JPS6230852A - Extra-soft ferritic stainless steel - Google Patents

Abstract

PURPOSE:To obtain an extra-soft ferritic stainless steel having <=140 hardness Hv by reducing the amounts of Si, P, Cu, Mo and Ni in a steel and adding a specified amount of Al so as to fix N as AlN and to make the hardening action of N by the formation of a solid soln. ineffective. CONSTITUTION:The composition of a ferritic stainless steel is composed of, by weight, <0.03% C, <0.3% Si, 1.5% Mn, <0.04% P, <0.15% S, <1% Ni, <0.5% Cu, <0.6% Mo, 11.5-20% Cr, <0.03% N, 0.005-0.2% Al and the balance Fe with inevitable impurities. The composition may further contain 0.005-0.2% each among one or more of Ti, Nb and V.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は極軟質フェライ）・系ステンレスｉｎに係リ、
特に貨幣、メダル、ゲーム用コインもしくは鍵等の如く
冷間プレスにより精密な圧印加工が必要とされる各種製
品の素材として最適な極軟質フェライト系ステンレス鋼
に関する。[Detailed description of the invention] [Industrial field of application] The present invention relates to ultra-soft ferrite-based stainless steel.
In particular, the present invention relates to ultra-soft ferritic stainless steel that is ideal as a material for various products that require precise coining by cold pressing, such as coins, medals, game coins, keys, etc.

〔従来の技術〕[Conventional technology]

雑誌ｒｃｈｒｏｍｉｕｍ　ＲｅｖｉｅｗＪ　Ｎｏ、　１
　１９８３年４月号によれば１９７９年に全世界の１１
７ケ国で新たに発行されたコイン総量の５５％以上はス
テンレス鋼が使用されているという。これはコイン製造
上の経済性およびコインの流通に際しての耐久性の観点
からステンレス鋼が見方されていることを意味している
。Magazine rchromium ReviewJ No. 1
According to the April 1983 issue, in 1979 the world's 11
More than 55% of all new coins issued in seven countries are made of stainless steel. This means that stainless steel is being looked at from the viewpoint of economy in coin production and durability in coin circulation.

ステンレス鋼コインは魅力的な光沢を有し、耐食性、耐
摩耗性がすぐれており、経済的な観点からも銅合金等の
他の材料と比較して有利性を持っているが、このコイン
への適用に当って最大の問題点は、その硬さが硬いこと
にあり、そのためコイニング（圧印）時に大容量のプレ
ス能力が必要とされること、コイニング時のダイスの寿
命が短いこと等コイン製造上の種々の困難を伴うという
問題である。Stainless steel coins have an attractive luster, excellent corrosion and abrasion resistance, and are economically advantageous compared to other materials such as copper alloys. The biggest problem with its application is that it is hard, so a large press capacity is required during coining (coining), and the life of the die during coining is short. This problem involves the various difficulties mentioned above.

第１表最下段から３段目に最も古くからステンレス鋼を
素材とずろコインの製造を行っているイタリアの１００
リラコインの組成分析値と、該コインに７５０℃５分間
の焼鈍を施し再結晶状態で測定した硬さＨｖを示した。Table 1: 3rd row from the bottom shows 100 Italian coins that have been manufacturing stainless steel coins for the longest time.
The compositional analysis values of the Lila coin and the hardness Hv measured in the recrystallized state after annealing the coin at 750° C. for 5 minutes are shown.

第１図は該コインの圧印状況を示す表面形状であり、第
２図は７５％Ｃｕ−２５％Ｎｉを含む日本の１００円白
８貨幣の圧印状況を示す表面形状である。第１表より明
らかなとおり、現用イタリアのコイン用ステンレス鋼は
焼なまし状態で硬さが約Ｈｖ　１６３と硬質てあり、第
１図、第２図の比較からも明らかな如く、イタリアのス
テンレス鋼を素材とするコインは日本の白銅を素材とす
る１００円貨幣よりも表面の模様の彫りが浅く不鮮明で
ある。コインの彫りの深さは圧印用プレスの圧力を高め
ることによって改善されるが、一方高価なダイスの寿命
を短縮する結果となり経済的に得策ではない。かくの如
く、コイン用素材としてステンレス鋼の種々の利点を十
分に生かすために、先ずその硬質性を改善することが極
めて重要であることが理解されろ。FIG. 1 shows the surface shape of the coin showing the coining condition, and FIG. 2 shows the surface shape of the coining condition of 8 Japanese 100 yen white coins containing 75% Cu-25% Ni. As is clear from Table 1, the current Italian stainless steel for coins has a hardness of approximately Hv 163 in the annealed state. Coins made of steel have shallower and less clear patterns on their surfaces than Japanese 100 yen coins made of cupronickel. Although the depth of the coin engraving can be improved by increasing the pressure of the coining press, this is not economically advantageous as it shortens the life of the expensive die. As described above, it is understood that in order to fully utilize the various advantages of stainless steel as a material for coins, it is extremely important to first improve its hardness.

従来コイン用ステンレス鋼として開示されたものに特開
昭５５−８９４３１がある。この発明の要旨とするとこ
ろは、１２〜１８％のＣｒを含む７エライ１〜系ステン
レス鋼において、ＣｒＪ）外の添加元素量を可能な限り
低減したことと、素材の処理工程においてリジング性を
改善するために、その熱延に際して熱延仕上温度を８０
０℃以下とし、巻取温度を４５０℃以下に限定した点に
ある。JP-A-55-89431 has been disclosed as a stainless steel for coins. The gist of this invention is to reduce the amount of added elements other than CrJ) as much as possible in 7-element 1-series stainless steel containing 12 to 18% Cr, and to improve ridging property in the material processing process. In order to improve the hot rolling process, the hot rolling finishing temperature was set at 80°C.
The main feature is that the winding temperature is limited to 0°C or lower, and the winding temperature is limited to 450°C or lower.

