものが観察されるため、 ｘｌＩＩｉＩ口折により
炭化物の同定を行った、第６図と第７図はＸ線回折によ
る炭化物の同定結果を示すものであるが、これらのＸ線
回折では炭化物は確認できながかった。The fifth point is that the carburized surface layer is sufficiently hardened.
This can be seen from the hardness distribution measurement results shown in the figure. Since a cementite-like substance was observed in the hardened part, the carbide was identified by XlIIIiI splitting. Figures 6 and 7 show the identification results of the carbide by X-ray diffraction. No carbides could be confirmed by line diffraction.
そこで、消失模型鋳造法によって得られたｉ＃鋼表面浸
炭層の炭素濃度分布をＸ線マイクロアナライザーにより
測定した結果を第８図に示した。Therefore, the carbon concentration distribution of the i# steel surface carburized layer obtained by the vanishing model casting method was measured using an X-ray microanalyzer, and the results are shown in FIG.
図から判る様に最表面の炭素濃度はＣ＝ １．５％にも
及び、Ｃ＝０．６％となる迄の表面からの距離は約１．
ｈ／ｍであることが、Ｘ線マイクロアナライザーにより
確認できた。As can be seen from the figure, the carbon concentration at the outermost surface reaches C=1.5%, and the distance from the surface until C=0.6% is about 1.5%.
h/m was confirmed by an X-ray microanalyzer.
このように、浸炭焼入鋼の組成を持った表面層を有する
ＩＪ＃鋼を消失模型鋳造法により鋳造してから、ダイレ
クトマルテンパー処理することにより強靭で耐摩耗性の
あるｉ＊ｍ硬化品を経済的に安価に製作し得ることが確
認できた。In this way, IJ# steel, which has a surface layer with the composition of carburized and hardened steel, is cast using the investment model casting method, and then subjected to direct martempering treatment to produce tough and wear-resistant i*m hardened products. It was confirmed that it could be manufactured economically and at low cost.
【発明の効果］
本発明の熱処理法であるダイレクトオーステンパー処理
法は、Ｕ造品を常温迄冷却することなくオーステンパー
処理するため、省エネルギー化は勿論、処理時間の短縮
化が計られる。[Effects of the Invention] The direct austempering method, which is the heat treatment method of the present invention, austempers the U-shaped product without cooling it to room temperature, which not only saves energy but also shortens the processing time.
低炭素鋳鋼で消失模型鋳造法と併用することにより表面
に浸炭層を形成させ表面硬化を行なうことも出来る。It is also possible to harden the surface by forming a carburized layer on the surface of low carbon cast steel by using it in conjunction with the disappearing model casting method.
又１本発明法に用いる冷媒としての恒温塩浴剤は、処理
温度が２５０℃〜４５０℃の範囲と高いため良品質を確
保する点から、硝石系塩の単塩として硝酸カリ、又は硝
酸ソーグーなと、または混合塩としては硝酸アルカリ（
４０〜６０％）と亜硝酸アルカリ（６０〜４０％）が好
適である。In addition, since the constant temperature salt bath agent used as the refrigerant used in the method of the present invention has a high processing temperature in the range of 250°C to 450°C, in order to ensure good quality, potassium nitrate or sour nitrate is used as a single saltpeter salt. Nato, or as a mixed salt, alkaline nitrate (
40-60%) and alkali nitrite (60-40%) are preferred.
その理由は、低融点で塩浴からの塩の持出し量が少いこ
と、冷却能が大きいこと、作業性が良いこと１組成変化
部ち劣化が少く、安定していることにある。オーステン
パー処理に際し歪を軽減するには均一冷却が必須条件で
あり、本発明で選定した塩浴は特徴の一つを成すもので
ある。The reasons for this are that it has a low melting point and a small amount of salt taken out from the salt bath, has a large cooling capacity, is easy to work with, and is stable with less deterioration due to compositional changes. Uniform cooling is an essential condition for reducing distortion during austempering treatment, and the salt bath selected in the present invention is one of its characteristics.
本発明法のダイレクトオーステンパー処理によれば、疲
労強度が従来法のオーステンパー処理に比し、オーステ
ナイト化温度が低く短時間処理であるにもかかわらず、
１０％以上と高い疲労強度が得られるが、これはオース
テナイト化に於けるオーステナイト中への炭素固溶量が
高いことによるものと考えられる。According to the direct austempering process of the present invention, the fatigue strength is lower than that of the conventional austempering process, despite the fact that the austenitizing temperature is low and the process is short.
A high fatigue strength of 10% or more is obtained, which is thought to be due to the high amount of solid solution of carbon in austenite during austenitization.
第１図は、本発明と従来の熱処理工程を示すグラフ、第
２図は、鋳鉄、鋳放し材、本発明と従来の熱処理工程を
施した試料に対する回転曲げ疲労試験結果を示すグラフ
、第３図は１本発明の熱処理工程での恒温保持時間の変
化に伴う衝撃値と残留オーステナイト量の変化を示すグ
ラフ、第４図は本発明の熱処理を施した鋳鋼品の表面付
近の顕微鏡写真、第５図は本発明の熱処理を施した鋳鋼
品の表面付近の硬度分布グラフ、第６図は本発明の熱処
理を施した鋳鋼品の表面付近のｘ！１回折のチャート、
第７図は本発明の熱処理を施した鋳鋼品の表面付近のＸ
線回折による炭化物同定図形、第８図は本発明の熱処理
を施した鋳鋼品の表面付近のＸ線マイクロアナライザー
による炭素濃度分布を示すグラフである。Fig. 1 is a graph showing the heat treatment process of the present invention and the conventional heat treatment process; Fig. 2 is a graph showing the results of rotary bending fatigue tests for cast iron, as-cast materials, and samples subjected to the heat treatment process of the present invention and the conventional process; Figure 1 is a graph showing changes in impact value and amount of retained austenite with changes in constant temperature holding time in the heat treatment process of the present invention; Figure 5 is a hardness distribution graph near the surface of a cast steel product that has been heat treated according to the present invention, and Figure 6 is a hardness distribution graph near the surface of a cast steel product that has been heat treated according to the present invention. 1st diffraction chart,
Figure 7 shows the X near the surface of the cast steel product that has been heat treated according to the present invention.
