JP2000248339A - Austenitic free cutting stainless steel excellent in workability and corrosion resistance - Google Patents
Austenitic free cutting stainless steel excellent in workability and corrosion resistanceInfo
- Publication number
- JP2000248339A JP2000248339A JP4958199A JP4958199A JP2000248339A JP 2000248339 A JP2000248339 A JP 2000248339A JP 4958199 A JP4958199 A JP 4958199A JP 4958199 A JP4958199 A JP 4958199A JP 2000248339 A JP2000248339 A JP 2000248339A
- Authority
- JP
- Japan
- Prior art keywords
- weight
- stainless steel
- corrosion resistance
- machinability
- workability
- 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
- 238000005520 cutting process Methods 0.000 title claims abstract description 26
- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 26
- 230000007797 corrosion Effects 0.000 title claims abstract description 25
- 238000005260 corrosion Methods 0.000 title claims abstract description 25
- 239000010935 stainless steel Substances 0.000 title claims abstract description 23
- 230000001105 regulatory effect Effects 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 4
- 229910000963 austenitic stainless steel Inorganic materials 0.000 abstract description 6
- 229910052748 manganese Inorganic materials 0.000 abstract description 6
- 229910052804 chromium Inorganic materials 0.000 abstract description 5
- 229910052802 copper Inorganic materials 0.000 abstract description 5
- 229910052759 nickel Inorganic materials 0.000 abstract description 5
- 230000002542 deteriorative effect Effects 0.000 abstract description 3
- 229910000831 Steel Inorganic materials 0.000 description 22
- 239000010959 steel Substances 0.000 description 22
- 239000000463 material Substances 0.000 description 11
- 229910045601 alloy Inorganic materials 0.000 description 7
- 239000000956 alloy Substances 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 6
- 239000002436 steel type Substances 0.000 description 6
- 229910001566 austenite Inorganic materials 0.000 description 5
- 230000002596 correlated effect Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 4
- 238000005554 pickling Methods 0.000 description 4
- 238000002791 soaking Methods 0.000 description 4
- 230000002411 adverse Effects 0.000 description 3
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 238000000137 annealing Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 229910000734 martensite Inorganic materials 0.000 description 2
- 238000004080 punching Methods 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 230000037303 wrinkles Effects 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 229910001315 Tool steel Inorganic materials 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 230000000875 corresponding effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、加工性，耐食性が良好
で、特に加工後の切削性に優れたオーステナイト系ステ
ンレス鋼に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an austenitic stainless steel having good workability and corrosion resistance, and particularly excellent in machinability after working.
【０００２】[0002]
【従来の技術】各種フランジの口金，止め金具のナット
等の用途に使用される素材には、目標形状に加工した後
でねじ切り加工されることから、良好な切削性が要求さ
れる。また、普通鋼を素材として加工，表面処理を施し
て使用されてきた部品等でも、耐食性，外観等を重視し
てステンレス鋼が使用されるようになってきている。ス
テンレス鋼は、一般的にいって普通鋼に比較すると切削
性が劣る。そこで、切削工程が入る用途向けでは、Ｓ含
有量を高く設定して鋼中に介在物を分散させること，Ｐ
ｂ等の快削性付与元素を添加して鋼中に第２相を分散さ
せること等によりステンレス鋼の切削性を改善してい
る。オーステナイト系ステンレス鋼の切削性を改善した
鋼種としては、ＳＵＳ３０３，ＳＵＳ３０３Ｓｅ等がＪ
ＩＳ Ｇ４３０３に挙げられている。2. Description of the Related Art Materials used for applications such as bases for various flanges, nuts for fasteners, and the like are required to have good cutting properties because they are formed into a target shape and then threaded. In addition, even for parts and the like which have been processed and surface-treated using ordinary steel as a material, stainless steel has come to be used with emphasis on corrosion resistance, appearance, and the like. Generally speaking, stainless steel is inferior in machinability as compared with ordinary steel. Therefore, for applications that involve a cutting process, it is necessary to set a high S content to disperse inclusions in the steel.
The machinability of the stainless steel is improved by adding a free-machining element such as b to disperse the second phase in the steel. SUS303, SUS303Se, etc., which have improved machinability of austenitic stainless steel, are J.
IS G4303.
