JP6716156B2 - Resource-saving cold press die steel with excellent surface treatment - Google Patents
Resource-saving cold press die steel with excellent surface treatment Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims description 105
- 239000010959 steel Substances 0.000 title claims description 105
- 238000004381 surface treatment Methods 0.000 title description 11
- 150000001247 metal acetylides Chemical class 0.000 claims description 36
- 238000012360 testing method Methods 0.000 claims description 31
- 229910052804 chromium Inorganic materials 0.000 claims description 19
- 229910052750 molybdenum Inorganic materials 0.000 claims description 11
- 239000011248 coating agent Substances 0.000 claims description 9
- 238000000576 coating method Methods 0.000 claims description 9
- 229910052748 manganese Inorganic materials 0.000 claims description 9
- 229910052799 carbon Inorganic materials 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 2
- 229910052751 metal Inorganic materials 0.000 claims description 2
- 239000002184 metal Substances 0.000 claims description 2
- 238000011282 treatment Methods 0.000 description 33
- 239000000463 material Substances 0.000 description 31
- 230000000052 comparative effect Effects 0.000 description 28
- 239000000203 mixture Substances 0.000 description 24
- 238000005496 tempering Methods 0.000 description 22
- 238000005240 physical vapour deposition Methods 0.000 description 17
- 238000010791 quenching Methods 0.000 description 15
- 230000000171 quenching effect Effects 0.000 description 15
- 229910045601 alloy Inorganic materials 0.000 description 14
- 239000000956 alloy Substances 0.000 description 14
- 239000000126 substance Substances 0.000 description 8
- 238000011156 evaluation Methods 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 238000005336 cracking Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000005204 segregation Methods 0.000 description 4
- 229910001315 Tool steel Inorganic materials 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000005242 forging Methods 0.000 description 3
- 230000014509 gene expression Effects 0.000 description 3
- 238000009863 impact test Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 238000009628 steelmaking Methods 0.000 description 3
- 238000005482 strain hardening Methods 0.000 description 3
- 238000005520 cutting process Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000013011 mating Effects 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
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- 238000011161 development Methods 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000005461 lubrication Methods 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
- 239000011733 molybdenum Substances 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
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Description
この発明は表面処理性に優れた省資源の冷間プレス金型用鋼に関し、特に表面処理に関する化学成分の最適化と、新たな条件式を規定し、鋼中の粗大な一次炭化物の個数を規定し、かつ粗大な一次炭化物の面積率を制限した冷間プレス金型用鋼と、さらに、この一次炭化物の条件を満たす冷間プレス金型用鋼に、ＴＤ処理およびＰＶＤ処理を施して被膜を生成した冷間プレス金型用鋼に関する。 The present invention relates to a resource-saving cold press die steel excellent in surface treatment property, particularly optimization of chemical components relating to surface treatment and a new conditional expression to determine the number of coarse primary carbides in the steel. A cold-press die steel that regulates the area ratio of coarse primary carbides, and a cold-press die steel that satisfies the conditions of this primary carbide is subjected to TD treatment and PVD treatment to form a film. Of the cold-press die steel produced.
近年、自動車産業におけるハイテン適用の拡大に代表される被加工材の高強度化および冷間塑性加工技術の進歩によるネットシェイプ化や工程集約の流れを受け、冷間加工金型への負荷がいっそうに高まっている。このような高負荷環境では、冷間プレスなどの成型用金型や工具と被加工材の潤滑不足による焼きつきが問題となり、各種表面処理による改善がなされてきた。 In recent years, the load on cold-working dies has been further increased due to the trend toward higher net strength and cold-working technology, which is represented by the expansion of high-tensile applications in the automobile industry, and the progress of cold plastic processing technology, which has resulted in net shaping and process consolidation. Is increasing. In such a high load environment, seizure due to insufficient lubrication between a molding die such as a cold press and a tool and a work material becomes a problem, and various surface treatments have been improved.
従来、冷間プレスなどの成型用金型には、ＪＩＳに記載されたＳＫＤ１１あるいはＡＩＳＩで規格化されているＤ２などの冷間金型用工具鋼が多用されている。これらの冷間金型用工具鋼は、鋼中に１．５％前後のＣと１２％前後のＣｒを添加することにより、粗大なＭ7Ｃ3一次炭化物を形成し、優れた耐摩耗性を発揮する鋼材となっている。一方、これらの鋼材は一次炭化物を多量に含むことが原因で、靭性及び加工性が悪い。 Conventionally, tool steels for cold molds such as SKD11 described in JIS or D2 standardized by AISI are often used for molding dies such as cold presses. These cold die tool steels form coarse M 7 C 3 primary carbides by adding C of about 1.5% and Cr of about 12% to the steel, and have excellent wear resistance. It is a steel material that demonstrates. On the other hand, these steel materials are poor in toughness and workability because they contain a large amount of primary carbides.
このような背景の下で、鋼成分の調整によって一次炭化物の大きさや面積率を最適化し、高面圧をなるべく均一に分散させ、マトリックスの局所的な塑性変形を緩和することで、被膜のクラック発生を抑制した冷間工具が知られている（例えば、特許文献１参照。）。しかし、このものは、本願発明が開発しようとする冷間金型用鋼と成分系が異なり、また、特許文献１はダイヤモンドライクカーボン膜のみに関するものである。 Against this background, the size and area ratio of the primary carbides are optimized by adjusting the steel composition, the high surface pressure is dispersed as evenly as possible, and the local plastic deformation of the matrix is relaxed, thereby cracking the coating film. A cold tool whose generation is suppressed is known (see, for example, Patent Document 1). However, this is different from the cold die steel which the present invention intends to develop in composition, and Patent Document 1 relates only to a diamond-like carbon film.
他方、冷間プレス金型として必要な最小限の硬度、靱性、耐摩耗性などの特性を確保した上で、金型材料の費用を増大させる高価な元素の使用を極力削減することで、安価な冷間プレス金型用鋼が提案（例えば、特許文献２参照。）されている。しかし、このものは、省資源の冷間工具鋼に関するが、本願に比してＭｎの成分範囲が低く、Ｃｒの成分範囲が高いなど、本願発明が開発しようとする鋼成分の範囲と相違し、さらに表面処理性に関する記載が示されていない。 On the other hand, while ensuring the minimum hardness, toughness, wear resistance, and other properties required for cold-pressing dies, the use of expensive elements that increase the cost of die materials is reduced as much as possible to reduce costs. Another cold press die steel has been proposed (for example, refer to Patent Document 2). However, this relates to a resource-saving cold tool steel, but differs from the range of the steel composition to be developed by the present invention in that the composition range of Mn is lower and the composition range of Cr is higher than that of the present application. Further, there is no description regarding surface treatability.
