JP2000190008A - Seamless steel pipe manufacturing tool and its manufacture - Google Patents
Seamless steel pipe manufacturing tool and its manufactureInfo
- Publication number
- JP2000190008A JP2000190008A JP36890998A JP36890998A JP2000190008A JP 2000190008 A JP2000190008 A JP 2000190008A JP 36890998 A JP36890998 A JP 36890998A JP 36890998 A JP36890998 A JP 36890998A JP 2000190008 A JP2000190008 A JP 2000190008A
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- Prior art keywords
- scale
- plug
- oxide scale
- thickness
- steel
- Prior art date
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、継目無鋼管を製造
する際の穿孔圧延機及び延伸圧延機に使用する継目無鋼
管製造用工具、特にプラグおよび該プラグの製造方法に
関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seamless steel pipe manufacturing tool used for a piercing rolling mill and an elongating rolling mill when manufacturing a seamless steel pipe, and more particularly to a plug and a method for manufacturing the plug.
【０００２】[0002]
【従来の技術】熱間圧延における継目無鋼管製造の代表
的な方法はプラグミル法及びマンドレルミル法である。
一般には製造外径７”（１７７．８ｍｍ）以上ではプラ
グミル法が、それより小さい外径の場合マンドレルミル
法が使われている。2. Description of the Related Art A typical method for producing a seamless steel pipe in hot rolling is a plug mill method and a mandrel mill method.
In general, a plug mill method is used for a production outer diameter of 7 ″ (177.8 mm) or more, and a mandrel mill method is used for a smaller outer diameter.
【０００３】図１に圧延工程を示した。なお、図１
（ａ）はマンドレルミル方式を示し、図１（ｂ）はプラ
グミル法を示す。図１に示すように、素材１は加熱炉２
において所定の温度まで加熱されその後穿孔機３により
中空素管４を得る。穿孔機としては、プレスロールピア
サー、図示していないマンネスマンピアサーなどがあ
る。その後マンドレルミル法では延伸連続圧延機である
マンドレルミル７によって延伸圧延された後、再加熱炉
８により所定の温度に加熱され仕上げ圧延機であるスト
レッチレデューサー９で所定の外径に圧延成形され仕上
管１０となる。また、マンドレルミル７の前に肉厚を減
じると共に長さを伸ばすエロンゲータミル５、外径を絞
るホローシェルレデューサー６が設置される場合もあ
る。一方プラグミル法においては、中空素管４はエロン
ゲータミル５により肉厚を減じると共に長さを伸ばす延
伸圧延が行われ、次いでプラグミル１１により減肉延伸
されリーラーミル１２により内外面を平滑に仕上げる。
その後再加熱炉８により所定の温度に加熱されサイザー
ミル１３により所定の外径に圧延成形され仕上管１０と
なる。FIG. 1 shows a rolling process. FIG.
1A shows a mandrel mill method, and FIG. 1B shows a plug mill method. As shown in FIG.
Is heated to a predetermined temperature, and then the hollow shell 4 is obtained by the punch 3. Examples of the punch include a press roll piercer and a mannes man piercer not shown. After that, in the mandrel mill method, after being stretched and rolled by a mandrel mill 7 which is a continuous stretching rolling mill, it is heated to a predetermined temperature by a reheating furnace 8 and roll-formed to a predetermined outer diameter by a stretch reducer 9 which is a finishing rolling mill, and finished. Tube 10. In addition, an elongator mill 5 for reducing the thickness and increasing the length and a hollow shell reducer 6 for reducing the outer diameter may be provided in front of the mandrel mill 7. On the other hand, in the plug mill method, the hollow shell 4 is subjected to elongation rolling in which the wall thickness is reduced and the length is increased by an elongator mill 5, then the wall thickness is reduced by a plug mill 11, and the inner and outer surfaces are finished smoothly by a reeler mill 12.
Thereafter, it is heated to a predetermined temperature by the reheating furnace 8 and roll-formed to a predetermined outer diameter by the sizer mill 13 to form the finished tube 10.
【０００４】穿孔機やエロンゲータミル等に使用される
プラグは一般に３％Ｃｒ−１％Ｎｉ系低合金鋼材質が使
用され、断熱性を確保するために熱処理により表層にＦ
ｅＯ、Ｆｅ3Ｏ4等の酸化スケールを形成させる処理が施
される。このようなプラグで炭素鋼に比べて変形抵抗が
高く、表面に酸化スケールが生じにくいステンレス鋼を
圧延すると、プラグの酸化スケールの消耗が速く、酸化
スケールがなくなるとプラグと被圧延材のメタル−メタ
ル接触によりプラグが溶損し、その結果として管内面に
焼付疵が発生する。A plug used in a drilling machine, an elongator mill, or the like is generally made of a 3% Cr-1% Ni-based low alloy steel material.
A process for forming an oxide scale such as eO or Fe 3 O 4 is performed. When stainless steel is rolled with such a plug, the deformation resistance of which is higher than that of carbon steel and oxide scale is not easily generated on the surface, the oxide scale of the plug is rapidly consumed. The plug is melted by the metal contact, and as a result, seizure flaws occur on the inner surface of the tube.