１７かし、Ｃｒ以外の他の元素を低くすることは種々の
問題があり、例んばＣ，Ｎ含有量を低減させろことはコ
ストの上昇を招き、Ｓｉを低レベルに抑制することは脱
酸不足を生じコイン製造に重要な表面性状を劣化させる
こととなる。またリジング性の改善には熱延性」一温度
、巻取温度を低下させるのが有効であることは、特公昭
４９−１５６９６、特開昭５２　６６８１６１．特公昭
５８−５６０１２等により公知の技術であるが、コイン
の巻取温度を４５０’３以下の低１品とすることば熱延
材のコインの形状を極端に悪くする結果となり、コイン
用ステンレス鋼として致命的欠陥となるおそれがある。17 However, there are various problems with reducing the content of other elements other than Cr. For example, reducing the content of C and N will increase costs, and suppressing Si to a low level is not an option. This causes a lack of acid and deteriorates the surface quality, which is important for coin production. Furthermore, in order to improve the ridging property, it is effective to lower the hot ductility temperature and the coiling temperature, as disclosed in Japanese Patent Publication No. 49-15696 and Japanese Patent Application Laid-Open No. 1982-668161. This is a technique known from Japanese Patent Publication No. 58-56012, etc., but if the coiling temperature of the coin is set to a low value of 450'3 or less, the shape of the hot-rolled coin becomes extremely poor. This may result in a fatal flaw.

〔発明が解決しようとする問題点〕[Problem that the invention seeks to solve]

本発明の目的はコイン用ステンレス鋼の如く冷間−ｆレ
ス成形等によって加工されるステンレス鋼の上記従来技
術の問題点を解決し、その最大の問題点である硬質性を
改善しＨｖ　１４０以下の極軟質フエライ）・系ステン
レス鋼を提供するにある。The purpose of the present invention is to solve the above-mentioned problems of the conventional technology of stainless steel processed by cold-fless forming, such as stainless steel for coins, and to improve the hardness, which is the biggest problem, so that the hardness of the stainless steel is less than Hv 140. We provide ultra-soft stainless steel.

〔問題点を解決するための手段〕 本発明の上記の目的は次の２発明によって達成される。[Means for solving problems] The above objects of the present invention are achieved by the following two inventions.

第１発明の要旨とするところは次の如くである。すなわ
ら、 重量比にて　Ｃ：０．０３％未満 Ｓｉ：０．３０％以下 Ｍｎ：１．５％以下 Ｐ：０．０４％以下 Ｓ：０．１５％以下 Ｎｉ：１．０％以下 Ｃｕ：０．５０％以下 Ｍｏ：０．６０％以下 Ｃｒ：　　１１．５〜２０％ Ｎ：０．０３％以下 Ａｌ：０．００５〜０．２０％ を含有し、残部はＦｅおよび不可避的不純物より成り、
硬度がビッカース硬度スケールて１４０以下てあり圧印
加工性に侵れたことを特徴とする極軟質フェライト系ス
テンレス鋼である。The gist of the first invention is as follows. That is, in weight ratio: C: less than 0.03% Si: 0.30% or less Mn: 1.5% or less P: 0.04% or less S: 0.15% or less Ni: 1.0% or less Cu: 0.50% or less Mo: 0.60% or less Cr: 11.5-20% N: 0.03% or less Al: 0.005-0.20% The remainder is Fe and inevitable impurities. It consists of
It is an extremely soft ferritic stainless steel characterized by a hardness of 140 or less on the Vickers hardness scale and poor coining workability.

第２発明の要旨とするところは第１発明と同一基本組成
のほかに、更にＴｉ：０．００５〜０２０％、Ｎｂ：　
　ｏ、ｏ　Ｏ５〜０．２０％、ｖ：　０００５〜０２０
％の中から選ばれた１種以上を含み残部はＦｅおよび不
可避的不純物より成り、硬度がビッカース硬度スケール
で１４０以下であり圧印加工性に擾れたことを特徴とす
る極軟質フェライト系ステンレス鋼である。The gist of the second invention is that in addition to the same basic composition as the first invention, Ti: 0.005-020%, Nb:
o, o O5~0.20%, v: 0005~020
%, the remainder is Fe and unavoidable impurities, the hardness is 140 or less on the Vickers hardness scale, and the coining workability is poor. It is.

本発明者らは、フェライト系ステンレス鋼の軟質化を図
るに当って、先ずＣ，Ｓｉ　、ＭｎＸＰＸＳ。In attempting to soften ferritic stainless steel, the present inventors first used C, Si, and MnXPXS.

Ｃｒ、　Ｎｉ　、Ｃｕ、　Ｍｏ、Ｎの１０元素を種々の
レベル含有する８７種類のフェライト系ステンレス鋼の
成分元素濃度と、結晶粒径がすべて２０〜３０μｍとほ
ぼ一定のもとにおけるＨｖ硬さとの相関分析を行った結
果下記の（１）式を得ることができた。The relationship between the component element concentration of 87 types of ferritic stainless steel containing various levels of the 10 elements Cr, Ni, Cu, Mo, and N and the Hv hardness when the grain size is all approximately constant at 20 to 30 μm. As a result of correlation analysis, the following equation (1) could be obtained.

Ｈｖ＝７３．３　１２．３（５（Ｃ）＋２２．７（ＸＳ
ｉ）→−０，８（２Ｍｎ）→−３６１（ＺＰ）−５５１
（２Ｓ）＋２．９　（ｊ；Ｃｒ）＋２６　（ＸＮｉ）＋
　９　、８　（ＸＣｕ）　＋　５　、１　ＫＭｏ）　＋
　３７０　（１）−−−−４１１上記（１）式からＳＵ
Ｓ　４３０に代表されろ通常のフェライト系ステンレス
鋼に含まれる各元素の濃度レベルと上記（１）式の係数
の大きさからＨｖ硬さを低下させるためには、特にフェ
ライト系ステンレス鋼の主要元素としてＳｉ　、Ｐ、　
Ｃｕ　、、Ｍｏ、Ｎの５成分を規制すべきであることが
判明した。Hv=73.3 12.3(5(C)+22.7(XS
i) → -0,8 (2Mn) → -361 (ZP) -551
(2S)+2.9 (j;Cr)+26 (XNi)+
9, 8 (XCu) + 5, 1 KMo) +
370 (1)---411 From the above formula (1), SU
In order to reduce the Hv hardness based on the concentration level of each element contained in ordinary ferritic stainless steel, such as S430, and the magnitude of the coefficient in equation (1) above, it is necessary to As Si, P,
It was found that five components, Cu, Mo, and N, should be regulated.