【０００３】[0003]
【発明が解決しようとする課題】切削性を改善した従来
のステンレス鋼は、介在物等の第２相が鋼中に分散して
いるため、ステンレス鋼本来の特徴である耐食性が低下
し易い。第２相は、加工時に割れ発生の起点となり、ス
テンレス鋼の加工性を低下させる原因にもなる。低い加
工性のため、快削ステンレス鋼から複雑形状の製品を製
造するとき、プレス成形の採用が困難であり、棒鋼，鍛
造鋼等のバルク材を削り出す切削加工が余儀なくされ
る。しかし、切削加工は、プレス成形に比較すると長時
間を要し、製品となる材料の歩留も低い。他方、ＳＵＳ
３０４に代表される成形性の良好なオーステナイト系ス
テンレス鋼は、プレス成形が可能であるが、後続するネ
ジきり加工で切削工具が著しく摩耗し、加工コストの上
昇を招く。In a conventional stainless steel having improved machinability, the second phase such as inclusions is dispersed in the steel, so that the corrosion resistance, which is a characteristic feature of the stainless steel, tends to decrease. The second phase is a starting point of crack generation during processing, and also causes deterioration of workability of stainless steel. Due to low workability, it is difficult to employ press forming when manufacturing a product having a complicated shape from free-cutting stainless steel, and cutting work for cutting bulk materials such as bar steel and forged steel is inevitable. However, cutting requires a longer time than press forming, and the yield of a material to be a product is low. On the other hand, SUS
Austenitic stainless steel having good formability, such as 304, can be press-formed, but the cutting tool is significantly worn by subsequent threading, resulting in an increase in processing cost.
【０００４】[0004]
【課題を解決するための手段】本発明は、このような問
題を解消すべく案出されたものであり、加工性，切削性
の改善に有効なＮｉ，Ｃｒ，Ｍｎ，Ｃｕの含有量を単独
及び相関的に調整することにより、耐食性や加工性を劣
化させることなく、切削性が改善されたオーステナイト
系ステンレス鋼を提供することを目的とする。本発明の
オーステナイト系快削ステンレス鋼は、その目的を達成
するため、Ｃ：０．０４０重量％以下，Ｎ：０．０３５
重量％以下，Ｓｉ：１．０重量％以下，Ｍｎ：５重量％
以下，Ｃｒ：１５〜２０重量％，Ｎｉ：５〜１０重量
％，Ｃｕ：１〜５重量％，Ｓ：０．００６重量％以下を
含み、残部が実質的にＦｅの組成をもち、Ｃ＋Ｎ／２≦
０．０３０重量％及びＮｉ＋０．５×Ｃｒ＋Ｍｎ＋Ｃｕ
＞１９重量％を満足していることを特徴とする。Ｓ含有
量は、好ましくは０．００３重量％以下に規制する。DISCLOSURE OF THE INVENTION The present invention has been devised in order to solve such a problem, and it is intended to reduce the contents of Ni, Cr, Mn, and Cu effective for improving workability and machinability. It is an object of the present invention to provide an austenitic stainless steel having improved machinability without deteriorating corrosion resistance and workability by adjusting independently and in a correlated manner. In order to achieve the object, the austenitic free-cutting stainless steel of the present invention has a C content of 0.040% by weight or less and a N content of 0.035%.
Wt% or less, Si: 1.0 wt% or less, Mn: 5 wt%
In the following, Cr: 15 to 20% by weight, Ni: 5 to 10% by weight, Cu: 1 to 5% by weight, S: 0.006% by weight or less, and the balance substantially has a composition of Fe, and C + N / 2 ≦
0.030% by weight and Ni + 0.5 × Cr + Mn + Cu
> 19% by weight. The S content is preferably regulated to 0.003% by weight or less.
【０００５】[0005]
【作用】ステンレス鋼の切削性はＳ含有量を高めに設定
すること，快削性付与元素を添加すること等により改善
されるが、何れも耐食性低下，加工性低下等の悪影響が
現れる。そこで、本発明者等は、ステンレス鋼の耐食
性，加工性等を改善するために積極的に添加されている
合金成分の中から、切削性に有効な合金成分を選択し、
合金元素の含有量が切削性に及ぼす影響を調査した。そ
の結果、Ｎｉ，Ｃｒ，Ｍｎ，Ｃｕの含有量を単独で且つ
相関的に調整すると共に、Ｃ＋Ｎ／２量を規制すると
き、耐食性や加工性を劣化させることなく、切削性が改
善できることを見出した。The machinability of stainless steel can be improved by setting a high S content or adding an element that imparts free-cutting properties, but all have adverse effects such as reduced corrosion resistance and reduced workability. Therefore, the present inventors have selected alloy components that are effective for machinability from among alloy components that are positively added to improve corrosion resistance, workability, etc. of stainless steel,
The effect of alloying element content on machinability was investigated. As a result, it has been found that when the contents of Ni, Cr, Mn, and Cu are adjusted independently and in a correlated manner, and when the amount of C + N / 2 is regulated, the machinability can be improved without deteriorating the corrosion resistance and workability. Was.