一般に、工業製品は、製品デザインの短期化および多様化が求められることから、現在のニーズとして、少量多品種生産品が求められている。各種製造業はその傾向に追従する結果、製造コストの低減目的として、金属製品の加工分野では、従来は長寿命が得られる金型材料が求められてきたが、近年では必要最低限の特性を有した低価格な金型材料の要望が拡大している。そこで、冷間プレス用の金型材料である冷間工具鋼においては、前記要望に応えるために、金型製造費用と工期の削減を目的として、被削性の改善や焼入焼戻し後の変形の低減や寸法変化の低減を狙った開発も進められてきた。しかし、それらの多くは、冷間プレス用途としての特性、特に耐摩耗性や、耐焼付き性を維持および向上させるために、高価な希少元素を多く含有している場合が多く、結果として十分な金型費用の削減に貢献できるものになっていない。 In general, industrial products are required to be short-term and diversified in product design, and therefore, as current needs, small-quantity multi-product production products are required. As a result of various manufacturing industries following this trend, in the field of metal product processing, mold materials that have long life have been conventionally required for the purpose of reducing manufacturing costs, but in recent years, the minimum required characteristics have been required. The demand for low-priced mold materials has been expanding. Therefore, in cold tool steel, which is a die material for cold press, in order to meet the above-mentioned demand, in order to reduce die manufacturing cost and construction period, machinability is improved and deformation after quenching and tempering is performed. The development has also been promoted aiming at reduction of dimensional change and dimensional change. However, many of them often contain a large amount of expensive rare elements in order to maintain and improve the properties as cold press applications, particularly wear resistance and seizure resistance, and as a result, sufficient It cannot contribute to the reduction of mold cost.
本出願の発明が解決しようとする課題は、省資源型の冷間工具鋼に関するが、省資源型の冷間プレス金型用鋼の特許文献２と異なり、表面処理性に関する成分の添加量の最適化と、さらに新たな成分の添加と条件式および粗大な一次炭化物の数や粗大な一次炭化物の面積率などを追加した冷間プレス金型用鋼とし、さらに、この一次炭化物の条件を満たす冷間プレス金型用鋼に、ＴＤ処理あるいはＰＶＤ処理を施して被膜を生成した冷間プレス金型用鋼を提供することである。 The problem to be solved by the invention of the present application relates to a resource-saving cold tool steel, but unlike Patent Document 2 of a resource-saving cold press die steel, the addition amount of components relating to surface treatability is Optimization, addition of new components and conditional expressions, and addition of the number of coarse primary carbides, area ratio of coarse primary carbides, etc. to a cold press die steel, and further satisfy the conditions of this primary carbide It is an object of the present invention to provide a cold press die steel, which is produced by subjecting a cold press die steel to TD treatment or PVD treatment to form a film.
上記の課題を解決するための手段は、第１の手段では、化学成分が、質量％で、Ｃ：０．７５〜０．９０％、Ｓｉ：０．３０〜０．９０％、Ｍｎ：０．３５〜１．００％、Ｃｒ：５．７０〜８．２０％、Ｍｏ：０．２０〜０．５０％、Ａｌ：０．０１〜０．１５％を含有し、残部がＦｅおよび不可避不純物からなり、式（１）におけるＲ値が、１．５０≦Ｒ値≦１．８０で、式（２）におけるＨ値が、Ｈ値≦１０．０で、９００μｍ2以上の面積を有する粗大な一次炭化物の数が１ｍｍ2当り４．９個以下、粗大な一次炭化物の面積率が８％以下であることを特徴とする冷間プレス金型用鋼である。
ただし、上記の［％元素］は元素量であり、質量％を示し、Ｒ値およびＨ値は以下に示すとおりである。
Ｒ値＝０．９８３×［％Ｃ］／Ｃｅｑ、
ただし、Ｃｅｑ＝０．０６３×［％Ｃｒ］＋０．０９３×［％Ｍｏ］・・・式（１）
Ｈ値＝［％Ｃｒ］／（１．８４×［％Ｍｎ］＋３．４４×［％Ａｌ］・・・式（２）
Means for solving the above-mentioned problems is, in the first means, a chemical component in mass%, C: 0.75 to 0.90%, Si: 0.30 to 0.90%, Mn: 0. .35 to 1.00%, Cr: 5.70 to 8.20%, Mo: 0.20 to 0.50%, Al: 0.01 to 0.15%, with the balance being Fe and inevitable impurities. And the R value in the formula (1) is 1.50≦R value≦1.80, the H value in the formula (2) is H value≦10.0, and the coarse value has an area of 900 μm 2 or more. The steel for cold press die is characterized in that the number of primary carbides is 4.9 or less per 1 mm 2 and the area ratio of coarse primary carbides is 8% or less.
However, the above [% element] is an element amount and indicates mass %, and the R value and the H value are as shown below.
R value = 0.983 x [%C]/Ceq,
However, Ceq=0.063×[%Cr]+0.093×[%Mo] Equation (1)
H value=[%Cr]/(1.84×[%Mn]+3.44×[%Al]...Equation (2)
第２の手段では、
質量％で、Ｓ＝０．１２０％以下を含有したことを特徴とする第１の手段における冷間プレス金型鋼。
In the second way,
The cold press die steel according to the first means, characterized in that it contains S=0.120% or less in mass %.
第３の手段では、第１の手段または第２の手段における冷間プレス金型用鋼の表面に、スクラッチ試験による臨界荷重がある一定値以上となることを特徴とする皮膜を有する冷間プレス金型用鋼である。 According to a third means, a cold press having a film, characterized in that a critical load by a scratch test is a certain value or more on a surface of the steel for cold press die according to the first means or the second means. It is steel for molds.
本発明は、第１の手段では、ＣｒとＭｎの添加量に対するＣの添加量のバランスに配慮することで、高価なＣｒの添加量を最小限に抑え、同様に高価な元素であるＶについては積極的な添加を必要とすることなく、冷間プレス金型などの冷間成形用工具として必要な特性を有する冷間金型用鋼を、比較的に低価格で製造できる。 According to the first aspect of the present invention, the amount of expensive Cr added is minimized by considering the balance of the amount of added C with respect to the amount of added Cr and Mn. Can manufacture cold-die steel having the properties required for cold-forming tools such as cold-press dies at a relatively low cost without the need for aggressive addition.
第２の手段では、第１の手段の冷間金型用鋼の化学成分に、Ｓを０．１２０％以下を含有するときは、製鋼過程で形成したＭｎＳが鋼材の被削性を高め切削費用の削減に寄与する。 In the second means, when the chemical composition of the cold die steel of the first means contains 0.120% or less of S, MnS formed in the steelmaking process enhances the machinability of the steel material and cuts it. Contributes to cost reduction.
第３の手段では、第１の手段または第２の手段の冷間プレス金型用鋼にＴＤ処理によるあるいはＰＶＤ処理による皮膜をさらに形成しているので、表面処理すなわち臨界荷重に優れた冷間金型用鋼材となっている。ＴＤ処理とは、８５０〜１０５０℃程度の溶融した塩浴中に被処理材を浸漬することにより、被処理材の表面に炭化物や硼化物、もしくはその他の化合物層を形成させる皮膜処理である。ＰＶＤ処理とは、スパッタや蒸着によって被処理材の表面に窒化物やＤＬＣなどの相を形成させる皮膜処理である。 In the third means, a film is further formed on the cold press die steel of the first means or the second means by the TD treatment or the PVD treatment, so that the surface treatment, that is, the cold working excellent in critical load is performed. It is a steel material for molds. The TD treatment is a film treatment in which a material to be treated is immersed in a molten salt bath at about 850 to 1050° C. to form a carbide, boride, or other compound layer on the surface of the material to be treated. The PVD treatment is a film treatment for forming a phase such as nitride or DLC on the surface of a material to be treated by sputtering or vapor deposition.