ところで一般にＣは便さを増加させる元素であるが、上
記（１）式ではむしろ負の係数を有している結果となっ
ている。この理由は、フェライト系ステンレス鋼の通常
の処理を経た後ではＣはＣｒ　　Ｃ等のＣｒ炭化物とし
て析出しており、そのためＣ元素本来の固溶硬化作用は
生ぜず、むしろ固溶硬化作用を与えるＣｒａ度を実質的
に下げることを通して軟化作用を与えることによるもの
と考えられる。By the way, C is generally an element that increases convenience, but in the above equation (1), the result is that it has a rather negative coefficient. The reason for this is that after the normal treatment of ferritic stainless steel, C precipitates as Cr carbides such as CrC, so that the solid solution hardening effect inherent to C element does not occur, but rather gives a solid solution hardening effect. This is thought to be due to the fact that it provides a softening effect by substantially lowering the Cra degree.

本発明は上記の知見と、溶製時の経済性および素材の）
青浄度と表面性状を考慮して上記要旨の如く組成範囲を
限定することにより、極めて軟質なフェライト系ステン
レス鋼を安価に工業生産し得ることを見出し、本発明を
完成したものである。The present invention is based on the above knowledge, economical efficiency during melting, and material efficiency.
The present invention has been completed by discovering that extremely soft ferritic stainless steel can be industrially produced at low cost by limiting the composition range as outlined above in consideration of blue cleanliness and surface properties.

本発明によるフェライト系ステンレス鋼の成分限定理由
について説明する。The reason for limiting the composition of the ferritic stainless steel according to the present invention will be explained.

Ｃ： Ｃは上記の如く、硬さに対しては従来一般に考えられて
いた点とは逆に、Ｃｒ炭化物生成を通じて軟化作用をも
つことが明らかになった。それ故Ｃは通常の添加レベル
においては硬さの観点から特に規制する必要はない。し
かし、一方貨幣に適用するに当っては約１５〜２０年と
される貨幣の流通寿命期間中の十分な耐食性を有するこ
とが要求される。C: As mentioned above, it has become clear that C has a softening effect on hardness through the formation of Cr carbides, contrary to what was generally thought in the past. Therefore, C does not need to be particularly regulated from the viewpoint of hardness at a normal addition level. However, when applied to coins, it is required to have sufficient corrosion resistance during the circulation life of coins, which is about 15 to 20 years.

貨幣の耐食性に最も影響を及ぼすのは汗であると考えら
れている。本梵明者らばＳｉ：０．１０％、Ｍｎ：０．
５０％、Ｐ：Ｏ，００１％、Ｃｒ：１２．５％および１
７５％、Ａｊ：０．０５％を含有し、かつ各Ｃｒ含有量
レベルにっきＣ含有量を００１０〜００７４％に変化さ
せたステンレス鋼を溶製し、その冷延焼純板の人工汗溶
液中の孔食電位を測定し、第３図にその結果を示した。Sweat is thought to have the greatest effect on the corrosion resistance of coins. If this is the case, Si: 0.10%, Mn: 0.
50%, P:O, 001%, Cr:12.5% and 1
75%, Aj: 0.05%, and the C content was changed from 0010 to 0074% at each Cr content level. The pitting potential was measured and the results are shown in FIG.

なお、比較のため現用のイタリアコイン用ステンレス鋼
の結果も同図においてＯ印で示した。For comparison, the results for the stainless steel currently in use for Italian coins are also shown with an O mark in the same figure.

孔食電位の測定は下記のようにして行った。The pitting potential was measured as follows.

すなわち、１１の水中に７ｇのＮａＣ１，１ｇの尿素、
４ｇの乳酸を含む人工汗溶液で基準電極としてＳＣＥ　
（飽和甘木電厖）を使用してアノード分極試験を行った
。測定は３５℃の前記人工汗溶液に試料を浸漬後ＳＣＥ
による−５００　ｍＶで１０分間保持後、自然浸漬電位
で更に１０分間保持しｔ−後１分間当り２０ｍＶ宛電位
全土げてＩＶになるまて掃引した。かくして得られたア
ノード分極曲線上で孔食の発生に伴って急激な溶解を開
始し溶解電流密度が１００μＡ／ｃｔに達する電位を孔
食電位とした。That is, 7 g of NaCl, 1 g of urea in 11 water,
SCE as a reference electrode with an artificial sweat solution containing 4 g of lactic acid.
(Saturated Amagi Denku) was used to perform an anode polarization test. The measurement was carried out by SCE after immersing the sample in the artificial sweat solution at 35°C.
After holding at -500 mV for 10 minutes, the natural immersion potential was held for another 10 minutes, and after t- the entire potential was swept at 20 mV per minute until it reached IV. On the thus obtained anode polarization curve, the potential at which rapid dissolution begins with the occurrence of pitting corrosion and the dissolution current density reaches 100 μA/ct was defined as the pitting corrosion potential.

第３図から人工汗溶液中の孔食電位はＣｒ含有量によら
ずＣ含有量によって大きく影響されろことがわかるが、
良好な耐食性を得ろという観点からＣ含有量は本発明に
おいて００３％未満に限定した。００３％未満に限定す
ることにより１７５％Ｃｒ　含有レベルて現用の１′ク
リアコイン用ステンレス鋼と比較し優れた耐食性が得ら
れる。From Figure 3, it can be seen that the pitting corrosion potential in the artificial sweat solution is not affected by the Cr content, but is greatly influenced by the C content.
From the viewpoint of obtaining good corrosion resistance, the C content was limited to less than 0.03% in the present invention. By limiting the content to less than 0.003%, superior corrosion resistance can be obtained compared to the current stainless steel for 1' clear coins at a 175% Cr content level.