【０００６】以下、本発明ステンレス鋼に含まれる合金
成分，含有量等を説明する。 Ｃ：０．０４０重量％以下 Ｎ：０．０３５重量％以下 Ｃ＋Ｎ／２≦０．０３０重量％ 多量に含まれると、固溶強化によりオーステナイト相を
硬質化させる。また、加工誘起マルテンサイト相も硬質
化し、切削性を低下させる。そこで、本発明において
は、Ｃ含有量及びＮ含有量の上限をそれぞれ０．０４０
重量％，０．０３５重量％に規制すると共に、Ｃ＋Ｎ／
２を０．０３０重量％以下に規制した。Ｃ＋Ｎ／２が
０．０３０重量％を超えると、オーステナイト相自体の
硬質化に加え、加工誘起マルテンサイト相も硬質化する
ため、切削性が低下する。 Ｓｉ：１．０重量％以下 溶製時に脱酸剤として添加される成分であるが、１．０
重量％を超える量のＳｉが含まれると固溶強化によって
オーステナイト相が硬質化し、切削性が低下する。Hereinafter, alloy components, contents, and the like contained in the stainless steel of the present invention will be described. C: 0.040% by weight or less N: 0.035% by weight or less C + N / 2 ≦ 0.030% by weight When contained in a large amount, the austenite phase is hardened by solid solution strengthening. Further, the work-induced martensite phase is also hardened, and the machinability is reduced. Therefore, in the present invention, the upper limits of the C content and the N content are each set to 0.040.
% And 0.035% by weight, and C + N /
2 was regulated to 0.030% by weight or less. When C + N / 2 exceeds 0.030% by weight, not only the austenite phase itself is hardened, but also the work-induced martensite phase is hardened, resulting in reduced machinability. Si: 1.0% by weight or less Si is a component added as a deoxidizing agent during melting.
If the amount of Si exceeds the weight percent, the austenite phase is hardened by solid solution strengthening, and the machinability decreases.
【０００７】Ｍｎ：５重量％以下 Ｍｎ含有量が多くなるに従ってオーステナイト相が安定
化し、切削性も向上する。しかし、５重量％を超える量
のＭｎが含まれても、増量に見合った切削性に改善はみ
られず、却って介在物の増加に起因して耐食性や加工性
が低下する傾向が示される。 Ｃｒ：１５〜２０重量％ 耐食性の向上に有効な合金成分であり、１５重量％以上
の含有量を必要とする。しかし、過剰量のＣｒが含まれ
ると成形性，切削性が低下するため、Ｃｒ含有量の上限
を２０重量％に設定した。Mn: 5% by weight or less As the Mn content increases, the austenite phase is stabilized and the machinability is improved. However, even if Mn is contained in an amount exceeding 5% by weight, the machinability corresponding to the increase is not improved, and the corrosion resistance and the workability tend to be reduced due to the increase of inclusions. Cr: 15 to 20% by weight An alloy component effective for improving corrosion resistance, and requires a content of 15% by weight or more. However, if an excessive amount of Cr is contained, formability and machinability deteriorate, so the upper limit of the Cr content was set to 20% by weight.
【０００８】Ｎｉ：５〜１０重量％ オーステナイト系ステンレス鋼では不可欠な合金成分で
あり、オーステナイト相を確保するために５重量％以上
のＮｉが必要である。成形性及び切削性は、Ｎｉ含有量
の増量に応じて向上する。しかし、高価な元素であり、
１０重量％以下のＮｉで成形性及び切削性の向上が達成
されることから、Ｎｉ含有量の上限を１０重量％に設定
した。 Ｃｕ：１〜５重量％ 成形性，切削性の改善に有効な合金成分であり、１重量
％以上でＣｕの添加効果が顕著になる。しかし、過剰量
のＣｕが含まれると熱間加工性が劣化するので、Ｃｕ含
有量の上限を５重量％に設定した。Ni: 5 to 10% by weight Ni is an indispensable alloy component in austenitic stainless steel, and 5% by weight or more of Ni is necessary to secure an austenitic phase. Formability and machinability improve with increasing Ni content. However, it is an expensive element,
Since the moldability and machinability are improved with Ni of 10% by weight or less, the upper limit of the Ni content is set to 10% by weight. Cu: 1 to 5% by weight An alloy component effective for improving formability and machinability. When the content is 1% by weight or more, the effect of adding Cu becomes remarkable. However, the hot workability deteriorates when an excessive amount of Cu is contained, so the upper limit of the Cu content was set to 5% by weight.