【０００５】そこで、特開昭６３−２８２２４１号公報
においては、Ｃｒ含有量を低減し、地鉄との界面近傍の
酸化スケールをプラグ表面に強固に溶着されるようなＦ
ｅＯ主体の酸化スケールとし、さらにＭｏ、Ｗ、Ｎｂ、
Ｎｉ、Ｃｏ、Ｖを適量添加して高温強度と表面酸化スケ
ールの地鉄への密着性を高めたプラグが提案されてい
る。また、特開平７−６０３１４号公報においては、表
面に厚さ２５０〜１０００μｍの内部酸化型スケール層
を形成したプラグが提案されている。これらプラグは１
３％Ｃｒステンレス鋼の穿孔においては、３％Ｃｒ−１
％Ｎｉ系低合金鋼材質からなるプラグに対して３倍以上
の寿命延長効果が認められる。しかしながら、１３％Ｃ
ｒステンレス鋼よりさらに変形抵抗の高いＳＵＳ３０
４、ＳＵＳ３１６等のオーステナイト系ステンレス鋼の
穿孔においては、それらプラグの寿命は２倍程度であっ
た。Therefore, Japanese Patent Application Laid-Open No. 63-282241 discloses a method in which the Cr content is reduced and an oxide scale near the interface with the base iron is firmly welded to the plug surface.
eO-based oxide scale, Mo, W, Nb,
Plugs have been proposed in which appropriate amounts of Ni, Co, and V are added to increase the high-temperature strength and the adhesion of the surface oxide scale to the base iron. Further, Japanese Patent Application Laid-Open No. 7-60314 proposes a plug having an internal oxidized scale layer having a thickness of 250 to 1000 μm on the surface. These plugs are 1
In drilling 3% Cr stainless steel, 3% Cr-1
The effect of extending the life of the plug made of% Ni-based low alloy steel material by 3 times or more is recognized. However, 13% C
SUS30 with higher deformation resistance than stainless steel
4. In drilling austenitic stainless steel such as SUS316, the life of those plugs was about twice as long.
【０００６】[0006]
【発明が解決しようとする課題】本発明は、上述したよ
うな事情を鑑みてなされたものであって、ステンレス継
目無鋼管を製造する際に、寿命の長い工具およびその製
造方法を提供することを目的とする。SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a tool having a long life and a method of manufacturing the same when manufacturing a stainless seamless steel pipe. With the goal.
【０００７】[0007]
【課題を解決するための手段】本発明者らは、オーステ
ナイト系ステンレス鋼圧延時においてもプラグ表面に形
成された酸化スケールが早期に摩滅したり、剥ぎ取られ
たりしないようにするため、鋭意研究を重ねた結果、高
温硬度の高いＦｅＣｒ2Ｏ4を主体とした酸化スケール中
に、金属片を介在させることで、酸化スケールが地鉄よ
り剥離しにくく、かつ摩滅しにくくなることを見出し
た。Means for Solving the Problems The inventors of the present invention have conducted intensive studies to prevent the oxide scale formed on the plug surface from being worn away or stripped off early even during the rolling of austenitic stainless steel. As a result, it was found that, by interposing metal pieces in an oxide scale mainly composed of FeCr 2 O 4 having high high-temperature hardness, the oxide scale was less likely to peel off from the ground iron and to be less liable to wear.
【０００８】従来より用いられている３％Ｃｒ−１％Ｎ
ｉ系ではＦｅＯ主体のスケールであり、スケール中に金
属片がほとんど存在しない。ＦｅＯを主体としたスケー
ルは潤滑性に優れるものの、スケールと地鉄との密着性
が十分でないため、１３％Ｃｒ鋼等のステンレス鋼を圧
延すると、スケールが早期に剥離及び摩滅する。Conventionally used 3% Cr-1% N
In the i-system, the scale is mainly composed of FeO, and almost no metal pieces exist in the scale. Although the scale mainly composed of FeO has excellent lubricity, the adhesion between the scale and the ground iron is not sufficient. Therefore, when stainless steel such as 13% Cr steel is rolled, the scale is separated and worn out at an early stage.
【０００９】特開平７−６０３１４号公報においては、
Ｎｉが濃縮した金属片が分散された厚い酸化スケールが
提案されているが、酸化スケールがＦｅＯを主体とした
ものであるため、酸化スケールの高温硬度が不十分であ
り摩滅が速く、オーステナイト系ステンレス鋼の穿孔に
おいては、プラグ寿命は３％Ｃｒ−１％Ｎｉ系プラグの
２倍程度であった。In JP-A-7-60314,
A thick oxide scale in which metal pieces enriched with Ni are dispersed has been proposed. However, since the oxide scale is mainly composed of FeO, the high-temperature hardness of the oxide scale is insufficient, the wear is fast, and the austenitic stainless steel is used. In drilling steel, the plug life was about twice that of a 3% Cr-1% Ni-based plug.