発明を実施するための形態の記載に先立ち、課題を解決するための手段における本願発明の第１の手段の冷間プレス金型用鋼の化学成分、化学成分中の［％Ｃｒ］と［％Ｍｎ］および［％Ａｌ］の特定比の値、粗大な一次炭化物の数および粗大な一次炭化物の面積率の規定、さらに第２の手段の冷間プレス金型用鋼の、上記第１の手段の一次炭化物の条件を満たす金型用鋼に生成するＴＤ処理あるいはＰＶＤ処理による被膜を生成した冷間プレス金型用鋼の限定理由について順次説明する。ただし、化学成分は質量％で示し、さらに、［％元素］は合金元素量であり質量％の数値を示す。 Prior to the description of the modes for carrying out the invention, the chemical composition of the steel for cold press die of the first means of the present invention in the means for solving the problems, [% Cr] in the chemical composition and [%] Mn] and [% Al] specific ratio values, definition of the number of coarse primary carbides and area ratio of coarse primary carbides, and the first means of the cold pressing die steel of the second means. The reasons for limiting the cold-press die steel having a coating formed by the TD treatment or the PVD treatment, which is produced on the die steel satisfying the condition of primary carbide, will be sequentially described. However, the chemical composition is shown by mass %, and the [% element] is the amount of alloying element and shows the numerical value of mass %.
Ｃ：０．７５〜０．９０％
Ｃは、十分な焼入性を確保し、炭化物を形成させることで、硬さや耐摩耗性を得るための元素である。Ｃが０．７５％未満であると十分な硬さや耐摩耗性が得られない。Ｃが０．９０％より多いと、炭化物の粗大化および凝固偏析を助長し、靱性を阻害する。そこで、Ｃは０．７５〜０．９０％とする。望ましくは、Ｃ：０．７５〜０．８５％である。
C: 0.75 to 0.90%
C is an element for securing hardness and wear resistance by ensuring sufficient hardenability and forming a carbide. If C is less than 0.75%, sufficient hardness and wear resistance cannot be obtained. When C is more than 0.90%, it promotes coarsening and solidification segregation of carbides and impairs toughness. Therefore, C is 0.75 to 0.90%. Desirably, C: 0.75 to 0.85%.
Ｓｉ：０．３０〜０．９０％
Ｓｉは、製鋼での脱酸効果および鋼の焼入性を確保するための元素である。Ｓｉが０．３０％未満では、これらの効果が得られない。Ｓｉが０．９０％より多すぎると、靱性が低下する。そこで、Ｓｉは０．３０〜０．９０％とする。
Si: 0.30 to 0.90%
Si is an element for ensuring the deoxidizing effect in steelmaking and the hardenability of steel. If Si is less than 0.30%, these effects cannot be obtained. If Si is more than 0.90%, the toughness decreases. Therefore, Si is set to 0.30 to 0.90%.
Ｍｎ：０．３５〜１．００％
Ｍｎは、Ｓｉ同様に脱酸材として添加をし、焼入性の確保にも寄与する元素である。Ｍｎが０．３５％未満では、硬さと焼入性が確保できず、Ｍｎが１．００％よリ多いと靱性が低下する。そこで、Ｍｎは０．３５〜１．００％とする。
Mn: 0.35-1.00%
Mn is an element that is added as a deoxidizing material like Si and contributes to ensuring hardenability. If Mn is less than 0.35%, hardness and hardenability cannot be secured, and if Mn is more than 1.00%, toughness decreases. Therefore, Mn is set to 0.35 to 1.00%.
Ｃｒ：５．７０〜８．２０％
Ｃｒは、焼入性を改善する元素で、炭化物を形成して耐摩耗性に寄与する元素である。Ｃｒが５．７０％未満では、十分な炭化物を形成して耐摩耗性に寄与することができない。一方、Ｃｒが８．２０％より多すぎると、偏析を助長し、靱性および熱処理後の寸法変化が大きくなる。
Cr: 5.70-8.20%
Cr is an element that improves hardenability and is an element that forms carbides and contributes to wear resistance. If Cr is less than 5.70%, sufficient carbides cannot be formed to contribute to wear resistance. On the other hand, if the Cr content is more than 8.20%, segregation is promoted, and toughness and dimensional change after heat treatment increase.
Ｍｏ：０．２０〜０．５０％
Ｍｏは、焼入性と二次硬化や耐摩耗性に寄与する元素である。Ｍｏが０．２０％より少ないと、焼入性と二次硬化や耐摩耗の効果が得られない。Ｍｏを０．５０％より過剰に添加しても、効果が飽和するばかりか、偏析を助長し、炭化物が粗大凝集することによって靭性を低下させる。さらにＭｏは高価な元素でありコストが嵩む。そこで、Ｍｏは０．２０〜０．５０％とする。
Mo: 0.20 to 0.50%
Mo is an element that contributes to hardenability, secondary hardening, and wear resistance. If the Mo content is less than 0.20%, the effects of hardenability, secondary hardening and wear resistance cannot be obtained. Even if Mo is added in excess of 0.50%, not only the effect is saturated, but also segregation is promoted and coarse toughening of the carbide reduces the toughness. Further, Mo is an expensive element and the cost increases. Therefore, Mo is set to 0.20 to 0.50%.
Ｓ：０．１２０％以下
Ｓは、鋼材の被削性を改善する元素である。Ｓは製鋼の過程でＭｎと結合してＭｎＳを形成する。このＭｎＳが切削加工の際に破壊の起点になることで、鋼材の被削性を高め、切削加工費用の削減に寄与する。ただし、同時に、鋼材の靭性を低下させる要因にもなることから、過剰な添加は金型としての機能を大幅に損なうことになるので、上限を０．１２０％とすることで添加しても良い。
S: 0.120% or less S is an element that improves the machinability of steel materials. S combines with Mn in the process of steel making to form MnS. This MnS serves as a starting point of fracture during cutting, which enhances machinability of the steel material and contributes to reduction of cutting cost. However, at the same time, it also becomes a factor of lowering the toughness of the steel material, and excessive addition significantly impairs the function as a mold. Therefore, the upper limit may be 0.120% for addition. ..
Ａｌ：０．０１〜０．１５％
Ａｌは、焼入性に寄与する元素であるが、不純物レベルの０．０１％未満では焼入性に寄与しない。一方、Ａｌは０．１５％より多いと、酸化物を形成し、熱間加工性を低下させる。そこで、Ａｌは０．０１〜０．１５％とする。
Al: 0.01 to 0.15%
Al is an element that contributes to hardenability, but if it is less than 0.01% of the impurity level, it does not contribute to hardenability. On the other hand, if Al is more than 0.15%, it forms an oxide and reduces hot workability. Therefore, Al is set to 0.01 to 0.15%.