ＳＩ　： Ｓｉは溶製時の脱酸のため必須の成分であるが、硬度−
上昇作用が大きいために本発明ではＡＩによる脱酸を考
慮しＳｉを最少限に止め、その上限を０３０％に限定し
た。SI: Si is an essential component for deoxidizing during melting, but the hardness -
Since the increasing effect is large, in the present invention, in consideration of deoxidation by AI, Si is kept to a minimum and its upper limit is limited to 0.030%.

Ｍｎ　　・ 上記（１）式より明らかな如＜、Ｍｎは硬度を高める効
果が小さく、１％の添加によっても硬度上昇（よｔ（ｖ
て１弱で、特に厳しく規制する必要がないが、１５％を
越すと耐食性を劣化させるので上限を１５％に限定した
。Mn - As is clear from the above formula (1), Mn has a small effect of increasing hardness, and even with the addition of 1%, the hardness increases (t(v)
It is a little less than 1, so there is no need to strictly regulate it, but if it exceeds 15%, corrosion resistance will deteriorate, so the upper limit was limited to 15%.

Ｐ　： Ｐは上記（１）式に示す如く硬さ上昇係数が３６１と非
常に大きいので極力低下することが好ましいが脱酸の経
済性との兼ね合いで００４％以下に限定し１．：　。P: As shown in formula (1) above, P has a very large hardness increase coefficient of 361, so it is preferable to reduce it as much as possible, but in consideration of the economical efficiency of deoxidation, it is limited to 0.004% or less. :.

Ｓ　： Ｓは上記（１）式では負の係ｖ！、を有しており、硬、
さの低減のｔ：めに高濃度の添加が望ましいが、Ｓが０
１５％を越えて過多となると耐食性を低下させるので上
限を０１５％に限定した。S: S is a negative coefficient v! in the above equation (1). , hard,
It is desirable to add S at a high concentration to reduce t:
If the content exceeds 15%, the corrosion resistance will deteriorate, so the upper limit was set at 0.015%.

Ｎｉ　、Ｃｕ、　Ｍｏ： 上記（１）式のＮｉ　、Ｃｕ　、　Ｍｏの）（ｖ上昇係
数がそれぞれ２６．９．８．５．１であることを考慮し
てこれら３元素のＨｖ硬さの上昇の合計が約３以下にな
ることを目安として、Ｎ１ば１０％以下、Ｃす：よ０５
０％以下、Ｍｏは０６０％以下に限定した。Ni, Cu, Mo: Considering that the v increase coefficients of Ni, Cu, and Mo in equation (1) above are respectively 26.9.8.5.1, increase in Hv hardness of these three elements. As a guideline, the total of N1 is about 10% or less, and C: Yo05.
0% or less, and Mo was limited to 0.060% or less.

Ｃｒ　： Ｃｒはフェライト系ステンレス鋼の耐食性を維持するた
め最も重要な元素であり、１１．５％未満では耐食性を
維持することができず、また２０％を越して過多になる
と熱間加工性が劣化するので１１５〜２０％の範囲に限
定した。Cr: Cr is the most important element for maintaining the corrosion resistance of ferritic stainless steel. If it is less than 11.5%, corrosion resistance cannot be maintained, and if it exceeds 20%, hot workability will deteriorate. Since it deteriorates, it is limited to a range of 115 to 20%.

Ｎ　： Ｎは上記（１）式におけるＨｖ上昇係数が３７０と最大
であり低値とすることが望ましいが、本発明てはＡＩ’
　、　Ｔｉ　％　Ｎｂ　、　Ｖの適当屋を添加すること
によりＮを窒化物として固定したのでコスト上昇を来さ
ない０．０３％を上限とし００３％以下に限定した。N: The Hv increase coefficient in the above formula (1) is 370, which is the maximum, and it is desirable to set it to a low value, but in the present invention, AI'
, Ti % Nb , and V were added to fix N as a nitride, so the upper limit was set at 0.03%, which does not increase costs, and was limited to 0.03% or less.

Ａｌ： ＡＩの適正量の添加は本発明における最も著しい特徴の
一つである。本発明におけるＡＩの作用は次の如くであ
る。Al: Addition of an appropriate amount of AI is one of the most remarkable features of the present invention. The action of AI in the present invention is as follows.

（イ）　Ｈｖ硬さに最も大きく影響するＮをＡｊ’Ｎと
して固定して、その固溶硬化作用を無害化する。(a) N, which has the greatest influence on Hv hardness, is fixed as Aj'N to render its solid solution hardening effect harmless.

（０）　　Ｈｖ硬さ上昇作用の大きいＳｌを０３０％以
下に限定したことによる脱酸不十分を補い、かつ脱酸不
十分による清浄度劣化による表面性状の悪化を防止する
。(0) Compensate for insufficient deoxidation caused by limiting Sl, which has a large effect of increasing Hv hardness, to 0.30% or less, and prevent deterioration of surface properties due to deterioration of cleanliness due to insufficient deoxidation.

０５〜３％のＡＩを含むフェライト系ステンレス鋼につ
いて、上記（１）式を求めｔ：のと同一手法でＨｖ硬さ
に対するＡＩの係・数を求めた結果＋６１となり硬化作
用を有することが判明したが、一方０５％以下のＡＩの
添加の場合、原子パーセントでＮ量の３倍以下のＡＩの
添加によって固溶窒素をＡＩＮとして固溶硬化作用を抑
制することができろ。しかし、固溶ｋｌの上記（１１式
と同様のＨｖ硬化係数が＋６１であることより必要以」
二の添加はＨｖ硬さの上昇を招くので、上限を０２０％
とし、Ｎ量０．０３％以下の規制との関連から下限をｏ
、ｏｏｓ％とし、ｏ、ｏｏｓ〜０．２０％の範囲に限定
した。For ferritic stainless steel containing 0.5 to 3% AI, the above equation (1) was calculated and the coefficient of AI to Hv hardness was calculated using the same method as t:.The result was +61, indicating that it has a hardening effect. However, in the case of adding 0.5% or less of AI, it is possible to suppress the solid solution hardening effect by converting solid solution nitrogen into AIN by adding AI in an amount not more than 3 times the amount of N in terms of atomic percent. However, since the Hv hardening coefficient of the solid solution kl (similar to Equation 11) is +61, it is not necessary.
The addition of 2 causes an increase in Hv hardness, so the upper limit is set to 0.20%.
In relation to the regulation of N content of 0.03% or less, the lower limit was set to o.
, oos%, and was limited to a range of o, oos to 0.20%.