【００１０】本発明においては、厚いＦｅＣｒ2Ｏ4を形
成させるため、Ｃｒ含有量を所定の範囲に調整し、Ｆｅ
Ｃｒ2Ｏ4を主体とした酸化スケール中にＮｉが濃化した
金属片を介在させるため、適量のＮｉを添加した。この
ような鋼材を１２５０℃で８時間加熱して生成した酸化
スケールを図２に示す。空隙が極めて少なく、金属片を
多数含んだＦｅＣｒ2Ｏ4を主体とした厚い酸化スケール
となっている。即ち、図２（ａ）は、酸化スケールの断
面を示す顕微鏡写真であり、そして、図２（ｂ）は、図
２（ａ）のＩ部の拡大顕微鏡写真で、図２（ｃ）は、図
２（ａ）のＩＩ部の拡大顕微鏡写真である。In the present invention, in order to form a thick FeCr 2 O 4 , the Cr content is adjusted to a predetermined range, and
An appropriate amount of Ni was added in order to interpose a metal piece enriched with Ni in an oxide scale mainly composed of Cr 2 O 4 . FIG. 2 shows an oxide scale formed by heating such a steel material at 1250 ° C. for 8 hours. The thickness is very small, and the thickness is a thick oxide scale mainly composed of FeCr 2 O 4 containing many metal pieces. That is, FIG. 2A is a photomicrograph showing a cross section of the oxide scale, and FIG. 2B is an enlarged photomicrograph of a portion I in FIG. 2A, and FIG. FIG. 3 is an enlarged micrograph of a portion II in FIG.
【００１１】図２（ｂ）に示すように、酸化スケールの
表面側は、島状に存在する金属片１５（白い粒状部分）
と、これに隣接した酸化物１６（灰色の枝状に連なった
部分）が存在し、残りは空隙（黒い部分）となってい
る。空隙は酸化スケールの下側になるほど減少してい
て、図２（ｃ）に示すように、酸化スケールの下側は、
金属スケールの殆どは枝状に連なった金属片１５（白い
部分）と、これに隣接する酸化物１６（黒い部分）とか
ら構成されている。As shown in FIG. 2B, the surface side of the oxide scale is a metal piece 15 (white granular portion) existing in an island shape.
Then, there is an oxide 16 (a portion connected in a gray branch shape) adjacent thereto, and the rest is a void (a black portion). The voids decrease toward the lower side of the oxide scale, and as shown in FIG.
Most of the metal scale is composed of a metal piece 15 (white portion) connected in a branch shape and an oxide 16 (black portion) adjacent thereto.
【００１２】また、図３の酸化スケールと地鉄界面の断
面の顕微鏡写真に示すように、酸化スケール中の金属片
の一部が地鉄と繋がっているため、酸化スケールが剥離
しにくい状態になっている。Further, as shown in the micrograph of the cross section of the interface between the oxide scale and the ground iron in FIG. 3, since a part of the metal pieces in the oxide scale is connected to the ground iron, the oxide scale is hardly peeled off. Has become.
【００１３】このような酸化スケールを生成したプラグ
によりプラグ寿命が向上するが、さらにプラグ寿命を向
上させることが可能な重要な知見を見出した。本発明者
らは、金属片を多数含有し、ＦｅＣｒ2Ｏ4を主体とした
酸化スケールを表面に形成したプラグにおいて、寿命に
バラツキガみられたため、その原因を検討した。その結
果、比較的寿命の短かったプラグにおいては、プラグ熱
処理時のオーステナイト粒界にあたる位置でスケールが
割れて欠け落ちていることを突き止めた。本発明の目的
を達成するためには、Ｃｒ及びＮｉを添加することにな
るが、このような鋼においては、酸素の拡散が容易なオ
ーステナイト粒界が酸化されて、続いて粒内が酸化され
る。オーステナイト粒径が大きいと単位体積に占める粒
界面積の割合が小さくなるため、粒界での酸化が粒内で
の酸化に対して激しく、圧延時に荷重を受けると、金属
片が多数存在する粒内に対して、金属片がほとんど存在
しない粒界の強度が弱く、粒界でのスケールが割れて欠
け落ちることがある。そこで、オーステナイト粒径を小
さくすれば、粒界及び粒内での酸化が同等になり、均一
で緻密なスケールを得ることで、酸化スケールの割れ及
び剥離が防止できると発想した。Ｃｒを１３％、Ｎｉを
５％含み、Ｔｉの量を変えることで加熱時のオーステナ
イト粒径を３００〜１０００μｍ、２０〜２００μｍと
した鋼片を１２８０℃で４時間加熱した後のスケールを
図４に示した。加熱時のオーステナイト粒径を小さくす
ることで、緻密なスケールを得ることが可能である。加
熱時のスケールを緻密なものとするため、加熱時のオー
ステナイト粒径が２００μｍ以下となるようにすること
が好ましい。Although the life of the plug is improved by the plug having such an oxide scale, it has been found that the plug life can be further improved. The inventors of the present invention have examined the causes of the plugs, which contain a large number of metal pieces and have an oxide scale mainly composed of FeCr 2 O 4 formed on the surface, because the life of the plugs varies. As a result, it was found that in the plug having a relatively short life, the scale was cracked and chipped off at the position corresponding to the austenite grain boundary during the plug heat treatment. In order to achieve the object of the present invention, Cr and Ni are added, but in such a steel, austenite grain boundaries where oxygen is easily diffused are oxidized, and then intragranular oxidization is performed. You. When the austenite grain size is large, the ratio of the grain boundary area to the unit volume becomes small, so that the oxidation at the grain boundary is more intense than the oxidation within the grains, and when a load is applied during rolling, the grains with many metal fragments are present. The strength of the grain boundary where almost no metal pieces are present is low, and the scale at the grain boundary may crack and chip off. Then, it was conceived that if the austenite grain size is reduced, oxidation at the grain boundaries and within the grains becomes equivalent, and a uniform and dense scale can be obtained, whereby cracking and peeling of the oxide scale can be prevented. FIG. 4 shows a scale obtained by heating a steel slab containing 13% of Cr and 5% of Ni and having an austenite grain size of 300 to 1000 μm and 20 to 200 μm by changing the amount of Ti at 1280 ° C. for 4 hours. It was shown to. By reducing the austenite particle size during heating, a dense scale can be obtained. In order to make the scale at the time of heating dense, it is preferable that the austenite particle size at the time of heating is 200 μm or less.