９００μｍ2以上の面積を有する粗大な一次炭化物の個数が１ｍｍ2当りに４．９個以下で、かつ９００μｍ2以上の面積を有する粗大な一次炭化物の面積率が８％以下
粗大な一次炭化物の個数を１ｍｍ2当りに４．９個以下とし、面積率を８%以下に制限することで、金型としての使用時の面圧を均一に分散させ、皮膜のクラック発生を抑制することができる。
The number of coarse primary carbides having an area of 900 μm 2 or more is 4.9 or less per 1 mm 2 and the area ratio of the coarse primary carbides having an area of 900 μm 2 or more is 8% or less The number of coarse primary carbides Is 4.9 or less per 1 mm 2 and the area ratio is limited to 8% or less, so that the surface pressure during use as a mold can be uniformly dispersed and the occurrence of cracks in the film can be suppressed.
上記の一次炭化物の条件を満たす鋼材に、ＴＤ処理による表面皮膜あるいはＰＶＤ処理による表面皮膜の形成を行なう。
一次炭化物の条件を満たす鋼材へのＴＤ処理あるいはＰＶＤ処理により生成した表面皮膜のスクラッチ試験において、垂直荷重の臨界荷重が、ＴＤ処理による表面皮膜で１０１Ｎ以上あるいはＰＶＤ処理による表面皮膜で１１７Ｎ以上であるので、極めて高密着性の表面処理皮膜が形成されている。
A steel film satisfying the above-mentioned primary carbide condition is formed with a surface coating by TD treatment or a PVD treatment.
In a scratch test of a surface coating produced by TD treatment or PVD treatment on a steel material that satisfies the condition of primary carbide, the critical load of vertical load is 101 N or more for the surface coating by TD treatment or 117 N or more for the surface coating by PVD treatment. Therefore, a surface treatment film having extremely high adhesion is formed.
次いで、本願発明の化学組成であるＣｒおよびＭｏの添加量に対するＣ添加量の限定式である［Ｃ％］／Ｃｅｑの値をＲ値とするとき、本発明において１．５０≦Ｒ値≦１．８０を満足する。そこで、この１．５０≦Ｒ値≦１．８０限定理由について以下に説明する。 Next, when the value of [C%]/Ceq, which is the limiting expression of the C addition amount with respect to the addition amounts of Cr and Mo, which are the chemical compositions of the present invention, is defined as the R value, 1.50≦R value≦1 in the present invention Satisfies .80. Therefore, the reason for limiting 1.50≦R value≦1.80 will be described below.
Ｒ値は、Ｒ値＝０．９８３×［％Ｃ］／Ｃｅｑ、Ｃｅｑ＝０．０６３×［％Ｃｒ］＋０．０９３×［％Ｍｏ］で定義される。この１．５０≦Ｒ値≦１．８０は、本願発明鋼を１０３０℃から焼入れ後４９０〜５１０℃で焼戻しをした場合において、いずれかの焼戻しで５８ＨＲＣ以上を確保しつつ、靭性２５Ｊ／ｃｍ2以上の鋼材とするために必要な値である。ところで、焼戻し時には、炭化物が析出する。しかし、この炭化物の種類は焼入焼戻し硬さに多大の影響をおよぼし、特にＭｏは焼入焼戻し時に二次炭化物を析出し硬さの向上に有効である。そこで、Ｍｏ主体の炭化物を効果的に析出させるためには、本発明の範囲内においては、Ｍｏの添加量に加えてＭｏとＣｒとの添加量の関係を制御する必要がある。さらに、同時に靭性も確保するためには、ＭｏとＣｒとの添加量に対するＣ量を制御する必要がある。さらには、ＣｒとＭｏの添加量に対するＣの添加量バランスに配慮することで、高価なＭｏの添加量を最小限に抑えることができる。そこで、本発明の成分範囲で１．５０≦Ｒ値≦１．８０とする。望ましくは、１．５０≦Ｒ値≦１．７５とする。 The R value is defined by R value=0.983×[%C]/Ceq, Ceq=0.063×[%Cr]+0.093×[%Mo]. This 1.50 ≤ R value ≤ 1.80 means that when the present invention steel is tempered from 1030°C and then tempered at 490 to 510°C, a toughness of 25 J/cm 2 while maintaining 58HRC or more by any tempering. It is a value necessary to obtain the above steel materials. By the way, carbides precipitate during tempering. However, the type of this carbide has a great influence on the quenching and tempering hardness, and especially Mo is effective in improving the hardness by precipitating secondary carbides during quenching and tempering. Therefore, in order to effectively precipitate the carbide containing Mo as a main component, it is necessary to control the relationship between the addition amounts of Mo and the addition amounts of Mo and Cr within the scope of the present invention. Furthermore, in order to secure toughness at the same time, it is necessary to control the amount of C with respect to the amounts of addition of Mo and Cr. Furthermore, the amount of expensive Mo added can be minimized by considering the balance of the amount of C added with respect to the amounts of Cr and Mo added. Therefore, 1.50≦R value≦1.80 in the component range of the present invention. Desirably, 1.50≦R value≦1.75.
一方、Ｈ値は、Ｈ値＝［％Ｃｒ］／（１．８４×［％Ｍｎ］＋３．４４×［％Ａｌ］）で定義される。鋼Ｈ値が１０．０より高いと、本願の鋼材としての靱性が不足する。そこで、［％Ｃｒ］／（１．８４×［％Ｍｎ］＋３．４４×［％Ａｌ］）のＨ値は、１０．０以下とする。 On the other hand, the H value is defined by H value=[%Cr]/(1.84×[%Mn]+3.44×[%Al]). When the steel H value is higher than 10.0, the toughness of the steel material of the present application is insufficient. Therefore, the H value of [%Cr]/(1.84×[%Mn]+3.44×[%Al]) is 10.0 or less.
ここで、本願発明の実施の形態について、以下の表１に示す本発明鋼のＦｅおよび不可避不純物を除く、記号Ａ〜Ｍの１３種の実施例の合金組成およびＲ値とＨ値および比較鋼の記号ａ〜ｎの合金組成およびＲ値とＨ値、並びに表２に示す本発明鋼の記号Ａ〜Ｍの実施例の焼入焼戻硬さ、耐摩耗性、靱性、一次炭化物個数、一次炭化物面積率、表面処理性および比較鋼の記号ａ〜ｎの１４種の焼入焼戻硬さ、耐摩耗性、靱性、一次炭化物個数、一次炭化物面積率、表面処理性の各評価を通じて記載することとする。 Here, regarding the embodiments of the present invention, alloy compositions, R values and H values of 13 kinds of examples of symbols A to M, excluding Fe and inevitable impurities of the present invention steels shown in Table 1 below, and comparative steels Alloy compositions and R and H values of symbols a to n, and quenching and tempering hardness, wear resistance, toughness, number of primary carbides, primary values of the examples of symbols A to M of the steel of the present invention shown in Table 2. Carbide area ratio, surface treatability and quenching and tempering hardness of 14 kinds of symbols a to n of comparative steels, wear resistance, toughness, number of primary carbides, primary carbide area ratio, and surface treatment properties are described. I will.