上ｎＦ、Ｃ，Ｓｉ、　　　Ｍｎ、　　　Ｐ、　　　Ｓ　
　Ｘ　　Ｎｉ　　、　　Ｃｕ、　　　Ｍｏ。Upper nF, C, Si, Mn, P, S
X Ni, Cu, Mo.

Ｃｒ、Ｎ、ｋｌの各限定量をもって本発明による極軟質
フェライト系ステンレス鋼の基本成分とするが、更にＴ
ｉ、Ｎｂ、Ｖの下記限定量の１挿置」二を同時に含有す
る場合においても、本発明の目的をより有効に達成する
ことができる。これらの限定理由は次の如くである。Limited amounts of Cr, N, and Kl are the basic components of the ultra-soft ferritic stainless steel according to the present invention, and T
Even when the following limited amounts of i, Nb, and V are simultaneously contained, the objects of the present invention can be more effectively achieved. The reasons for these limitations are as follows.

Ｔｉ　ＳＮｂ　ＸＶ： 本発明におけるＴｉ、Ｎｂ５Ｖの作用は上記の如（Ｈｖ
硬さに最も大きく影響するＮをその強力な窒化物形成作
用によりＴｉＮ、　ＮｂＮ、　ＶＮとして固定化し、そ
の固溶硬化作用を無害化することにある。これらの元素
を添加する場合はＡＩは脱酸のみを考慮した低レベルで
よいとし）う効果もある。Ti SNb XV: The action of Ti and Nb5V in the present invention is as described above (Hv
The purpose is to fix N, which has the greatest effect on hardness, as TiN, NbN, and VN through its strong nitride-forming action, and to render its solid solution hardening action harmless. When these elements are added, there is also the effect that AI may be kept at a low level considering only deoxidation.

７エライト系ステンレス鋼においては、耐食性向上の目
的で０．２０〜０６０％のＴｉ、Ｎｂ、、Ｖの添加が行
われることがある。この範ｇＨのＴ１、Ｎｂ、、ｖ量を
含むフエライ１−系ステン１／ス泪について、丘記（１
）式を求めたのと同一手法でＨｖ硬さに対するこれら３
元素の係数を求めた結果、＋１１２、＋１７２、＋７４
と算出され大きな硬化作用を有することが判明した。し
かし０２％以下のＴｉ、Ｎｂ、Ｖの添加の場合、原子パ
ーセン）・てＮｚの約３＠以下のＴｉ、Ｎｂ、Ｖの添加
によって実質的に固溶窒素を窒化物として固溶硬化作用
を抑制ずろことができ、かつ著しい硬化作用を発揮ずろ
固溶Ｔｉ、Ｎｂ、Ｖを無視できるレベルに保つことがで
きることが判明した。In 7-elite stainless steel, 0.20 to 0.60% of Ti, Nb, and V are sometimes added for the purpose of improving corrosion resistance. Regarding the Ferrite 1-based stainless steel 1/S containing T1, Nb, , v amount in this range gH, Okaki (1
) for Hv hardness using the same method used to find the formula.
The results of calculating the coefficients of the elements are +112, +172, +74
It was calculated that it had a large hardening effect. However, when Ti, Nb, and V are added in an amount of 0.2% or less, the addition of Ti, Nb, and V in an amount of approximately 3% or less (atomic percent) and Nz substantially converts the solid solution nitrogen into nitrides, resulting in a solid solution hardening effect. It has been found that solid solution Ti, Nb, and V can be kept at negligible levels without exhibiting a significant hardening effect.

まｒ、：　Ｔ　ｉの添加は、溶製後の連続鋳造に際して
タンディツシュや浸６Ｒ管のノズル詰りを発生させ、ま
た地疵の発生頻度を高めるなどの問題点があるが、本発
明ではＮを００３％以下に限定しているのでＴｉを０２
０％以下添加することにより、かかろ障害も防止できる
のでその上限を０２０％としｔこ。The addition of Ti causes problems such as clogging of the nozzle of the tandish and immersion 6R pipe during continuous casting after melting, and increases the frequency of ground defects. However, in the present invention, the addition of N Since Ti is limited to 0.03% or less, Ti is
Adding 0% or less can prevent damage, so the upper limit is set at 0.20%.

またＴｉ、Ｎｂ、■添加の上記効果１ｉｉ！！Ｉ量の７
・弧加量ても相応の効果が期待てきるが、実質的な効果
を得るｔ：めには少くとも０．００５％を要するので、
それぞれ０００５〜０．２０％の範囲に限定１７た。Also, the above effects 1ii of adding Ti, Nb, and ■! ! I quantity 7
・Although arc addition can be expected to have a corresponding effect, at least 0.005% is required to obtain a substantial effect.
Each was limited to a range of 0.0005% to 0.20%17.

フェライト系ステンレス鋼の主要元素含有量と硬さの関
係は前記（１）式で定板的に表わされることを明らかに
したが、本発明ではＡ１．Ｔｉ　ＸＮｂ　。It has been clarified that the relationship between the main element content and hardness of ferritic stainless steel is expressed as a fixed plate by the above equation (1), but in the present invention, A1. TiXNb.

■を適当撤添加ずろことにより強力な固溶硬化作用を有
ｔ　７１　Ｎ　全固定し、ＡＩ、　Ｔｉ　’ｔ　Ｎｂ、
　Ｖ自身の固溶硬化も無視し得るレベルに保つことを可
能とした。この乙とにより＋１１式におけるＮの項およ
びＡＩ　ＸＴｉ　、　Ｎｂ、　Ｖの硬化作用を無視した
下記の硬さ指数ＨｖＮで実質的な硬さと成分の関係を表
示できることがわかった。By appropriately removing and removing ①, a strong solid solution hardening effect can be achieved.
This also made it possible to keep the solid solution hardening of V itself at a negligible level. It has been found that the relationship between the substantial hardness and the components can be expressed by the following hardness index HvN, which ignores the N term in Equation +11 and the hardening effects of AI XTi, Nb, and V.