【０００９】Ｓ：０．００６重量％以下 Ｓ含有量の増加に応じて切削性が向上するが、ステンレ
ス鋼に最も必要とされる耐食性に悪影響を及ぼすため、
Ｓ含有量の上限を０．００６重量％に設定した。耐食性
に加え、加工性、特に穴拡げ性を改善するためには、Ｓ
含有量を０．００３重量％以下に規制して加工性低下の
原因となる介在物を減少させることが好ましい。 Ｎｉ＋０．５×Ｃｒ＋Ｍｎ＋Ｃｕ＞１９重量％ Ｎｉ，Ｃｒ，Ｍｎ，Ｃｕは、何れも成形性及び切削性の
向上に有効な成分である。本発明では、これら合金成分
の含有量を単独及び相関的に調整することにより成形性
及び切削性を改善しているので、耐食性に悪影響を与え
がちなＳ系介在物の分散やプレス成形性に悪影響を与え
がちな快削性付与元素の添加を必要としない。また、Ｘ
＝Ｎｉ＋０．５×Ｃｒ＋Ｍｎ＋Ｃｕ−１９重量％として
定義されるＸ値は、オーステナイト相の安定化を表わす
指標であり、Ｘ値を正に維持するとき、加工硬化、ひい
ては調質圧延後の硬質化が抑制される。その結果、後述
する実施例にもみられるように切削時の工具摩耗が抑制
され、切削性が改善される。S: 0.006% by weight or less The machinability improves with an increase in the S content, but adversely affects the corrosion resistance most required for stainless steel.
The upper limit of the S content was set to 0.006% by weight. In order to improve workability, especially hole expandability, in addition to corrosion resistance, S
It is preferable to control the content to 0.003% by weight or less to reduce inclusions that cause a reduction in workability. Ni + 0.5 × Cr + Mn + Cu> 19% by weight Ni, Cr, Mn, and Cu are all effective components for improving formability and machinability. In the present invention, since the formability and machinability are improved by adjusting the content of these alloy components singly and in a correlated manner, the dispersibility and press formability of S-based inclusions that tend to have a bad influence on corrosion resistance are improved. It does not require the addition of free-cutting elements that tend to have an adverse effect. Also, X
The X value defined as = Ni + 0.5 × Cr + Mn + Cu−19% by weight is an index indicating the stabilization of the austenite phase. When the X value is maintained at a positive value, work hardening and, consequently, hardening after temper rolling are reduced. Is suppressed. As a result, as seen in the examples described later, tool wear during cutting is suppressed, and machinability is improved.
【００１０】[0010]
【実施例１】表１に示す組成をもつ各種鋼を溶製し、鋼
塊を抽出温度１２３０℃で熱間圧延して板厚８ｍｍの熱
延鋼帯を製造した。熱延鋼帯に１１５０℃×均熱１分の
熱延板焼鈍を施した後、酸洗し、板厚４．５ｍｍに冷間
圧延した。更に、１０５０℃×均熱１分の仕上げ焼鈍及
び酸洗を施し、冷延焼鈍板を得た。Example 1 Various steels having the compositions shown in Table 1 were melted, and a steel ingot was hot-rolled at an extraction temperature of 1230 ° C. to produce a hot-rolled steel strip having a thickness of 8 mm. The hot-rolled steel strip was annealed at 1150 ° C. and soaked for 1 minute, then pickled, and cold-rolled to a thickness of 4.5 mm. Furthermore, finish annealing and pickling were performed at 1050 ° C. × soaking for 1 minute to obtain a cold-rolled annealed plate.
