JPH06158157A - Production of cold rolled special steel surface decarburized steel strip - Google Patents
Production of cold rolled special steel surface decarburized steel stripInfo
- Publication number
- JPH06158157A JPH06158157A JP34159192A JP34159192A JPH06158157A JP H06158157 A JPH06158157 A JP H06158157A JP 34159192 A JP34159192 A JP 34159192A JP 34159192 A JP34159192 A JP 34159192A JP H06158157 A JPH06158157 A JP H06158157A
- Authority
- JP
- Japan
- Prior art keywords
- steel strip
- layer
- decarburization
- steel
- decarburized
- 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.)
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- Heat Treatment Of Sheet Steel (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、各種機械部品、工具
類、および刃物等の材料として使用される、表面に均一
な脱炭層が形成された球状化炭化物組織を有する高炭素
鋼板の製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high carbon steel sheet having a spheroidized carbide structure having a uniform decarburized layer formed on its surface, which is used as a material for various machine parts, tools, blades and the like. Regarding
【０００２】[0002]
【従来の技術】各種機械部品、工具鋼、および刃物等の
材料として使用される高炭素鋼板は、硬度、耐摩耗性等
にすぐれていると共に、良好な加工性や被削性等を有し
ていなければならない。従来より、上記高炭素鋼板は、
冷延鋼帯を球状化焼鈍処理した後、調質圧延し、ついで
脱炭焼鈍する工程を経て製造されている。球状化処理
は、熱延鋼帯または、熱間圧延後、冷間圧延した冷延鋼
帯の生地組織（ラメラーパーライト組織）の炭化物（セ
メンタイト）を凝集させ、球状化した炭化物が均一に分
散した組織（球状化炭化物組織）に変えることにより、
延性、耐衝撃性等を高めると共に、冷間塑性加工性及び
被削性等を良好なものとするのであり、その球状化焼鈍
処理は、鋼帯のタイトコイルを、還元性雰囲気（代表的
には、水素ガス約１０容積％を含むＨ2 −Ｎ2 混合ガス
であるＨＮガス等）において、Ａ1 変態点の直下ないし
それより約１００℃低い温度に適当時間保持することに
より行われる。他方、脱炭焼鈍処理は、脱炭性還元雰囲
気（代表的には、水素ガス約７５容積％を含むＨ2 −Ｎ
2 混合ガスであるＡＸガス等）中、鋼帯のオープンコイ
ルを、Ａ1 変態点直下ないしそれより約１２０℃低い温
度域に適当時間保持することにより行われる。鋼帯表面
に脱炭層を形成するのは、焼入れ・焼戻し等の熱処理後
に行われる打抜き、曲げ、絞り等における良好な加工性
を確保するためであり、その脱炭層は鋼帯表面の全体に
亘つて均一な所定の層厚に形成されなければならず、ま
た脱炭層と内側の球状化炭化物組織との境界は明瞭であ
ることが望まれる。2. Description of the Related Art High carbon steel sheets used as materials for various machine parts, tool steels, blades and the like have excellent hardness, wear resistance and the like and have good workability and machinability. Must be Conventionally, the high carbon steel plate is
After cold-rolled steel strip is spheroidized, it is temper-rolled and then decarburized and annealed. The spheroidizing treatment agglomerates the carbide (cementite) of the texture structure (lamellar pearlite structure) of the hot-rolled steel strip or the cold-rolled cold-rolled steel strip after hot rolling, and the spheroidized carbide is uniformly dispersed. By changing the structure (spheroidized carbide structure),
In addition to improving ductility, impact resistance, etc., it also improves cold plastic workability and machinability.The spheroidizing annealing process is performed in a tight coil of steel strip in a reducing atmosphere (typically Is performed by maintaining the temperature in the H 2 -N 2 mixed gas containing about 10% by volume of hydrogen gas at a temperature just below the A 1 transformation point or about 100 ° C. lower than that. On the other hand, the decarburization annealing treatment is performed in a decarburizing reducing atmosphere (typically H 2 -N containing about 75% by volume of hydrogen gas).
2 mixed gas, such as AX gas), by holding the open coil of the steel strip in a temperature range immediately below the A 1 transformation point or lower by about 120 ° C. for an appropriate time. The decarburization layer is formed on the surface of the steel strip in order to ensure good workability in punching, bending, drawing, etc., which is performed after heat treatment such as quenching and tempering. Therefore, it is desired that the decarburized layer and the inner spheroidized carbide structure have a clear boundary between them.