Carbide identification pattern by line diffraction. FIG. 8 is a graph showing the carbon concentration distribution near the surface of a cast steel product subjected to the heat treatment of the present invention, measured by an X-ray microanalyzer.
Claims (1)
度が４００〜９００℃まで低下した時点で鋳型から取り
出し：予め準備してあるオーステナイト化用高温炉内で
均熱後直ちに恒温熱浴中に急冷し所定時間保持して恒温
変態を進行させて： 高強度、高靭性を得ることを特徴とする鋳鉄のダイレク
トオーステンパー処理法。 ２、鋳鋼を消失模型鋳造法によって鋳造し鋳造品の表面
に浸炭層を形成させ；それに次ぐ凝固の過程で鋳造品の
温度が４００〜９００℃まで低下した時点で鋳型から取
り出し；予め準備してあるオーステナイト化用高温炉内
で均熱後直ちに恒温熱浴中に急冷し所定時間保持して恒
温変態を進行させるとともに前記表面の浸炭層を硬化さ
せて； 高強度、高靭性を得ることを特徴とする鋳鋼のダイレク
トオーステンパー処理法。 ３、前記の恒温熱浴に使用する溶融塩は、硝酸アルカリ
と亜硝酸アルカリの少なくとも１種を含む硝石系塩であ
る請求項１および２に記載のダイレクトオーステンパー
処理法。[Claims] 1. Cast iron: Then, when the temperature of the cast product drops to 400 to 900°C in the solidification process, it is removed from the mold: Equalized in a high-temperature austenitizing furnace prepared in advance. A direct austempering treatment method for cast iron that is characterized by obtaining high strength and high toughness: immediately after heating, it is rapidly cooled in a constant temperature heat bath and held for a predetermined time to proceed with constant temperature transformation. 2. Cast the cast steel using the investment model casting method to form a carburized layer on the surface of the cast product; take it out from the mold when the temperature of the cast product drops to 400-900°C during the subsequent solidification process; prepare in advance. Immediately after being soaked in a high-temperature furnace for austenitization, it is rapidly cooled in a constant temperature bath and held for a predetermined period of time to advance isothermal transformation and harden the carburized layer on the surface; it is characterized by obtaining high strength and high toughness. Direct austempering treatment method for cast steel. 3. The direct austempering method according to claims 1 and 2, wherein the molten salt used in the constant temperature bath is a saltpetre salt containing at least one of alkali nitrate and alkali nitrite.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26722588A JPH02194120A (en) | 1988-10-25 | 1988-10-25 | Method for directly austempering cast article |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26722588A JPH02194120A (en) | 1988-10-25 | 1988-10-25 | Method for directly austempering cast article |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02194120A true JPH02194120A (en) | 1990-07-31 |
Family
ID=17441877
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP26722588A Pending JPH02194120A (en) | 1988-10-25 | 1988-10-25 | Method for directly austempering cast article |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02194120A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012002286A (en) * | 2010-06-17 | 2012-01-05 | Nippon Pop Rivets & Fasteners Ltd | Blind fastener and method for manufacturing same |
| CN110938731A (en) * | 2019-12-24 | 2020-03-31 | 陕西宏远航空锻造有限责任公司 | Method for improving rust resistance of investment casting austenitic stainless steel |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6024318A (en) * | 1983-02-25 | 1985-02-07 | Hitachi Metals Ltd | Manufacture of spheroidal graphite cast iron |
| JPS60221525A (en) * | 1984-04-18 | 1985-11-06 | Kubota Ltd | Manufacture of ductile cast iron pipe with high strength |
| JPS61133361A (en) * | 1984-11-30 | 1986-06-20 | Ngk Insulators Ltd | Spheroidal graphite cast iron and its manufacture |
| JPS61288011A (en) * | 1985-06-13 | 1986-12-18 | Kubota Ltd | Production of high strength casting spheroidal graphite cast iron |
-
1988
- 1988-10-25 JP JP26722588A patent/JPH02194120A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6024318A (en) * | 1983-02-25 | 1985-02-07 | Hitachi Metals Ltd | Manufacture of spheroidal graphite cast iron |
| JPS60221525A (en) * | 1984-04-18 | 1985-11-06 | Kubota Ltd | Manufacture of ductile cast iron pipe with high strength |
| JPS61133361A (en) * | 1984-11-30 | 1986-06-20 | Ngk Insulators Ltd | Spheroidal graphite cast iron and its manufacture |
| JPS61288011A (en) * | 1985-06-13 | 1986-12-18 | Kubota Ltd | Production of high strength casting spheroidal graphite cast iron |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012002286A (en) * | 2010-06-17 | 2012-01-05 | Nippon Pop Rivets & Fasteners Ltd | Blind fastener and method for manufacturing same |
| CN110938731A (en) * | 2019-12-24 | 2020-03-31 | 陕西宏远航空锻造有限责任公司 | Method for improving rust resistance of investment casting austenitic stainless steel |
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