【００１１】 [0011]
【００１２】各冷延焼鈍板を更に冷間圧延し、板厚２．
７ｍｍの調質圧延板を作製した。調質圧延板から１００
ｍｍ×１００ｍｍの試験片を切り出し、切削性試験に供
した。切削性試験では、定盤上に試験片を固定し、幅５
ｍｍの合金工具鋼ＳＫＳ１１（ＪＩＳ Ｇ４４０３）製
のバイトを周囲に取り付けた円盤状の工具を回転速度３
００ｒｐｍ，切込み深さ０．０５ｍｍ／回，切削距離８
０ｍｍで幅方向に５ｍｍの順送りを繰り返しながら切削
した。そして、バイト摩耗量が０．１ｍｍを超えた時点
での切削回数により試験片の切削性を評価した。なお、
快削ステンレス鋼ＳＵＳ３０３を比較材に使用した。表
２の試験結果にみられるように、比較材ＳＵＳ３０３の
切削回数は２０１２回であった。Ｘ値が正の鋼種番号
１，２，７〜９では、切削回数が比較材ＳＵＳ３０３と
同等以上であり、良好な切削性を示した。しかし、Ｘ値
が正であっても、（Ｃ＋Ｎ／２）が０．０３０重量％を
超えると、鋼種番号５，６にみられるように切削回数が
ＳＵＳ３０３を下回り、切削性が低下した。このことか
ら、良好な切削性を得るためには、Ｘ＞０及び（Ｃ＋Ｎ
／２）≦０．０３０重量％の双方が必要であることが判
る。Each cold-rolled annealed sheet is further cold-rolled to a thickness of 2.
A tempered rolled plate of 7 mm was produced. 100 from temper rolled sheet
A test piece of 100 mm × 100 mm was cut out and subjected to a cutting test. In the machinability test, a test piece was fixed on
mm tool tool steel SKS11 (JIS G4403) with a disk-shaped tool attached around it.
00rpm, depth of cut 0.05mm / time, cutting distance 8
Cutting was performed while repeating the sequential feeding of 5 mm in the width direction at 0 mm. Then, the machinability of the test piece was evaluated based on the number of cuts when the bite wear amount exceeded 0.1 mm. In addition,
Free-cutting stainless steel SUS303 was used as a comparative material. As can be seen from the test results in Table 2, the number of cuts of the comparative material SUS303 was 2012. In the case of steel type numbers 1, 2, 7 to 9 having positive X values, the number of cuts was equal to or greater than that of the comparative material SUS303, indicating good cutability. However, even when the X value was positive, when (C + N / 2) exceeded 0.030% by weight, the number of cuts was less than SUS303 as seen in steel type numbers 5 and 6, and the machinability was reduced. From this, in order to obtain good machinability, X> 0 and (C + N
/2)≦0.030% by weight.
【００１３】 [0013]
【００１４】良好な切削性を示した鋼種番号１，２，７
〜９のステンレス鋼について、板厚４．５ｍｍの冷延焼
鈍板から１５０ｍｍ×１５０ｍｍの試験片を切り出し、
ＪＩＳ Ｚ２３７１に準拠した塩水噴霧試験に供した。
塩水噴霧試験では、３５℃の５％ＮａＣｌ溶液を試験片
表面に噴霧し、赤錆の発生を目視観察した。そして、赤
錆が観察されるまでの時間で耐食性を評価した。耐食性
試験では、ＳＵＳ３０３に加えて、めっき厚８μｍでク
ロメート処理皮膜０．５ｇ／ｍ2 を形成した電気亜鉛め
っき普通鋼板を比較材に使用した。表３の調査結果にみ
られるように、電気亜鉛めっき普通鋼板（比較材）が赤
錆発生に至る時間は２５０時間であった。Ｓ含有量を
０．００６重量％以下に低減した鋼種番号１，２，７の
ステンレス鋼では、赤錆発生までの時間が電気亜鉛めっ
き普通鋼板より長く、高い耐食性が示された。Steel type numbers 1, 2, 7 showing good machinability
For stainless steels Nos. To 9, a test piece of 150 mm × 150 mm was cut out from a cold-rolled annealed plate having a thickness of 4.5 mm,
It was subjected to a salt spray test according to JIS Z2371.
In the salt spray test, a 5% NaCl solution at 35 ° C. was sprayed on the test piece surface, and the occurrence of red rust was visually observed. The corrosion resistance was evaluated by the time until red rust was observed. In the corrosion resistance test, in addition to SUS303, an electrogalvanized ordinary steel sheet having a plating thickness of 8 μm and a chromate treatment film of 0.5 g / m 2 was used as a comparative material. As can be seen from the inspection results in Table 3, the time required for the electrogalvanized ordinary steel sheet (comparative material) to generate red rust was 250 hours. In the stainless steels of steel types 1, 2 and 7 in which the S content was reduced to 0.006% by weight or less, the time until the occurrence of red rust was longer than that of the electrogalvanized ordinary steel sheet, and high corrosion resistance was exhibited.