【００１４】本発明は以上に述べた知見を組み合わせて
構成したものであって、その要旨とするところは下記の
通りである。The present invention is constructed by combining the findings described above, and the gist thereof is as follows.
【００１５】すなわち、重量％で、Ｃ：０．０１〜０．
１％、Ｓｉ≦０．５％、Ｍｎ：０．２〜１．０％、Ｃ
ｒ：１１．０〜１５．０％、Ｎｉ：３．０〜７．０％、
Ｍｏ：１．０〜４．０％を含有するか、或いは更にＴ
ｉ：０．０１〜０．１％を含むと共に、残部がＦｅ及び
不可避的不純物である鋼の表面に金属片を含み空隙が少
ない厚さ３００μｍ以上のスケール層を有することを特
徴とする継目無鋼管製造用工具である。さらには、重量
％で、Ｃ：０．０１〜０．１％、Ｓｉ≦０．５％、Ｍ
ｎ：０．２〜１．０％、Ｃｒ：１１．０〜１５．０％、
Ｎｉ：３．０〜７．０％、Ｍｏ：１．０〜４．０％を含
有するか、或いは更にＴｉ：０．０１〜０．１％をを含
むと共に、残部がＦｅ及び不可避的不純物である鋼を、
所定の形状に仕上げた後、１２００〜１３００℃の温度
範囲で４〜１２時間加熱することにより、表面に金属片
を含み空隙が少ない厚さ３００μｍ以上のスケール層を
形成させることを特徴とする継目無鋼管製造用工具の製
造方法である。That is, in weight%, C: 0.01-0.
1%, Si ≦ 0.5%, Mn: 0.2-1.0%, C
r: 11.0 to 15.0%, Ni: 3.0 to 7.0%,
Mo: contains 1.0 to 4.0%, or further contains T
i: a seamless layer comprising 0.01 to 0.1%, the balance being Fe and a scale layer having a thickness of 300 μm or more and having few voids on the surface of steel which is an unavoidable impurity and containing metal pieces. It is a tool for steel pipe production. Further, C: 0.01 to 0.1%, Si ≦ 0.5%, M
n: 0.2 to 1.0%, Cr: 11.0 to 15.0%,
Ni: 3.0 to 7.0%, Mo: 1.0 to 4.0%, or further contains Ti: 0.01 to 0.1%, with the balance being Fe and unavoidable impurities Steel,
After finishing to a predetermined shape, by heating in a temperature range of 1200 to 1300 ° C. for 4 to 12 hours, a scale layer having a thickness of 300 μm or more containing metal pieces on the surface and having few voids is formed. This is a method for producing a tool for producing a steelless pipe.
【００１６】[0016]
【発明の実施の形態】以下に本発明について詳細に説明
する。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
【００１７】まず、鋼成分の限定理由について述べる。First, the reasons for limiting the steel components will be described.
【００１８】Ｃ：０．０１〜０．１％ Ｃは高温強度向上に有効な成分であるが、その含有量が
０．０１％未満ではその効果が小さい。一方、０．１％
を超えると圧延後の冷却で焼き割れが生じやすくなるた
め、その範囲を０．０１〜０．１％とした。C: 0.01-0.1% C is a component effective for improving the high-temperature strength, but if its content is less than 0.01%, its effect is small. On the other hand, 0.1%
If the temperature exceeds the limit, quenching cracks are easily generated by cooling after rolling, so the range is set to 0.01 to 0.1%.
【００１９】Ｓｉ：０．５％以下 Ｓｉは脱酸剤として添加され残存したもので、鋼中に
０．５％を超えて含有されると靭性が低下するため、
０．５％以下とした。Si: 0.5% or less Si is added as a deoxidizing agent and remains, and if it exceeds 0.5% in steel, toughness is reduced.
0.5% or less.
【００２０】Ｍｎ：０．２〜１．０％ Ｍｎは、高温強度向上に有効であるが、０．２％未満で
はその効果が小さく、１．０％を超えて添加すると多量
の介在物を形成し靭性が劣化するため、その範囲を０．
２〜１．０％とした。 Ｃｒ：１１．０〜１５．０％ Ｃｒは、ＦｅＣｒ2Ｏ4の厚さと関係があり本発明におい
ては重要な元素である。Ｃｒ量が１３％でＦｅＣｒ2Ｏ4
の厚さが最大になり、１１％未満及び１５％を超えると
十分な厚さのＦｅＣｒ2Ｏ4が得られない。従って、限定
範囲を１１〜１５％とした。好ましくは１２．５〜１４
%である。Mn: 0.2 to 1.0% Mn is effective for improving high-temperature strength, but its effect is small when it is less than 0.2%, and when it exceeds 1.0%, a large amount of inclusions is formed. The range is set to 0.