先ず、表１に示す本発明鋼のＡ〜Ｍの１３種と比較鋼のａ〜ｎの１４種に示す化学成分とＦｅおよび不可避不純物からなる鋼のそれぞれ１トンを、真空溶解炉を用いて溶製してインゴットに造塊した。当該インゴットを１１２５℃に加熱して、熱間鍛造により鍛練成形比が凡そ６Ｓとなる１０５ｍｍの厚さで幅が２１５ｍｍで長さが８００ｍｍの平角材を製造した。 First, using a vacuum melting furnace, 1 ton of each of the steels consisting of Fe and inevitable impurities, and the chemical components shown in Tables 1 to 13 of the steels A to M of the present invention and 14 of the comparative steels a to n were used. It was melted and cast into an ingot. The ingot was heated to 1125° C. and hot-forged to produce a flat bar having a thickness of 105 mm, a width of 215 mm, and a length of 800 mm, which has a wrought forming ratio of about 6S.
先ず、表１について説明する。この表１には、本発明鋼の記号Ａ〜Ｍおよび比較鋼の記号ａ〜ｎに示す質量％で示す合金組成（ただし、この合金組成の表１に記載は無いが、Ｆｅと残部不可避不純物が含まれている。）とＲ値とＨ値が示されている。ただし、
Ｒ値＝０．９８３×［％Ｃ］／Ｃｅｑ
、Ｃｅｑ＝０．０６３×［％Ｃｒ］＋０．０９３×［％Ｍｏ］である。Ｈ値＝［％Ｃｒ］／（１．８４×［％Ｍｎ］＋３．４４×［％Ａｌ］）
である。
First, Table 1 will be described. In this Table 1, alloy compositions represented by mass% shown by symbols A to M of the present invention steel and symbols a to n of comparative steels (however, although not shown in Table 1 of this alloy composition, Fe and the balance unavoidable impurities) Is included) and the R and H values are shown. However,
R value = 0.983 x [% C]/Ceq
, Ceq=0.063×[%Cr]+0.093×[%Mo]. H value=[%Cr]/(1.84×[%Mn]+3.44×[%Al])
Is.
表１において、本発明鋼の１３種では、Ｒ値は本発明鋼Ｉの１．５０〜本発明鋼Ｍの１．８０であり、１．５０≦Ｒ値≦１．８０を満足する。これに対して、比較鋼ａ〜ｎの１４種の中では、比較鋼ａはＲ値が１．３８で本発明鋼のＲ値の最低値の１．５０より低く、比較鋼ｃの１．８７、比較鋼ｅの２．０７、比較鋼ｈの１．８４、比較鋼ｎの１．８６はいずれも本発明鋼のＲ値の最高値の１．８０より高い。なお、表１において、合金組成（質量％）の欄のハイフンは含有する元素が含まれないことを示し、ハイフン以外の数値は各元素の質量％で示す量である。 In Table 1, among the 13 types of the invention steels, the R value is 1.50 of the invention steel I to 1.80 of the invention steel M, and satisfies 1.50≦R value≦1.80. On the other hand, among the 14 types of comparative steels a to n, the comparative steel a has an R value of 1.38, which is lower than the minimum R value of 1.50 of the present invention steel, and 1. 87, Comparative Steel e 2.07, Comparative Steel h 1.84, and Comparative Steel n 1.86 are all higher than the highest R value of the invention steel, 1.80. In Table 1, a hyphen in the column of alloy composition (mass %) indicates that the contained element is not included, and the numerical values other than the hyphen are the amounts indicated by mass% of each element.
さらに、表１において、本発明鋼の１３種では、Ｈ値は本発明鋼Ｂの３．７〜本発明鋼Ｊの８．５であり、Ｈ値≦１０を満足する。これに対して、比較鋼ａ〜ｎの１４種の中では、比較鋼ａはＨ値が１６．９、比較鋼ｂはＨ値が１６．１、比較鋼ｌは１０．２で、発明鋼のＨ値の最高値の１０より高い。 Further, in Table 1, in the 13 types of the present invention steels, the H value is 3.7 of the present invention steel B to 8.5 of the present invention steel J, and the H value ≦10 is satisfied. On the other hand, among the 14 kinds of comparative steels a to n, the comparative steel a has an H value of 16.9, the comparative steel b has an H value of 16.1, and the comparative steel l has 10.2. It is higher than the highest H value of 10.
表２に示す、焼入焼戻し硬さの評価としては、上記作製の１０５ｍｍの厚さで幅が２１５ｍｍで長さ８００ｍｍの各平角材を１０３０℃で３０分均熱した後に、空冷による焼入れを施し、４９０〜５１０℃の焼戻温度にて２回の焼戻しを行った後、中央部を厚さ２５ｍｍ、幅２５ｍｍ、長さ２５ｍｍに切断して得た切断面を測定面とし、これらの測定面の熱影響層と、その反対面の表面にあるスケール層を平面研磨機にて除去して平行精度を高めた後、ロックウェル硬度計にて上記切断面の硬さを測定した値である。なお、焼入焼戻し硬さの測定値（ＨＲＣで示す。）はそれぞれの鋼材で得られた硬さの５点平均値を示しており、その時の焼戻しの温度を焼戻温度（℃）として示している。本発明鋼では、焼入焼戻硬さはＨＲＣで５８．０以上である。なお、表２では記号Ｅは欠いている。 As the evaluation of the quenching and tempering hardness shown in Table 2, each flat rectangular member having a thickness of 105 mm, a width of 215 mm and a length of 800 mm prepared above was soaked at 1030° C. for 30 minutes, and then quenched by air cooling. , A tempering temperature of 490 to 510° C., and then a central portion was cut into a thickness of 25 mm, a width of 25 mm, and a length of 25 mm, and the obtained cut surface was used as a measurement surface. The heat affected layer and the scale layer on the surface opposite to the heat affected layer were removed by a plane grinder to improve parallel accuracy, and then the hardness of the cut surface was measured by a Rockwell hardness meter. In addition, the measured value of quenching and tempering hardness (indicated by HRC) indicates a five-point average value of the hardness obtained for each steel material, and the tempering temperature at that time is indicated as the tempering temperature (°C). ing. In the steel of the present invention, the quenching and tempering hardness is 58.0 or more in HRC. The symbol E is omitted in Table 2.