【００１５】 [0015]
【００１６】切削性，耐食性共に良好であった試験番号
１，２，７のステンレス鋼について、板厚４．５ｍｍの
冷延焼鈍板を板厚１．０ｍｍに冷間圧延した後、１０５
０℃で１分間焼鈍し、酸洗した。酸洗後の冷延焼鈍板か
ら９０ｍｍ×９０ｍｍの試験片を切り出し、穴拡げ試験
に供した。穴拡げ試験では、ポンチ径１０ｍｍ，ダイス
径１０．２ｍｍの工具を用いて試験片の中心部に穴径ｄ
0 の打抜き穴を開けた後、打抜き穴の返りをポンチ側に
設定し、頂角３０度の円錐ポンチを用いて速度２０ｍｍ
／分，皺押え圧４トンで穴拡げ加工した。試験中、打抜
き穴周囲を目視観察し、割れが発生した時点での穴径ｄ
1 を測定した。そして、試験前後の穴径を比較し、λ＝
（ｄ1 −ｄ0 ）／ｄ0 として算出される穴拡げ比λによ
り穴拡げ性を評価した。表４の調査結果にみられるよう
に、比較材として使用した電気亜鉛めっき普通鋼鋼板の
穴拡げ比λは１．２０であった。これに対し、Ｓ含有量
を０．００３重量％以下に規制した鋼種番号２では、穴
拡げ比λが１．６０と大幅に高く、優れた穴拡げ性をも
っていた。Ｓ含有量が０．００４０重量％と若干高い試
験番号１のステンレス鋼でも、電気亜鉛めっき普通鋼鋼
板に匹敵する穴拡げ性を呈した。しかし、Ｓ添加により
切削性を改善したＳＵＳ３０３ステンレス鋼では、穴拡
げ開始直後に割れが発生し、穴拡げ加工に適さない材料
であった。With respect to the stainless steels of Test Nos. 1, 2 and 7, which had good cutting properties and corrosion resistance, a cold-rolled annealed sheet having a thickness of 4.5 mm was cold-rolled to a thickness of 1.0 mm.
Annealed at 0 ° C. for 1 minute and pickled. A test piece of 90 mm × 90 mm was cut out from the cold-rolled annealed plate after pickling, and subjected to a hole expansion test. In the hole expansion test, a hole diameter d was formed at the center of the test piece using a tool having a punch diameter of 10 mm and a die diameter of 10.2 mm.
After punching the punched hole of 0 , the return of the punched hole was set to the punch side, and the speed was set to 20 mm using a conical punch having a vertical angle of 30 degrees.
/ Min, the hole was expanded with a wrinkle press pressure of 4 tons. During the test, the area around the punched hole was visually observed, and the hole diameter d at the time when the crack was generated
1 was measured. Then, the hole diameters before and after the test are compared, and λ =
The hole expandability was evaluated by the hole expansion ratio λ calculated as (d 1 −d 0 ) / d 0 . As can be seen from the investigation results in Table 4, the hole expansion ratio λ of the electrogalvanized ordinary steel sheet used as the comparative material was 1.20. On the other hand, in steel type No. 2 in which the S content was regulated to 0.003% by weight or less, the hole expansion ratio λ was significantly high at 1.60, and had excellent hole expandability. Even the stainless steel of Test No. 1 having a slightly higher S content of 0.0040% by weight exhibited hole expandability comparable to that of an electrogalvanized ordinary steel sheet. However, in the case of SUS303 stainless steel in which machinability was improved by adding S, cracks occurred immediately after the start of hole expansion, and the material was not suitable for hole expansion.
【００１７】 [0017]
【００１８】[0018]
【実施例２】表５に示す組成をもつ各種鋼を溶製し、連
続鋳造法で得られた鋼塊を抽出温度１２３０℃で熱間圧
延し、板厚４ｍｍの熱延鋼帯を製造した。熱延鋼帯に１
１５０℃×均熱１分の熱延板焼鈍を施し、酸洗後に板厚
２ｍｍまで冷間圧延した。次いで、１０５０℃×均熱１
分で焼鈍し、酸洗後、更に板厚０．７ｍｍまで冷間圧延
した。冷延板に１０５０℃×均熱１分の焼鈍及び酸洗を
施し、冷延焼鈍板を得た。Example 2 Various steels having the compositions shown in Table 5 were melted, and a steel ingot obtained by continuous casting was hot-rolled at an extraction temperature of 1230 ° C. to produce a hot-rolled steel strip having a thickness of 4 mm. . 1 for hot rolled steel strip
The hot rolled sheet was annealed at 150 ° C. × 1 minute soaking, and cold-rolled to a sheet thickness of 2 mm after pickling. Next, 1050 ° C x soaking 1
And then cold-rolled to a sheet thickness of 0.7 mm. The cold rolled sheet was subjected to annealing at 1050 ° C. × soaking for 1 minute and pickling to obtain a cold rolled annealed sheet.