2 to 1.0%. Cr: 11.0 to 15.0% Cr is related to the thickness of FeCr 2 O 4 and is an important element in the present invention. Cr content is 13% and FeCr 2 O 4
When the thickness is less than 11% or more than 15%, a sufficiently thick FeCr 2 O 4 cannot be obtained. Therefore, the limited range is set to 11 to 15%. Preferably 12.5-14
%.
【００２１】Ｎｉ：３．０〜７．０％ Ｎｉは、酸化されにくい元素であり、酸化スケール中に
金属片を介在させるための重要な元素である。３．０％
以下では顕著な効果は期待できず、７．０％を超えると
効果が飽和するため、その限定範囲を３．０〜７．０％
とした。Ni: 3.0-7.0% Ni is an element that is not easily oxidized, and is an important element for interposing metal pieces in the oxide scale. 3.0%
Below, a remarkable effect cannot be expected, and if the content exceeds 7.0%, the effect is saturated. Therefore, the limited range is 3.0 to 7.0%.
And
【００２２】Ｍｏ：１．０〜４．０％ Ｍｏは、降温強度の向上に有効な元素であるが、１．０
％未満ではその効果が小さく、４．０％を超えて含有す
るとδフェライトを生成しやすくなり、地鉄表面が割れ
やすくなるため、その限定範囲を１．０〜４．０％とし
た。Mo: 1.0 to 4.0% Mo is an element effective for improving the temperature drop strength.
%, The effect is small, and if the content exceeds 4.0%, δ ferrite is easily formed, and the surface of the base iron is easily cracked. Therefore, the limiting range is set to 1.0 to 4.0%.
【００２３】Ｔｉ：０．０１〜０．１％ Ｔｉは加熱時のオーステナイト粒径に影響を与え、加熱
時のオーステナイト粒径を２００μｍ以下にするため、
必要に応じて０．０１％以上とする。一方、０．１％を
超えると粗大な酸化物や窒化物を形成して靭性を低下さ
せるので、その限定範囲を０．０１〜０．１％とした。Ti: 0.01-0.1% Ti affects the austenite grain size during heating, and reduces the austenite grain size during heating to 200 μm or less.
0.01% or more if necessary. On the other hand, if it exceeds 0.1%, coarse oxides and nitrides are formed and the toughness is reduced, so the limiting range is set to 0.01 to 0.1%.
【００２４】続いて、熱処理条件の限定理由について述
べる。Next, the reasons for limiting the heat treatment conditions will be described.
【００２５】本発明では熱処理温度を１２００℃〜１３
００℃の範囲に規定したが、１２００℃未満では酸化物
生成能力が劣るためであり、１３００℃を超えるとスケ
ール中に空隙が多くなるためである。また、熱処理時間
を４時間〜１２時間と規定したが、４時間未満では十分
な厚さのスケールが得られないためであり、１２時間を
超えると空隙の少ない緻密なスケールの生成量が飽和す
るためである。In the present invention, the heat treatment temperature is set at 1200.degree.
The temperature is specified in the range of 00 ° C., but when the temperature is lower than 1200 ° C., the oxide forming ability is inferior. The heat treatment time is defined as 4 hours to 12 hours. However, if the heat treatment time is less than 4 hours, a scale having a sufficient thickness cannot be obtained. If the heat treatment time exceeds 12 hours, the amount of dense scale with few voids is saturated. That's why.
【００２６】次に、プラグ表面に形成する酸化スケール
の厚さを限定した理由を以下に述べる。Next, the reason why the thickness of the oxide scale formed on the plug surface is limited will be described below.
【００２７】本発明により形成される酸化スケールの形
態は図２に示した通りであり、２層に分類される。同図
中にＩで示した範囲の表層側の酸化スケールは空隙が多
く、金属片の小さいものであるため、圧延中に容易に剥
離しやすく、プラグの耐久性向上への寄与が小さい。一
方、同図中にＩＩで示した範囲の地鉄側の酸化スケール
は空隙が少なく、金属片の多いものであるため、圧延中
に剥離し難く、この酸化スケールの厚さがプラグの寿命
上重要となる。The form of the oxide scale formed according to the present invention is as shown in FIG. 2 and is classified into two layers. Since the oxide scale on the surface layer in the range indicated by I in the figure has many voids and small metal pieces, it easily peels off easily during rolling and contributes little to the improvement of the durability of the plug. On the other hand, the oxide scale on the ground iron side in the range indicated by II in the figure has few voids and many pieces of metal, so it is difficult to peel off during rolling, and the thickness of this oxide scale increases the life of the plug. It becomes important.
【００２８】この、空隙が少なく、金属片の多いＩＩで
示した範囲の酸化スケールが３００μｍ未満では、十分
な断熱効果が得られないばかりか、摩滅により十分な耐
久性が得られないため、３００μｍ以上とした。ＩＩで
示した範囲の酸化スケールの厚さの上限は特に規定しな
いが、本発明の成分において生じる最大厚さは８００μ
ｍ程度である。When the oxide scale in the range indicated by II having a small amount of voids and many metal pieces is less than 300 μm, not only a sufficient heat insulating effect cannot be obtained but also a sufficient durability due to abrasion cannot be obtained. It was above. The upper limit of the thickness of the oxide scale in the range indicated by II is not particularly specified, but the maximum thickness generated in the component of the present invention is 800 μm.
m.