耐摩耗性の評価としては、大越式迅速摩耗試験による比摩耗量（ｍｍ3／Ｎ・ｍｍ）を評価した。これは、上記作製の１０５ｍｍの厚さで幅が２１５ｍｍで長さ８００ｍｍの各平角材の中周部から、幅１０ｍｍ、厚さ２８ｍｍ、長さ６０ｍｍの試験片鋼材を、幅１０ｍｍ、厚さ２８ｍｍの面が鋼材の鍛伸方向と垂直方向になるように採取し、この採取した素材を１０３０℃で３０分均熱した後に、空冷による焼入れを施し、４９０〜５１０℃の焼戻温度にて２回の焼戻しを行ない、最高硬さに調質した。その後、該素材を幅７ｍｍ、厚さ２５ｍｍ、長さ５０ｍｍに仕上げ加工し、厚さ２５ｍｍ、長さ５０ｍｍの面を試験面とする試験片とした。一方、硬さが８６ＨＲＢであるＪＩＳ規格のクロムモリブデン鋼のＳＣＭ４２０からなるリング材を試験片の相手材とし、この相手材であるリング材を、最終荷重６１．８Ｎ、すべり速度２．４ｍ／ｓ、摩擦係数２００ｍの条件で、試験片と摩擦させ、試験後の比摩耗量を評価の指標とした。本発明鋼では、耐摩耗性における比摩耗量は３．０（×１０-7ｍｍ2／ｋｇ）未満である。 As the evaluation of wear resistance, the specific wear amount (mm 3 /N·mm) by the Ogoshi type rapid wear test was evaluated. This is a test piece steel material having a width of 10 mm, a thickness of 28 mm, and a length of 60 mm, and a width of 10 mm and a thickness of 28 mm. The surface of the steel is sampled so that it is perpendicular to the forging direction of the steel, and the sampled material is soaked at 1030° C. for 30 minutes, then quenched by air cooling, and tempered at 490 to 510° C. After tempering once, it was tempered to the maximum hardness. Then, the raw material was finished into a width of 7 mm, a thickness of 25 mm, and a length of 50 mm to obtain a test piece having a surface having a thickness of 25 mm and a length of 50 mm as a test surface. On the other hand, a ring material made of JIS standard chrome molybdenum steel SCM420 having a hardness of 86HRB was used as the mating material of the test piece, and the mating ring material was subjected to a final load of 61.8 N and a sliding speed of 2.4 m/s. The test piece was rubbed under the condition of a friction coefficient of 200 m, and the specific wear amount after the test was used as an evaluation index. In the steel of the present invention, the specific wear amount in wear resistance is less than 3.0 (×10 −7 mm 2 /kg).
靱性の評価としては、シャルピー衝撃試験により破壊に要したエネルギーで評価した。この試験では、１０５ｍｍの厚さで幅が２１５ｍｍで長さ８００ｍｍの各平角材の中心部から、鍛伸方向に対して、垂直方向が試験片の長さ方向になるように、１辺が１２ｍｍ四方で長さが６０ｍｍの試験片素材を採取した。これらの試験片素材を１０３０℃で３０分間の均熱を行った後、空冷により焼入れを施し４９０〜５１０℃の焼戻温度にて２回の焼戻しを行なうことで、ＨＲＣ５８〜６０に調質した。さらにその後、これらの素材を１辺が１０ｍｍ四方で長さが５５ｍｍの角柱に仕上げ加工し、鍛伸方向に垂直となる面にノッチ半径１０ｍｍ、深さ２ｍｍのＣノッチを加工して試験片としたものを用いてシャルピー衝撃試験を行った。衝撃試験値は破壊に要した衝撃エネルギーを試験片断面積で除した値であり、単位をＪ／ｃｍ2で示している。本発明鋼では、靱性における１０Ｒ−Ｃ試験片の衝撃値は２５.０（Ｊ／ｃｍ2）以上である。 The toughness was evaluated by the energy required for fracture by the Charpy impact test. In this test, one side is 12 mm so that the direction perpendicular to the forging direction is the length direction of the test piece from the center of each flat bar having a thickness of 105 mm, a width of 215 mm, and a length of 800 mm. A test piece material having a length of 60 mm on each side was sampled. These test piece materials were soaked at 1030° C. for 30 minutes, quenched by air cooling, and tempered twice at a tempering temperature of 490 to 510° C., so as to be HRC 58 to 60. .. After that, these materials are finished into prisms with a side of 10 mm square and a length of 55 mm, and a C notch with a notch radius of 10 mm and a depth of 2 mm is machined on a surface perpendicular to the forging direction to obtain a test piece. A Charpy impact test was conducted using the above. The impact test value is a value obtained by dividing the impact energy required for breaking by the cross-sectional area of the test piece, and the unit is indicated by J/cm 2 . In the steel of the present invention, the impact value of the 10R-C test piece in toughness is 25.0 (J/cm 2 ) or more.
熱間加工性の評価としては、熱間での圧縮試験により評価した。これは１０５ｍｍの厚さで幅が２１５ｍｍで長さ８００ｍｍの各平角材の焼なまし材の中心部より、直径が６ｍｍで長さが９ｍｍの円柱試験片を割出し、１１７５℃に加熱した状態で、１００ｍｍ／ｓの加工速度により加工率７０％の圧縮を行った時の、試験片の割れ発生の有無により目視にて評価した。○は割れ発生がないものであり、×は割れを生じたものである。本発明鋼では全てにおいて○である。 The hot workability was evaluated by a hot compression test. This is a state in which a cylindrical test piece with a diameter of 6 mm and a length of 9 mm was indexed from the center of each annealed material of each rectangular material having a thickness of 105 mm, a width of 215 mm and a length of 800 mm, and heated to 1175°C. Then, when the compression rate of 70% was performed at a processing speed of 100 mm/s, the presence or absence of cracking of the test piece was visually evaluated. ◯ means that no cracking occurred, and x means that cracking occurred. All of the steels of the present invention are ◯.
一次炭化物の個数の評価としては、粗大な一次炭化物の個数を１ｍｍ2当りに本発明鋼では４．９個以下であるとし、さらに一次炭化物の面積の評価としては、粗大な一次炭化物の面積率を本発明鋼では８％以下に制限することで、金型としての使用時の面圧を均一に分散させ、皮膜のクラック発生を抑制することができる。 For the evaluation of the number of primary carbides, the number of coarse primary carbides per 1 mm 2 was 4.9 or less in the steel of the present invention, and for the area of primary carbides, the area ratio of coarse primary carbides was evaluated. In the steel of the present invention, by limiting the content to 8% or less, it is possible to uniformly disperse the surface pressure during use as a mold and suppress the occurrence of cracks in the film.
ＴＤ処理あるいはＰＶＤ処理による評価としては、ＴＤ処理あるいはＰＶＤ処理により生成させた表面皮膜の垂直荷重の臨界荷重が、本発明鋼では、ＴＤ処理によるもので１０１Ｎ以上あるいはＰＶＤ処理によるもので１１７Ｎ以上であり、極めて高密着性の表面処理皮膜が形成されている。 As the evaluation by TD treatment or PVD treatment, the critical load of vertical load of the surface coating produced by TD treatment or PVD treatment is 101 N or more by TD treatment or 117 N or more by PVD treatment in the steel of the present invention. Yes, a surface treatment film with extremely high adhesion is formed.