【０００３】[0003]
【発明が解決しようとする課題】上記製造工程を経て得
られる従来の表面脱炭高炭素鋼帯は、生地組織の炭化物
の球状化は十分に行われているが、表面の脱炭深さ（脱
炭層厚さ）のバラツキが大きく、しかも深さ方向の脱炭
カーブ（Ｃ濃度の勾配）が緩やかで、脱炭層が不明瞭で
あるという欠点がある。本発明は上記に鑑み、生地組織
が十分に球状化され、かつ表面に均一で精度良く脱炭層
が形成された鋼帯を製造する方法を提供するものであ
る。In the conventional surface-decarburized high-carbon steel strip obtained through the above-mentioned manufacturing process, although the spheroidizing of the carbide of the dough structure is sufficiently performed, the surface decarburization depth ( The decarburization layer has a large variation and the decarburization curve (gradient of C concentration) in the depth direction is gentle, so that the decarburization layer is unclear. In view of the above, the present invention provides a method for producing a steel strip in which the dough structure is sufficiently spheroidized, and a decarburized layer is uniformly formed on the surface with high accuracy.
【０００４】[0004]
【課題を解決するための手段および作用】本発明の冷延
特殊鋼表面脱炭鋼帯の製造方法は、ラメラーパーライト
組織を有する高炭素鋼冷延鋼帯を、オープンコイル焼鈍
炉において、脱炭雰囲気中、Ａ1変態点直下〜Ａ1 変態
点−１２０℃の温度域で、１〜１５時間を要して焼鈍処
理することにより、表面に脱炭層を形成すると共に、脱
炭層の内側領域の生地組織を球状化炭化物組織とするこ
とを特徴としている。Means and Actions for Solving the Problem A method for producing a cold-rolled special steel surface decarburized steel strip according to the present invention is to decarburize a high carbon steel cold-rolled steel strip having a lamellar pearlite structure in an open coil annealing furnace. atmosphere, at a temperature range of a 1 transformation point just below to a 1 transformation point -120 ° C., by annealing over a period of 1 to 15 hours, to form a decarburized layer on the surface, of the decarburized layer of the inner region It is characterized in that the material structure is a spheroidized carbide structure.
【０００５】[0005]
【作用】鋼帯表面の脱炭は、鋼中の固溶Ｃが表面へ拡散
してＣＯガスとなつて脱出する現象であり、鋼中のＣ量
が固溶限以下になると、炭化物（セメンタイト）がα−
Ｆｅ（フエライト相）とＣとに分解消失して脱炭反応は
進行する。球状化焼鈍処理が施された鋼板は、図２
（ａ）に模式的に示すようにフエライト（α−Ｆｅ）基
地（図中、白地）に球状化炭化物Ｓｃが分散した組織を
有し、その炭化物は粗大なため、α−ＦｅとＣへの分解
反応を生じ難く、反面炭化物粒子相互間のフエライト相
が広い領域に存在しているので、フエライト相中の固溶
Ｃの拡散は容易である。従つて、その脱炭焼鈍処理にお
いては図２（ｂ）のように、表面から深部に亘りＣ濃度
の勾配が緩やかな脱炭を生じ、表面脱炭層Ｄｃと内側の
球状化炭化物組織との境界も不明となる。これに対し、
冷間圧延ままの鋼帯は、図１（ａ）に示すように、その
ラメラーパ−ライト組織Ｌｐ（パーライト組織は圧延方
向に延伸した変形集合組織を呈している）の炭化物（セ
メンタイト）は微細で、かつα−Ｆｅ（図中、白地）は
細かく分断されている。そのため、上記焼鈍処理におい
ては、炭化物が微細であることにより表層部では炭化物
の分解消失と固溶Ｃの表面からの脱出が容易である一
方、深部では細かく分断して存在するα−Ｆｅにより固
溶Ｃの拡散が妨げられ、その領域の炭化物の分解消失反
応も抑制される。従つて、冷間圧延ままの鋼帯に上記条
件の焼鈍処理を行う本発明においては、表層の脱炭反応
は、脱炭層とその内側の未脱炭層との間のＣ濃度勾配が
急峻な状態を保持しながら進行し、その一方において内
側の生地組織の炭化物の球状化反応が進行する。その結
果、同図（ｂ）に示すように境界の鮮明な脱炭層Ｄｃを
表面に有し、内側は十分に球状化した鋼帯が得られる。[Function] Decarburization on the surface of a steel strip is a phenomenon in which solid solution C in the steel diffuses to the surface and escapes by forming CO gas, and when the amount of C in the steel falls below the solid solution limit, it is a carbide (cementite). ) Is α-
Decomposition and disappearance into Fe (ferrite phase) and C progresses the decarburization reaction. The steel sheet that has been subjected to the spheroidizing annealing is shown in FIG.