【００２９】ここで、前記のＩＩで示した範囲のスケー
ルの望ましい空隙、金属片、酸化物の割合について説明
する。ＩＩで示した範囲のスケールは、空隙が少ないほ
ど良く、任意に切断した断面全体に対する空隙の面積率
が皆無或は２０％以下であることが望ましい。Here, the desirable ratio of the voids, metal pieces, and oxides in the scale in the range indicated by II will be described. The scale in the range indicated by II is better as the number of voids is smaller, and it is preferable that the area ratio of voids to the entire cross section arbitrarily cut is zero or 20% or less.
【００３０】また、金属片の割合は、任意に切断した断
面全体に対して、金属片の面積率が３０％以上であるこ
とが望ましい。なお、スケール中の金属片の面積率が７
０％を超えると、焼き付きが生じる場合があるため、上
限を７０％とするのが望ましい。Further, the ratio of the metal pieces is desirably such that the area ratio of the metal pieces is 30% or more with respect to the entire section taken arbitrarily. The area ratio of the metal pieces in the scale is 7
If it exceeds 0%, image sticking may occur, so the upper limit is preferably set to 70%.
【００３１】そして、任意に切断した断面全体に対し
て、前記空隙の面積率と前記金属片の面積率を除いた部
分が酸化物の面積率である。The portion excluding the area ratio of the voids and the area ratio of the metal pieces is the area ratio of the oxide with respect to the entire cross section arbitrarily cut.
【００３２】酸化スケール中の空隙、金属片および酸化
物の面積率が上記範囲外であると、酸化スケールは領域
Ｉで示したもののようになり、圧延中に容易に剥離しや
すくなり、望ましくない。If the area ratio of the voids, metal pieces and oxides in the oxide scale is out of the above range, the oxide scale becomes as shown in the region I, and is easily peeled off during rolling, which is not desirable. .
【００３３】[0033]
【実施例】以下、本発明の実施例を説明する。Embodiments of the present invention will be described below.
【００３４】高周波誘導加熱炉にて鋳造した表１に示す
鋼を、所定のプラグ形状に機械加工した後、表１に示す
条件にて熱処理を行った。The steel shown in Table 1 cast in a high-frequency induction heating furnace was machined into a predetermined plug shape, and then heat-treated under the conditions shown in Table 1.
【００３５】熱処理後のプラグを切断し、空隙が少なく
金属片を多数含む地鉄側の酸化スケール（図２中にＩＩ
で示した範囲）の厚さを測定した。After the heat treatment, the plug was cut, and the oxide scale on the base iron side containing a small number of voids and a large number of metal pieces (II in FIG. 2)
(The range indicated by) was measured.
【００３６】辺長８０ｍｍ、長さ１０００ｍｍのオース
テナイト系ステンレス鋼ＳＵＳ３１６Ｌの角材を１１５
０℃に加熱後、上述のようにして得られたプラグを用
い、プレスロールピアサーにて外径９３ｍｍ、肉厚２
３．５ｍｍ、長さ１２４０ｍｍに穿孔した。試験結果を
表１に示す。An austenitic stainless steel SUS316L having a side length of 80 mm and a length of 1000 mm is made of 115
After heating to 0 ° C., using the plug obtained as described above, an outer diameter of 93 mm and a thickness of 2 were obtained using a press roll piercer.
It was perforated to 3.5 mm and length 1240 mm. Table 1 shows the test results.
【００３７】本発明（Ｎｏ．１〜１０）のプラグではオ
ーステナイト系ステンレス鋼を７〜１５本穿孔可能であ
った。With the plugs of the present invention (Nos. 1 to 10), 7 to 15 austenitic stainless steels could be drilled.
【００３８】なお、本発明のプラグの任意に切断した断
面全体に対する空隙の面積率は実質皆無または２０％以
下、金属片の面積率は３０〜７０％の範囲にあり、残部
が酸化物であった。It should be noted that the area ratio of the voids to the arbitrarily cut cross section of the plug of the present invention is substantially zero or less than 20%, the area ratio of the metal pieces is in the range of 30 to 70%, and the remainder is oxide. Was.
【００３９】一方、比較例Ｎｏ．１１ではＣ重量が本発
明の範囲外であるため、穿孔後の冷却過程にて、プラグ
母材に割れが発生した。比較例Ｎｏ．１２では、Ｃｒ重
量が本発明の下限値未満であるため、酸化スケールがＦ
ｅＯを主体としたものとなり早期に摩滅した。比較例Ｎ
ｏ．１３では、Ｃｒ重量が本発明の上限を超えているた
め、酸化スケールの厚さが不十分であり早期に摩滅し
た。比較例Ｎｏ．１４ではＮｉが本発明の下限値未満で
あるため、スケール中に存在する金属片の量が少なく、
スケールが早期に摩滅した。比較例Ｎｏ．１５ではＭｏ
重量が本発明の範囲外であるため、δフェライトが生
じ、プラグ母材がδフェライト、マルテンサイトの２相
組織になり割れが発生した。比較例Ｎｏ．１６〜Ｎｏ．
１８では、熱処理条件が本発明の範囲外であるため、ス
ケールの厚さが不十分で早期に摩滅した。比較例Ｎｏ．
１９は従来より用いられている３％Ｃｒ−１％Ｎｉ系低
合金鋼材質を使用したプラグであり、酸化スケール中に
金属片がほとんど存在しないＦｅＯを主体としたスケー
ルであるため早期に摩滅した。On the other hand, in Comparative Example No. In No. 11, since the C weight was outside the range of the present invention, cracks occurred in the plug base material in the cooling process after drilling. Comparative Example No. In No. 12, since the Cr weight was less than the lower limit of the present invention, the oxide scale was F
It became mainly eO and was quickly worn away. Comparative Example N
o. In No. 13, since the Cr weight exceeded the upper limit of the present invention, the thickness of the oxide scale was insufficient, and the oxide scale was worn out early. Comparative Example No. In No. 14, since Ni is less than the lower limit of the present invention, the amount of metal pieces present in the scale is small,
The scale was worn out early. Comparative Example No. Mo in 15
Since the weight was outside the range of the present invention, δ ferrite was generated, and the plug base material had a two-phase structure of δ ferrite and martensite, and cracks occurred. Comparative Example No. 16-No.