硬さ指数ＨｖＮ＝７３．３−１２．３（ＸＣｒｌ＋２２
．７（ＸＳｉ１＋０．８　（ＸＭｎ）＋３６１　（ｚｐ
）　−５５，１ＫＳＩ＋　２．９　（ＸＣｒ）＋　２．
６　（ｚＮｉ）＋　９．８　（ＸＣｕ）＋　５１　（Ｘ
Ｍｏ）−４２） 本発明においては、既存の従来材と比較し、貨幣、メダ
ル、ゲーム用コインもしくは鍵等の圧印加工時の圧印圧
力が大幅に軽減できる値として（２）式の硬さ指数Ｈｖ
Ｎを１４０以下にすることが望ましい。Hardness index HvN=73.3-12.3 (XCrl+22
．． 7(XSi1+0.8 (XMn)+361 (zp
) -55,1KSI+ 2.9 (XCr)+ 2.
6 (zNi) + 9.8 (XCu) + 51 (X
Mo)-42) In the present invention, the hardness index of formula (2) is used as a value that can significantly reduce coining pressure during coining processing of coins, medals, game coins, keys, etc. compared to existing conventional materials. Hv
It is desirable that N be 140 or less.

上記各成分の限定要件を満し、残部はＦｅおよび不可避
的不純物より成り、更に好適には上記硬さ指数を満たす
フェライト系ステンレス鋼は、その最終の冷延焼純板の
Ｈｖ硬さで１４０以下を確保することが可能であり、従
来よりも著（７く軟質のフェライト系ステンレス鋼を得
ることができた。A ferritic stainless steel that satisfies the above-mentioned limiting requirements for each component, with the remainder consisting of Fe and unavoidable impurities, and more preferably satisfies the above-mentioned hardness index, has an Hv hardness of 140 or less in the final cold-rolled and sintered sheet. It was possible to obtain a ferritic stainless steel that was significantly softer than before.

本発明では最終の冷延後の焼鈍条件は特に規制（７ない
が、ＡＩのみの添加材の場合、焼Ｍ　＞７４度が約９０
０℃以上になるとＡｌＮの再固溶が生じ固溶窒素が増し
硬度上昇を生起させるため９００℃未満の焼鈍が望まし
い。In the present invention, the annealing conditions after the final cold rolling are not particularly regulated (7), but in the case of an additive material containing only AI, the annealing M > 74 degrees is about 90 degrees.
When the temperature exceeds 0°C, re-solid solution of AlN occurs, and the amount of solid solute nitrogen increases, causing an increase in hardness. Therefore, annealing at a temperature of less than 900°C is desirable.

〔実施例〕〔Example〕

第１表に示す如きＡ−３の１９種の本発明によるフェラ
イト系ステンレス鋼および比較鋼として５ＵＳ４３０お
よびイタリアコイン用フェライト系ステンレス鋼と同質
ステンレス鋼および低炭素、低窒素であるが、Ｔ１また
はＮｂがそれぞれ０．３６％、０．５０％と本発明によ
る限定量よりも過度にＴｉＸＮｂを含む７エライト系ス
テンレス鋼の比較鋼Ｔ、Ｕをいずれも同様に高周波真空
溶解炉で溶製し、それぞれ３０ｋｇの鋼塊とした。As shown in Table 1, 19 kinds of ferritic stainless steels of A-3 according to the present invention and comparative steels include 5US430 and stainless steels similar to ferritic stainless steels for Italian coins, and low carbon and low nitrogen, but T1 or Nb Comparative steels T and U, which are 7-elite stainless steels containing TiXNb in an amount of 0.36% and 0.50%, respectively, exceeding the limited amount according to the present invention, were similarly melted in a high-frequency vacuum melting furnace. It was made into a 30 kg steel ingot.

これらの鋼塊をいずれも同一条件で１２５０℃に加熱後
熱間圧延を行い３鴎厚の熱延板とした。All of these steel ingots were heated to 1250° C. under the same conditions and then hot-rolled to obtain hot-rolled sheets with a thickness of 3 mm.

その際の熱間圧延仕上温度は８３０℃であったっこの熱
延板を公知の方法により焼なまし、冷間圧延、仕上焼な
ましを行い１．２ｍｍ厚の冷延焼ｔｉｅ　５％板を得た
。The hot-rolled finish temperature at that time was 830°C. This hot-rolled plate was annealed by a known method, cold-rolled, and finished annealed to obtain a cold-rolled tie 5% plate with a thickness of 1.2 mm. Ta.

−ａにコイン材としては１２〜２．７ｍｍ厚の材料が使
用されるが、上記各工程処理を経ても本発明鋼および比
較鋼はいずれもリジングに伴う表面性状の劣化は見られ
ず、その後のテス）・コインの試作に当ってもなんらの
１−ラブルが発生しなかった。A material with a thickness of 12 to 2.7 mm is used as the coin material for -a, but even after the above-mentioned processes, neither the inventive steel nor the comparative steel showed any deterioration in surface quality due to ridging. No 1-ruble occurred during the prototype production of the Tess) coin.

従ってリジングに関して特別な条件で工程処理する必要
がないことが判明しｔ：。Therefore, it was found that there was no need to process the process under special conditions regarding ridging.

これらの各供試材についてＨｖ硬さ、降伏応力、引張強
さおよび伸びの機械的性質を測定し、第１表に同時に示
した。第１表より明らかな如く、本発明鋼はＨｖ硬さは
１０３〜１３８の範囲であり、比較鋼５ｔＪＳ　４３０
の１５７、イタリアコイン用ステンレス鋼の１６３より
も著しく軟質となってし１ろことがわかる。比較鋼の硬
さが（２）式による硬さ指数と大きく異なる理由はこれ
らの鋼では固溶Ｎおよび固溶Ｔｉ、Ｎｂが硬さに寄与し
ているためと考えられる。The mechanical properties of Hv hardness, yield stress, tensile strength, and elongation were measured for each of these test materials, and are also shown in Table 1. As is clear from Table 1, the Hv hardness of the steel of the present invention is in the range of 103 to 138, and that of the comparative steel 5tJS 430.
It can be seen that 157 is significantly softer than 163, the stainless steel used for Italian coins. The reason why the hardness of the comparative steels is significantly different from the hardness index determined by equation (2) is thought to be that in these steels, solid solution N, solid solution Ti, and Nb contribute to the hardness.