本発明鋼Ａ〜Ｍの表２の評価は、焼入焼戻硬さがＨＲＣで５８．０〜６１．０で５８．０以上を満足し、耐摩耗性の比摩耗量が３．０（×１０-7ｍｍ2／ｋｇ）未満であり、靱性が１０Ｒ−Ｃ試験片の衝撃値が２５.０（Ｊ／ｃｍ2）未満であり、熱間加工性が試験片の割れ発生率がなくすべて○であり、一次炭化物の個数を１ｍｍ2当りに４．９個以下であり、一次炭化物の面積率は８％以下であり、ＴＤ処理あるいはＰＶＤ処理による生成の表面皮膜の垂直荷重の臨界荷重がＴＤ処理によるもので１０１Ｎ以上あるいはＰＶＤ処理によるもので１１７Ｎ以上で極めて高密着性の表面処理皮膜が形成されている。 In the evaluation of Table 2 of the invention steels A to M, the quenching and tempering hardness is 58.0 to 61.0 in HRC, which satisfies 58.0 or more, and the specific wear amount of wear resistance is 3.0 ( X 10 -7 mm 2 /kg), the toughness of the 10R-C test piece is less than 25.0 (J/cm 2 ), and the hot workability of the test piece is free from the crack occurrence rate. All are ○, the number of primary carbides is 4.9 or less per 1 mm 2 , the area ratio of primary carbides is 8% or less, and the critical load of the vertical load of the surface film produced by TD treatment or PVD treatment. Is 101 N or more by TD treatment or 117 N or more by PVD treatment, and a surface treatment film having extremely high adhesion is formed.
これに対して比較鋼ａ〜ｎの１４種では、比較鋼ａは合金組成のＭｎが０．２４％と低く、Ｒ値も１．３８と低く、Ｈ値が１６．９と高いため、１０Ｒ−Ｃ試験片の衝撃値が２３．４Ｊ／ｃｍ2と低く靱性が悪い。 On the other hand, among the 14 types of comparative steels a to n, the comparative steel a has a low Mn of alloy composition of 0.24%, a low R value of 1.38, and a high H value of 16.9. The impact value of the -C test piece was as low as 23.4 J/cm 2 and the toughness was poor.
比較鋼ｂは合金組成のＭｎが０．１６％と低く、Ｈ値が１６．１と高いため、１０Ｒ−Ｃ衝撃値が２４．６Ｊ／ｃｍ2と低く靱性が悪い。 Comparative steel b has a low Mn of alloy composition of 0.16% and a high H value of 16.1, and therefore has a low 10R-C impact value of 24.6 J/cm 2 and poor toughness.
比較鋼ｃは合金組成のＭｎが１．１０％と高く、Ｒ値も１．８７と高く、１０Ｒ−Ｃ試験片の衝撃値が２２．９Ｊ／ｃｍ2と低く靱性が悪く、熱間加工性も×である。 Comparative steel c had a high Mn of alloy composition of 1.10%, a high R value of 1.87 and a low impact value of 10R-C test piece of 22.9 J/cm 2 , poor toughness and hot workability. Is also x.
比較鋼ｄは合金組成のＭｎが１．２４％と高く、熱間加工性が×である。 Comparative steel d has a high Mn of alloy composition of 1.24% and has a hot workability of x.
比較鋼ｅは合金組成のＣｒが５．６４％と低く、形成される炭化物総量が不足するため比摩耗量が３．１（×１０-7ｍｍ2／ｋｇ）と高くなり耐摩耗性が低く、Ｒ値が２．０７と高く、１０Ｒ−Ｃ衝撃値が１８．７Ｊ／ｃｍ2と低く靱性が悪い。 Comparative Steel e has a low Cr of alloy composition of 5.64% and the total amount of carbides formed is insufficient, resulting in a high specific wear amount of 3.1 (×10 -7 mm 2 /kg) and low wear resistance. , R value is as high as 2.07, 10R-C impact value is as low as 18.7 J/cm 2, and toughness is poor.
比較鋼ｆは合金組成のＣｒが８．３６％と高く、焼入焼戻硬さがＨＲＣで５６．８と低く、耐摩耗性の比摩耗量が３．７（×１０-7ｍｍ2／ｋｇ）と高く耐摩耗性が悪く、一次炭化物の個数が５．４個と高く、ＴＤ処理膜の臨界荷重が６４Ｎであり、さらにＰＶＤ処理の臨界荷重が７９Ｎであり、表面処理性が悪い。 Comparative steel f has a high Cr of 8.36% in the alloy composition, a low quenching and tempering hardness of 56.8 in HRC, and a specific wear amount of wear resistance of 3.7 (×10 -7 mm 2 / Kg), the wear resistance is poor, the number of primary carbides is as high as 5.4, the critical load of the TD-treated film is 64 N, and the critical load of the PVD treatment is 79 N, and the surface treatability is poor.
比較鋼ｇは合金組成のＣが０．７３％と低く、焼入焼戻硬さがＨＲＣで５７．１と低く、耐摩耗性の比摩耗量が３．１（×１０-7ｍｍ2／ｋｇ）と高く耐摩耗性が悪い。 Comparative steel g had a low alloy composition C of 0.73%, a low quenching and tempering hardness of HRC of 57.1, and a specific wear resistance of 3.1 (×10 -7 mm 2 / High wear resistance.
比較鋼ｈは合金組成のＣが０．９６％と高く、炭化物の偏析が増加することで、１０Ｒ−Ｃ試験片の衝撃値が１４.８（Ｊ／ｃｍ2）と靱性が低く、Ｒ値が１．８４と高く、熱間加工性が試験片の割れ発生率が多く×であり、一次炭化物の個数を１ｍｍ2当りに６．７個と多く、一次炭化物の面積率は８５％で高く、ＴＤ処理あるいはＰＶＤ処理による生成の表面皮膜の垂直荷重の臨界荷重がＴＤ処理によるもので５４ＮあるいはＰＶＤ処理によるもので６９Ｎと極めて低く密着性に劣る表面処理皮膜が形成されている。 Comparative steel h has a high C of 0.96% in the alloy composition, and the segregation of carbides increases, and the impact value of the 10R-C test piece is 14.8 (J/cm 2 ) and the toughness is low. Is as high as 1.84, the hot workability is high in the crack occurrence rate of the test piece, and the number of primary carbides is as high as 6.7 per 1 mm 2 , and the area ratio of primary carbides is as high as 85%. The surface treatment film formed by TD treatment or PVD treatment has a critical vertical load of 54 N due to TD treatment or 69 N due to PVD treatment, and a surface treatment film having poor adhesion is formed.
比較鋼ｉは合金組成のＳｉが０．２０％と低く、鋼材自体の強度が得られず、焼入焼戻硬さがＨＲＣで５７．１と低く、比摩耗量が３．２（×１０-7ｍｍ2／ｋｇ）と高く耐摩耗性悪く、１０Ｒ−Ｃ試験片の衝撃値が２２．８（Ｊ／ｃｍ2）と靱性が低い。 In Comparative Steel i, the alloy composition Si was low at 0.20%, the strength of the steel material itself could not be obtained, the quenching and tempering hardness was low at HRC 57.1, and the specific wear amount was 3.2 (×10 -7 mm 2 /kg) and poor wear resistance, and the 10R-C test piece has an impact value of 22.8 (J/cm 2 ) and low toughness.