In No. 18, since the heat treatment conditions were out of the range of the present invention, the scale thickness was insufficient and worn out early. Comparative Example No.
Reference numeral 19 denotes a plug using a conventionally used 3% Cr-1% Ni-based low-alloy steel material, which is worn out early because it is a scale mainly composed of FeO in which almost no metal fragments are present in the oxide scale. .
【００４０】[0040]
【表１】 [Table 1]
【００４１】[0041]
【発明の効果】本発明によれば、ステンレス鋼の圧延に
おいて、プラグ寿命が延長できるため、工具使用量（工
具原単位）の低減が図れるほか、プラグ交換のための設
備休止時間を短縮することが可能であり、工業上の効果
が大きい。According to the present invention, the life of the plug can be extended in the rolling of stainless steel, so that the amount of tool used (tool basic unit) can be reduced and the downtime of equipment for plug replacement can be shortened. Is possible, and the industrial effect is great.
【図１】マンドレルミル方式、プラグミル方式による継
目無鋼管製造工程を示す図である。FIG. 1 is a diagram showing a seamless steel pipe manufacturing process by a mandrel mill method and a plug mill method.
【図２】酸化スケールの断面を示す顕微鏡写真である。FIG. 2 is a micrograph showing a cross section of an oxide scale.
【図３】酸化スケール／地鉄界面の酸化スケールの断面
を示す顕微鏡写真である。FIG. 3 is a micrograph showing a cross section of the oxide scale at the oxide scale / base iron interface.
【図４】酸化スケールの形態に及ぼすオーステナイト粒
径の影響の説明を示す顕微鏡写真である。FIG. 4 is a photomicrograph showing the effect of austenite particle size on the morphology of oxide scale.
１ 穿孔機における被圧延材 ２ 加熱炉 ３ 穿孔機 ４ 穿孔機出側の中空素管 ５ エロンゲータ ６ ホローシェルレデューサー ７ マンドレルミル ８ 再加熱炉 ９ ストレッチレデューサー １０ 仕上管 １１ プラグミル １２ リーラーミル １３ サイザーミル １４ 空隙 １５ 金属片 １６ 酸化物 １７ 酸化スケール １８ 地鉄 DESCRIPTION OF SYMBOLS 1 Rolled material in a drilling machine 2 Heating furnace 3 Drilling machine 4 Hollow shell tube on the exit side of a drilling machine 5 Elongator 6 Hollow shell reducer 7 Mandrel mill 8 Reheating furnace 9 Stretch reducer 10 Finishing pipe 11 Plug mill 12 Reeler mill 13 Sizer mill 14 Air gap 15 Metal pieces 16 Oxide 17 Oxide scale 18 Ground iron
フロントページの続き (72)発明者 古庄 弘一 北九州市戸畑区飛幡町１−１ 新日本製鐵 株式会社八幡製鐵所内 (72)発明者 高久 健一 北九州市戸畑区飛幡町１−１ 新日本製鐵 株式会社八幡製鐵所内 (72)発明者 石橋 精二 北九州市戸畑区飛幡町１−１ 新日本製鐵 株式会社八幡製鐵所内Continuing from the front page (72) Inventor Koichi Furusho 1-1, Tobata-cho, Tobata-ku, Kitakyushu Nippon Steel Corporation Inside Yawata Works (72) Inventor Ken-ichi Takaku 1-1, Tobita-cho, Tobata-ku, Kitakyushu Nippon Steel Inside Yawata Works (72) Inventor Seiji Ishibashi 1-1 Nabihatacho, Tobata-ku, Kitakyushu Nippon Steel Inside Yawata Works
Claims (4)
ｉ≦０．５％、Ｍｎ：０．２〜１．０％、Ｃｒ：１１．
０〜１５．０％、Ｎｉ：３．０〜７．０％、Ｍｏ：１．
０〜４．０％を含有し、残部がＦｅ及び不可避的不純物
である鋼の表面に金属片を含み空隙が少ない厚さ３００
μｍ以上のスケール層を有することを特徴とする継目無
鋼管製造用工具。1. C .: 0.01 to 0.1% by weight, S
i ≦ 0.5%, Mn: 0.2 to 1.0%, Cr: 11.
0 to 15.0%, Ni: 3.0 to 7.0%, Mo: 1.
0-4.0%, the balance being Fe and a thickness of 300 with small voids containing metal fragments on the surface of steel, which is an unavoidable impurity.
A seamless steel pipe manufacturing tool having a scale layer of at least μm.