【００１９】 [0019]
【００２０】各冷延焼鈍板から外径８６ｍｍのブランク
を打ち抜き、ブランクの中心に径１０ｍｍの穴を打抜き
加工で形成した。次いで、径４０ｍｍのポンチ及び径４
２ｍｍのダイスを用い、速度１００ｍｍ／分，皺押え圧
力４トンでカップ状に深絞り成形し、カップ端部を切断
して図１に示す高さ５０ｍｍの成形品を作製した。得ら
れた各成形品の耐食性を実施例１と同様に調査すると共
に、カップ縁部を山高さ０．３０ｍｍでねじ切り加工
し、山高さが０．２５ｍｍ未満になる加工可能個数によ
り切削性を評価した。表６の調査結果にみられるよう
に、Ｘ値が正で（Ｃ＋Ｎ／２）量が０．０３０重量％以
下の鋼種番号１０，１１では、穴拡げ加工時に打抜き穴
端に割れが発生せず、電気亜鉛めっき普通鋼板を凌駕す
る深絞り加工性，穴拡げ性及び加工後の切削性を呈し
た。製品段階での耐食性は、電気亜鉛めっき普通鋼板に
比較して格段に優れていた。A blank having an outer diameter of 86 mm was punched from each cold-rolled annealed plate, and a hole having a diameter of 10 mm was formed at the center of the blank by punching. Next, a punch having a diameter of 40 mm and a diameter of 4 mm
Using a 2 mm die, a deep drawing was performed in a cup shape at a speed of 100 mm / minute and a wrinkle pressing pressure of 4 tons, and the end of the cup was cut to produce a molded product having a height of 50 mm shown in FIG. The corrosion resistance of each of the obtained molded products was investigated in the same manner as in Example 1, and the edge of the cup was thread-cut at a peak height of 0.30 mm, and the cutability was evaluated based on the number of possible cuts at which the peak height was less than 0.25 mm. did. As can be seen from the survey results in Table 6, in steel types Nos. 10 and 11 in which the X value is positive and the (C + N / 2) amount is 0.030% by weight or less, no crack is generated at the end of the punched hole during hole expanding. In addition, it exhibited deep drawing workability, hole expandability, and machinability after processing surpassed that of electrogalvanized ordinary steel sheets. The corrosion resistance at the product stage was much better than that of electrogalvanized plain steel.
【００２１】これに対し、Ｓｉ量が１．０重量％を超え
る試験番号１２，（Ｃ＋Ｎ／２）量が０．０３０重量％
を超える試験番号１３では、加工後の切削性が不良であ
った。Ｓ量が多い試験番号１４では、穴拡げ性に劣り、
穴拡げ加工時に割れが発生した。Ｘ値がマイナスで（Ｃ
＋Ｎ／２）量が高い試験番号１５，１６では、加工性に
劣り、時期割れに加えて穴端部に割れが発生した。Ｓ含
有量が多く（Ｃ＋Ｎ／２）量も０．０３０重量％を超え
る試験番号１７では、ねじ切り加工の際に所要高さが得
られなかった。Ｓにより切削性を改善した試験番号１８
では、プレス成形中にポンチ肩部、すなわちカップ底面
と壁部との境界で破断するα破断が発生した。On the other hand, Test No. 12, in which the Si content exceeds 1.0% by weight, and the (C + N / 2) amount is 0.030% by weight.
In Test No. 13 exceeding, the machinability after processing was poor. In Test No. 14 with a large amount of S, the hole expandability was poor,
Cracks occurred during hole expansion. X value is negative (C
In Test Nos. 15 and 16 in which the amount of (+ N / 2) was high, the workability was poor, and cracks occurred at the end portions of the holes in addition to the time cracks. In Test No. 17, in which the S content was large and the (C + N / 2) content also exceeded 0.030% by weight, the required height was not obtained during thread cutting. Test No. 18 with improved machinability by S
As a result, during press molding, an α-fracture occurred at the punch shoulder, that is, at the boundary between the cup bottom surface and the wall.