比較鋼ｊはＳｉ含有量が１．１５％と高く、基地組織の延性が低下するため、１０Ｒ−Ｃ衝撃値が２１．１Ｊ／ｃｍ2で靱性が低い。 Comparative Steel j has a high Si content of 1.15% and the ductility of the matrix structure decreases, so the 10R-C impact value is 21.1 J/cm 2 and the toughness is low.
比較鋼ｋはＳ含有量が０．１６３％と高く、硫化物が過剰に生成されるために、１０Ｒ−Ｃ試験片の衝撃値が２３．２Ｊ／ｃｍ2で靱性が低く、かつ熱間加工性が×で悪い。 Comparative steel k has a high S content of 0.163% and excessive sulfides are produced, so that the impact value of the 10R-C test piece is 23.2 J/cm 2 and the toughness is low, and hot working is performed. The sex is bad and bad.
比較鋼ｌはＭｏ含有量が０．１５％と低く、有用なＭｏ系の炭化物が減少し、焼入焼戻硬さが５７．２ＨＲＣと低く、比摩擦量が３．６８（×１０−７ｍｍ2／ｋｇ）と高いので耐摩耗性が低く、Ｈ値が１０．２と高いため、１０Ｒ−Ｃ試験片の衝撃値が２４．１Ｊ／ｃｍ2と低いので靱性が低く、また熱間加工性が×で、また粗大な一次炭化物の面積率が８．４％と増加することで、ＴＤ処理膜のダイヤモンド圧子によるスクラッチ試験の臨界荷重が５６Ｎで低く、ＰＶＤ処理膜の同スクラッチ試験の臨界荷重が８３Ｎで低く、表面処理性が低い。 Comparative steel 1 has a low Mo content of 0.15%, reduces useful Mo-based carbides, has a low quenching and tempering hardness of 57.2HRC, and has a specific friction amount of 3.68 (×10 −7 ). mm 2 /kg), the wear resistance is low, and the H value is 10.2, so the impact value of the 10R-C test piece is as low as 24.1 J/cm 2 , so the toughness is low and hot working The critical load of the scratch test by the diamond indenter of the TD-treated film is low at 56N, and the criticality of the scratch test of the PVD-treated film is low, because the area ratio of coarse primary carbides increases to 8.4%. The load is low at 83 N, and the surface treatability is low.
比較鋼ｍはＭｏ含有量が０．５８％と高く、炭化物の粗大凝集が発生して１０Ｒ−Ｃ試験片の衝撃値が２３．１Ｊ／ｃｍ2と低いので靱性が低い。 Comparative steel m has a high Mo content of 0.58%, and coarse agglomeration of carbides occurs, and the impact value of the 10R-C test piece is as low as 23.1 J/cm 2 , so that the toughness is low.
比較鋼ｎはＡｌ含有量が０．１７％と高く、またＲ値も１．８６と高いため、熱間加工性が×で悪い。 The comparative steel n has a high Al content of 0.17% and a high R value of 1.86, and thus has poor hot workability.
以上のように、表２において、本発明鋼Ａ〜Ｍの１３種は、いずれも焼入焼戻し硬さはＨＲＣ５８．０以上、耐摩耗性は比摩耗量が２．９×１０-7ｍ3／Ｎ・ｍｍ以下で耐摩耗性があり、１０Ｒ−Ｃ衝撃値が２５．２Ｊ／ｃｍ2以上で靱性があり、したがって、これらは十分な焼入焼戻硬さ、靭性を有し、かつ耐摩耗性を兼備している。これらの本発明鋼Ａ〜Ｍの１３種は、ＣｒとＭｎの添加量バランスに配慮することで、高価なＣｒの添加量を最小限に抑え、同様に高価な元素であるＶについては積極的な添加を必要とせずとも、これらの鋼は、冷間プレス金型などの冷間成形用工具として必要な表２に示す特性を満たすことにより、比較的に安価な冷間工具鋼を需要企業に提供することが可能となった。 As described above, in Table 2, the 13 types of the invention steels A to M all have a quenching and tempering hardness of HRC 58.0 or more and a wear resistance of a specific wear amount of 2.9×10 −7 m 3. /N·mm or less has wear resistance, and 10R-C impact value is 25.2 J/cm 2 or more and has toughness. Therefore, these have sufficient quenching and tempering hardness, toughness, and It also has abrasion resistance. These 13 steels of the present invention steels A to M, by considering the balance of the amounts of addition of Cr and Mn, minimize the amount of expensive Cr added, and are also positive about V, which is also an expensive element. These steels, which do not require any special addition, satisfy the characteristics shown in Table 2 necessary for cold forming tools such as cold press dies, so that relatively inexpensive cold tool steels are in demand. It is now possible to provide.
Claims (3)
ただし、上記の［％元素］は元素量で、質量％を示し、Ｒ値およびＨ値は以下に示すとおりである。
Ｒ値＝０．９８３×［％Ｃ］／Ｃｅｑ、
ただし、Ｃｅｑ＝０．０６３×［％Ｃｒ］＋０．０９３×［％Ｍｏ］・・・式（１）
Ｈ値＝［％Ｃｒ］／（１．８４×［％Ｍｎ］＋３．４４［％Ａｌ］・・・式（２） % By mass, C: 0.75 to 0.90%, Si: 0.30 to 0.90%, Mn: 0.35 to 1.00%, Cr: 5.70 to 8.20%, Mo: 0.20 to 0.50%, Al: 0.01 to 0.15%, the balance consisting of Fe and inevitable impurities, and the R value in formula (1) is 1.50≦R value≦1. 80, the H value in the formula (2) is H value≦10.0, the number of carbides having an area of 900 μm 2 or more is 4.9 or less per 1 mm 2 , and the area of carbide having an area of 900 μm 2 or more. Steel for cold press dies, characterized in that the ratio is 8% or less.
However, the above [% element] is an element amount and represents% by mass, and the R value and the H value are as shown below.
R value = 0.983 x [%C]/Ceq,
However, Ceq=0.063×[%Cr]+0.093×[%Mo] Equation (1)
H value=[%Cr]/(1.84×[%Mn]+3.44[%Al]...Equation (2)
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| JP2005187900A (en) * | 2003-12-26 | 2005-07-14 | Daido Steel Co Ltd | Cold tool steel having excellent surface treatability, component for die, and die |
| JP2014145100A (en) * | 2013-01-28 | 2014-08-14 | Sanyo Special Steel Co Ltd | Cold tool steel having reduced alloy addition amount |
| WO2014192730A1 (en) * | 2013-05-30 | 2014-12-04 | 日立金属株式会社 | Method for manufacturing mold for cold working use |
| JP6177694B2 (en) * | 2014-01-06 | 2017-08-09 | 山陽特殊製鋼株式会社 | Steel for cold press dies |
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