次に本発明のうちＣｒ含有３１１２．５％クラスおよび
１７５％クラスの異なるＣｒレベルの代表鋼として供試
材Ｂ、、ＪおよびＦ、Ｌを取り挙げて、従来からコイン
用素材として広く使用されている白銅、黄銅、アルミニ
ウム、ニッケルを比較材として耐食性、耐摩耗性、コイ
ニング性の比較試験を行った。耐食性は上９己の人工汗
中の孔食電位によって評価した。なお、本発明鋼Ｆおよ
び比較材臼銅の耐食試験の人工汗溶液中のアノード分極
曲線をそれぞれ第４図、第５図に示しｔ：。Next, we will take up sample materials B, J, F, and L as representative steels with different Cr levels in the 3112.5% Cr content class and the 175% Cr class of the present invention. Comparative tests were conducted on corrosion resistance, abrasion resistance, and coining properties using comparative materials such as cupronickel, brass, aluminum, and nickel. Corrosion resistance was evaluated by pitting corrosion potential in artificial sweat. In addition, the anode polarization curves in the artificial sweat solution of the corrosion resistance test of the steel F of the present invention and the comparative mortar copper are shown in FIGS. 4 and 5, respectively.

また、耐摩耗試験は大越式耐摩耗試験機を用い、荷重３
．２ｋｇ、摩耗距ｇｉ６６．６　ｍ、　摩耗速度０、５
１　ｍ／ｓｅ　ｃの条件で比摩耗量を測定した。In addition, the wear resistance test was carried out using an Okoshi type wear resistance tester, and a load of 3
．． 2 kg, wear distance gi 66.6 m, wear rate 0, 5
The specific wear amount was measured under the condition of 1 m/sec.

更にコイニング時の圧印力測定のために、本発明による
供試材Ｂ、Ｆ、Ｊ、Ｉ−および各比較材から２５ｍｍφ
のブランクを打抜き、これを圧線による耳付は後、ダイ
ス材質、ＩＩＳ　　Ｇ４４０４による５ＫＤ１１を使用
し圧印深さ２５０μｍの条件でコインを作成し、周辺の
ぼりの発生、模様の彫りの状況から最適圧印力を測定し
た。Furthermore, in order to measure the coining force during coining, 25 mm
After punching out the blank and attaching the ears using a pressure wire, a coin was made using a die material of 5KD11 according to IIS G4404 with a coining depth of 250 μm, and the optimal coining was determined based on the occurrence of peripheral banners and the engraving of the pattern. The force was measured.

なお、比較材として使用した白銅は７５％Ｃｕ−２５％
Ｎｉ合金であり、黄銅は７０％Ｃｕ　−３０％Ｚｎ合金
である。これら本発明鋼および比較材による耐食性、耐
摩耗性、最適圧印力によるコイニング性の比較試験Ｃよ
第２表に示すとおりである。The cupronickel used as a comparative material was 75% Cu-25%.
The brass is a 70% Cu-30% Zn alloy. Comparative test C of the corrosion resistance, abrasion resistance, and coining property using the optimum coining force of the steels of the present invention and comparative materials is as shown in Table 2.

第　　２　　表 、第２表より明らかな如く、本発明によるフェライト系
ステンレス鋼供試材Ｂ、ＦＸＪ、Ｌは他の比較材に比し
次の如きすぐれた特性を有している。As is clear from Tables 2 and 2, the ferritic stainless steel specimens B, FXJ, and L according to the present invention have the following superior properties compared to other comparative materials.

すなわち、 （イ）耐食性に関しては、本発明鋼は他の非鉄コイン材
料の白銅、黄銅、アルミニウム、ニッケルよりはるかに
すぐれ、５ＵＳ４３０、イタリアコイン用ステンレス鍔
とほぼ同等である。That is, (a) In terms of corrosion resistance, the steel of the present invention is far superior to other nonferrous coin materials such as cupronickel, brass, aluminum, and nickel, and is almost equivalent to 5US430 and stainless steel tsuba for Italian coins.

（ロ）耐摩耗性についても、本発明鋼は非鉄コイン材料
の比較材およびイタリアコイン用ステンレユ鋼よりすぐ
れ、５Ｕｓ４３ｏとほぼ同等である。(b) Regarding wear resistance, the steel of the present invention is superior to comparative non-ferrous coin materials and stainless steel for Italian coins, and is almost equivalent to 5Us43o.

（ハ）コイン材等の冷間プレスによろ圧印加工に最も重
要な特性である最適圧印力に関しては、本発明鋼は耳付
は後焼鈍を施さなくとも３０３４３０、イタリアコイン
用ステンしス鋼等の他のフェライト系ステンレス鋼に比
し著しく低い値を示し、他の非鉄コイン材料の比較材に
比しても黄銅、ニッケルよりすぐれ、白銅、アルミニウ
ムの域に迫る低値にて、コイン用等の冷間てプレス成形
されろ用途に最適の材料であることを示している。これ
は第１表にて明らかにした本発明鋼の極軟質に、よる結
果である。(c) Regarding the optimum coining force, which is the most important characteristic for cold press filter coining of coin materials, etc., the steel of the present invention is 303430 without post-annealing, stainless steel for Italian coins, etc. It exhibits a significantly lower value than other ferritic stainless steels, and when compared to other comparative non-ferrous coin materials, it is superior to brass and nickel, and close to the level of cupronickel and aluminum, making it suitable for coins, etc. This indicates that the material is ideal for cold press forming applications. This result is due to the extremely soft nature of the steel of the present invention as shown in Table 1.