【００２２】 [0022]
【００２３】[0023]
【発明の効果】以上に説明したように、本発明のオース
テナイト系快削ステンレス鋼は、切削性の向上に有効な
Ｎｉ，Ｃｒ，Ｍｎ，Ｃｕの含有量を単独で且つ相関的に
規制すると共に、（Ｃ＋Ｎ／２）量を０．０３０重量％
以下に規制することにより、耐食性や加工性にとっては
有害な介在物や第２相を鋼中に分散させる必要なく、切
削性を改善している。そのため、従来の快削ステンレス
鋼では得られなかった優れた耐食性及び加工性をもつス
テンレス鋼となる。このようにして本発明のオーステナ
イト系快削ステンレス鋼は、削出しにより成形してきた
加工製品を安価なプレス成形品で代替できるため、耐食
性に優れた長所を活用して成形加工後にねじ切り加工が
必要な口金，ナット等を始めとして広範な分野で使用さ
れる。As described above, the austenitic free-cutting stainless steel of the present invention regulates the contents of Ni, Cr, Mn, and Cu effective for improving machinability independently and in a correlated manner. , (C + N / 2) amount of 0.030% by weight
By regulating below, it is not necessary to disperse inclusions and the second phase which are harmful to corrosion resistance and workability in the steel, thereby improving the machinability. Therefore, the stainless steel has excellent corrosion resistance and workability, which cannot be obtained with conventional free-cutting stainless steel. In this way, the austenitic free-cutting stainless steel of the present invention can replace the machined product formed by machining with an inexpensive press-formed product, and requires thread cutting after forming by utilizing the advantage of excellent corrosion resistance. It is used in a wide range of fields, such as in ferrules and nuts.
【図１】 実施例で深絞り加工及びねじ切り加工した成
形品の斜視図FIG. 1 is a perspective view of a molded product subjected to deep drawing and thread cutting in an embodiment.
Claims (2)
３５重量％以下，Ｓｉ：１．０重量％以下，Ｍｎ：５重
量％以下，Ｃｒ：１５〜２０重量％，Ｎｉ：５〜１０重
量％，Ｃｕ：１〜５重量％，Ｓ：０．００６重量％以下
を含み、残部が実質的にＦｅの組成をもち、Ｃ＋Ｎ／２
≦０．０３０重量％及びＮｉ＋０．５×Ｃｒ＋Ｍｎ＋Ｃ
ｕ＞１９重量％を満足している加工性及び耐食性に優れ
たオーステナイト系快削ステンレス鋼。C: 0.040% by weight or less, N: 0.0
35% by weight or less, Si: 1.0% by weight or less, Mn: 5% by weight or less, Cr: 15 to 20% by weight, Ni: 5 to 10% by weight, Cu: 1 to 5% by weight, S: 0.006 % By weight, with the balance being substantially Fe in composition, C + N / 2
≦ 0.030% by weight and Ni + 0.5 × Cr + Mn + C
Austenitic free-cutting stainless steel excellent in workability and corrosion resistance satisfying u> 19% by weight.
されている請求項１記載の加工性及び耐食性に優れたオ
ーステナイト系快削ステンレス鋼。2. The austenitic free-cutting stainless steel having excellent workability and corrosion resistance according to claim 1, wherein the S content is regulated to 0.003% by weight or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4958199A JP2000248339A (en) | 1999-02-26 | 1999-02-26 | Austenitic free cutting stainless steel excellent in workability and corrosion resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4958199A JP2000248339A (en) | 1999-02-26 | 1999-02-26 | Austenitic free cutting stainless steel excellent in workability and corrosion resistance |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2000248339A true JP2000248339A (en) | 2000-09-12 |
Family
ID=12835196
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4958199A Pending JP2000248339A (en) | 1999-02-26 | 1999-02-26 | Austenitic free cutting stainless steel excellent in workability and corrosion resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2000248339A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4758430B2 (en) * | 2004-09-07 | 2011-08-31 | オウトクンプ オサケイティオ ユルキネン | Steel shell for suction roll and method for producing steel product |
| JP2013163834A (en) * | 2012-02-09 | 2013-08-22 | Nisshin Steel Co Ltd | Exterior member of portable electronic device made of austenitic stainless steel and method for producing the same |
| EP3239341A4 (en) * | 2014-12-26 | 2018-10-31 | Posco | Austenitic stainless steel having excellent flexibility |
-
1999
- 1999-02-26 JP JP4958199A patent/JP2000248339A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4758430B2 (en) * | 2004-09-07 | 2011-08-31 | オウトクンプ オサケイティオ ユルキネン | Steel shell for suction roll and method for producing steel product |
| JP2013163834A (en) * | 2012-02-09 | 2013-08-22 | Nisshin Steel Co Ltd | Exterior member of portable electronic device made of austenitic stainless steel and method for producing the same |
| EP3239341A4 (en) * | 2014-12-26 | 2018-10-31 | Posco | Austenitic stainless steel having excellent flexibility |
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