ｉ≦０．５％、Ｍｎ：０．２〜１．０％、Ｃｒ：１１．
０〜１５．０％、Ｎｉ：３．０〜７．０％、Ｍｏ：１．
０〜４．０％、Ｔｉ：０．０１〜０．１％を含有し、残
部がＦｅ及び不可避的不純物である鋼の表面に金属片を
含み空隙が少ない厚さ３００μｍ以上のスケール層を有
することを特徴とする継目無鋼管製造用工具。2. C: 0.01 to 0.1% by weight, S
i ≦ 0.5%, Mn: 0.2 to 1.0%, Cr: 11.
0 to 15.0%, Ni: 3.0 to 7.0%, Mo: 1.
0 to 4.0%, Ti: 0.01 to 0.1%, the balance being Fe and a scale layer with a thickness of 300 μm or more with small voids containing metal pieces on the surface of steel, which is an unavoidable impurity. A tool for producing a seamless steel pipe.
ｉ≦０．５％、Ｍｎ：０．２〜１．０％、Ｃｒ：１１．
０〜１５．０％、Ｎｉ：３．０〜７．０％、Ｍｏ：１．
０〜４．０％を含有し、残部がＦｅ及び不可避的不純物
である鋼を、所定の形状に仕上げた後、１２００〜１３
００℃の温度範囲で４〜１２時間加熱することにより、
表面に金属片を含み空隙が少ない厚さ３００μｍ以上の
スケール層を形成させることを特徴とする継目無鋼管製
造用工具の製造方法。3. C: 0.01 to 0.1% by weight, S:
i ≦ 0.5%, Mn: 0.2 to 1.0%, Cr: 11.
0 to 15.0%, Ni: 3.0 to 7.0%, Mo: 1.
After finishing steel having a content of 0 to 4.0% and a balance of Fe and inevitable impurities to a predetermined shape,
By heating at a temperature range of 00 ° C. for 4 to 12 hours,
A method for manufacturing a seamless steel pipe manufacturing tool, comprising forming a scale layer having a thickness of 300 μm or more and having a small amount of voids and a metal piece on the surface.
ｉ≦０．５％、Ｍｎ：０．２〜１．０％、Ｃｒ：１１．
０〜１５．０％、Ｎｉ：３．０〜７．０％、Ｍｏ：１．
０〜４．０％、Ｔｉ：０．０１〜０．１％を含有し、残
部がＦｅ及び不可避的不純物である鋼を、所定の形状に
仕上げた後、１２００〜１３００℃の温度範囲で４〜１
２時間加熱することにより、表面に金属片を含み空隙が
少ない厚さ３００μｍ以上のスケール層を形成させるこ
とを特徴とする継目無鋼管製造用工具の製造方法。4. C: 0.01 to 0.1% by weight, S
i ≦ 0.5%, Mn: 0.2 to 1.0%, Cr: 11.
0 to 15.0%, Ni: 3.0 to 7.0%, Mo: 1.
After finishing steel having a content of 0 to 4.0% and Ti: 0.01 to 0.1% and a balance of Fe and inevitable impurities into a predetermined shape, the steel is heated to a temperature of 1200 to 1300 ° C. ~ 1
A method for manufacturing a seamless steel pipe manufacturing tool, comprising forming a scale layer having a thickness of 300 μm or more containing metal pieces on the surface and having few voids by heating for 2 hours.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP36890998A JP4258580B2 (en) | 1998-12-25 | 1998-12-25 | Seamless steel pipe manufacturing tool and method for manufacturing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP36890998A JP4258580B2 (en) | 1998-12-25 | 1998-12-25 | Seamless steel pipe manufacturing tool and method for manufacturing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000190008A true JP2000190008A (en) | 2000-07-11 |
| JP4258580B2 JP4258580B2 (en) | 2009-04-30 |
Family
ID=18493067
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP36890998A Expired - Fee Related JP4258580B2 (en) | 1998-12-25 | 1998-12-25 | Seamless steel pipe manufacturing tool and method for manufacturing the same |
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| Country | Link |
|---|---|
| JP (1) | JP4258580B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2011190478A (en) * | 2010-03-12 | 2011-09-29 | Hitachi Ltd | Steam turbine member |
| WO2013080528A1 (en) * | 2011-11-30 | 2013-06-06 | Ｊｆｅスチール株式会社 | Tool for piercing mill |
| JP2021011611A (en) * | 2019-07-08 | 2021-02-04 | 株式会社東芝 | Steel, turbine rotor, and steam turbine |
-
1998
- 1998-12-25 JP JP36890998A patent/JP4258580B2/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2011190478A (en) * | 2010-03-12 | 2011-09-29 | Hitachi Ltd | Steam turbine member |
| WO2013080528A1 (en) * | 2011-11-30 | 2013-06-06 | Ｊｆｅスチール株式会社 | Tool for piercing mill |
| JP2013112869A (en) * | 2011-11-30 | 2013-06-10 | Jfe Steel Corp | Tool for piercing-rolling |
| US9194031B2 (en) | 2011-11-30 | 2015-11-24 | Jfe Steel Corporation | Tool for piercing mill |
| JP2021011611A (en) * | 2019-07-08 | 2021-02-04 | 株式会社東芝 | Steel, turbine rotor, and steam turbine |
| JP7258678B2 (en) | 2019-07-08 | 2023-04-17 | 株式会社東芝 | steel, turbine rotors and steam turbines |
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