〔発明の効果〕〔Effect of the invention〕

本発明によるフェライト系ステンレス鋼は適正な成分組
成を有し、特に極軟質および高耐食性とする本発明の目
的からＳｉ　、　Ｐ、　Ｃｕ、　Ｍｏ、　Ｎを低減する
と同時に、ｋｌをｏ、ｏｏｓ〜０．２０％とし、更に０
００５〜０２０％のＴｉ、Ｎｂ、Ｖを１種以上添加する
ことにより、ＮをＡｌＮまたはＴｉＮ、ＮｂＮ、ＶＮと
して固定し、その固溶硬化作用を無害化し、併せてＳｉ
不足による脱酸作用の不足を補う組成としたので次の如
き効果を挙げることができた。The ferritic stainless steel according to the present invention has an appropriate composition, and in particular, for the purpose of the present invention to make it extremely soft and highly corrosion resistant, Si, P, Cu, Mo, and N are reduced, and at the same time kl is reduced to o, oos ~ 0. .20% and then 0
By adding one or more of 005 to 020% of Ti, Nb, and V, N is fixed as AlN, TiN, NbN, and VN, its solid solution hardening effect is rendered harmless, and Si
Since the composition was designed to compensate for the lack of deoxidizing effect due to the deficiency, the following effects could be achieved.

（イ）硬さは極めて軟質であって、ＨｖｌＯＯ〜１４０
を示し、その結果最適圧印力は極めて低い。(a) Hardness is extremely soft, HvlOO~140
, and as a result the optimum coining force is extremely low.

（ロ）耐食性、耐摩耗性についても、他の非鉄コイン材
料より著しくすぐれている。(b) Corrosion resistance and abrasion resistance are also significantly superior to other non-ferrous coin materials.

（ハ）／？ｉ延祠の表面性状がすぐれている。(ha)/? i The surface quality of the engraving is excellent.

（ニ）製造コストが割安である。(d) Manufacturing costs are low.

（ホ）コイン材としてもイタリアコイン用フェライト系
ステンレス鋼よりすべての点ですぐれた最適材料である
。(e) As a coin material, it is an optimal material superior to ferritic stainless steel for Italian coins in all respects.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図はフェライト系ステンレス鋼を使用するイタリア
１００リラ貨幣の表面および裏面形状の測定図、第２図
は７５％Ｃｕ−２５％Ｎｉの白銅を使用する日本の１０
０円貨幣の表面および裏面形状の測定図、第３図は人工
汗溶液中の孔食電位と炭素含有量との関係を示す線図、
第４図は本発明鋼の実施例である供試材Ｆの耐食試験の
人工汗溶液中のアノード分極曲線図、第５図は比較材白
銅の第４図と同様の人工汗溶液中のアノード分極曲線図
である。Figure 1 is a measurement diagram of the front and back shapes of an Italian 100 lira coin made of ferritic stainless steel, and Figure 2 is a measurement diagram of the Japanese 100 lira coin made of 75% Cu-25% Ni cupronickel.
A measurement diagram of the front and back shapes of a 0 yen coin. Figure 3 is a diagram showing the relationship between pitting potential and carbon content in an artificial sweat solution.
Figure 4 is an anode polarization curve diagram in an artificial sweat solution for the corrosion resistance test of specimen F, which is an example of the steel of the present invention, and Figure 5 is an anode polarization curve in an artificial sweat solution similar to Figure 4 for comparative material cupronickel. It is a polarization curve diagram.

Claims (2)

【特許請求の範囲】[Claims] （１）重量比にてＣ：０．０３％未満 Ｓｉ：０．３０％以下 Ｍｎ：１．５％以下 Ｐ：０．０４％以下 Ｓ：０．１５％以下 Ｎｉ：１．０％以下 Ｃｕ：０．５０％以下 Ｍｏ：０．６０％以下 Ｃｒ：１１．５〜２０％ Ｎ：０．０３％以下 Ａｌ：０．００５〜０．２０％ を含有し、残部はＦｅおよび不可避的不純物より成り、
硬度がビッカース硬度スケールで１４０以下であり圧印
加工性に優れたことを特徴とする極軟質フェライト系ス
テンレス鋼。(1) Weight ratio C: less than 0.03% Si: 0.30% or less Mn: 1.5% or less P: 0.04% or less S: 0.15% or less Ni: 1.0% or less Cu : 0.50% or less Mo: 0.60% or less Cr: 11.5-20% N: 0.03% or less Al: 0.005-0.20%, the remainder being Fe and unavoidable impurities. Becomes,
An extremely soft ferritic stainless steel characterized by a hardness of 140 or less on the Vickers hardness scale and excellent coining workability. （２）重量比にてＣ：０．０３％未満 Ｓｉ：０．３０％以下 Ｍｎ：１．５％以下 Ｐ：０．０４％以下 Ｓ：０．１５％以下 Ｎｉ：１．０％以下 Ｃｕ：０．５０％以下 Ｍｏ：０．６０％以下 Ｃｒ：１１．５〜２０％ Ｎ：０．０３％以下 Ａｌ：０．００５〜０．２０％ を含有し、更にＴｉ：０．００５〜０．２０％、Ｎｂ：
０．００５〜０．２０％、Ｖ：０．００５〜０．２０％
の中から選ばれた１種以上を含み残部はＦｅおよび不可
避的不純物より成り、硬度がビッカース硬度スケールで
１４０以下であり圧印加工性に優れたことを特徴とする
極軟質フェライト系ステンレス鋼。(2) Weight ratio C: less than 0.03% Si: 0.30% or less Mn: 1.5% or less P: 0.04% or less S: 0.15% or less Ni: 1.0% or less Cu : 0.50% or less Mo: 0.60% or less Cr: 11.5-20% N: 0.03% or less Al: 0.005-0.20%, and Ti: 0.005-0 .20%, Nb:
0.005-0.20%, V: 0.005-0.20%
An ultra-soft ferritic stainless steel characterized by containing one or more selected from the following, the remainder being Fe and unavoidable impurities, having a hardness of 140 or less on the Vickers hardness scale, and having excellent coining workability.