As schematically shown in (a), it has a structure in which spheroidized carbides Sc are dispersed in a ferrite (α-Fe) matrix (white background in the figure), and since the carbides are coarse, α-Fe and C The decomposition reaction is unlikely to occur, and on the other hand, the ferrite phase between the carbide particles is present in a wide area, so that the solid solution C in the ferrite phase is easily diffused. Therefore, in the decarburization annealing treatment, as shown in FIG. 2B, decarburization with a gradual C concentration gradient occurs from the surface to the deep portion, and the boundary between the surface decarburized layer Dc and the inside spheroidized carbide structure is generated. Will also be unknown. In contrast,
As shown in FIG. 1 (a), the as-cold-rolled steel strip has fine lamellar pearlite structure Lp (pearlite structure exhibits a deformed texture extending in the rolling direction) with fine carbides (cementite). , And α-Fe (white background in the figure) is finely divided. Therefore, in the above-mentioned annealing treatment, since the carbides are fine, the decomposition and disappearance of the carbides and the escape of the solid solution C from the surface are easy at the surface layer portion, while the α-Fe which is finely divided and exists at the deep portion makes it hard to be solidified. The diffusion of molten C is hindered, and the decomposition and disappearance reaction of the carbide in that region is also suppressed. Therefore, in the present invention in which the as-cold-rolled steel strip is annealed under the above conditions, the decarburization reaction of the surface layer is a state in which the C concentration gradient between the decarburized layer and the undecarburized layer inside is steep. Is maintained, and on the other hand, the spheroidizing reaction of the carbide of the inner dough tissue proceeds. As a result, a steel strip having a decarburized layer Dc with a sharp boundary on the surface and a sufficiently spherical inside is obtained as shown in FIG.
【０００６】以下、本発明について詳しく説明する。本
発明によれば、冷間圧延された高炭素鋼帯は、オープン
コイルとして脱炭性還元雰囲気下にバツチ焼鈍処理が施
される。その焼鈍処理における脱炭性還元雰囲気ガス
は、適当な露点に調節されたＨ2−Ｎ2 混合ガスが適用
される。その混合ガスの水素ガス濃度は、約３３〜９０
容積％（以下、単に「％」）が適当である。水素ガス濃
度が約３３％に満たないと、その雰囲気は鋼中鉄分に対
して酸化性となり、表面精度や美麗さが損なわれ、他方
９０％を越える高濃度では、鋼中炭素に対する脱炭性が
弱く、脱炭反応を十分に進めることが困難となるからで
ある。また、上記混合ガスの露点は、約２０〜６５℃の
範囲に調節されることが望ましい。露点が２０℃より低
いと、鋼帯表面における脱炭反応（Ｃ＋Ｈ2 Ｏ→ＣＯ＋
Ｈ2 ）を十分に進めることが困難であり、他方６５℃を
越えるような高い露点の場合には、鋼帯表面の酸化（ス
ケールの発生）が無視できなくなるからである。The present invention will be described in detail below. According to the present invention, the cold-rolled high carbon steel strip is subjected to the batch annealing treatment as an open coil in a decarburizing reducing atmosphere. As the decarburizing reducing atmosphere gas in the annealing treatment, a H 2 —N 2 mixed gas whose dew point is adjusted is applied. The hydrogen gas concentration of the mixed gas is about 33 to 90.
Volume% (hereinafter, simply “%”) is suitable. If the hydrogen gas concentration is less than about 33%, the atmosphere becomes oxidizable to the iron content in the steel, and the surface accuracy and beauty are impaired. On the other hand, if the concentration exceeds 90%, the carbon content in the steel is decarburizable. Is weak, and it becomes difficult to sufficiently advance the decarburization reaction. In addition, it is desirable that the dew point of the mixed gas be adjusted in the range of approximately 20 to 65 ° C. If the dew point is lower than 20 ° C, the decarburization reaction (C + H 2 O → CO +) on the steel strip surface
This is because it is difficult to sufficiently advance H 2 ) and, on the other hand, in the case of a high dew point exceeding 65 ° C., oxidation (generation of scale) on the surface of the steel strip cannot be ignored.
【０００７】焼鈍処理における均熱温度は、Ａ1 変態点
（以下、単に「Ａ1 点」）の直下ないしＡ1 点より約１
２０℃低い温度（Ａ1 点−１２０℃）の範囲に規制され
る。Ａ1 点直下を上限とするのは、オーステナイト相の
生成を回避するためである。他方、Ａ1 点−１２０℃を
下限とするのは、それより低い温度では、表層の固溶Ｃ
の拡散速度、および鋼帯表面の脱炭反応（Ｃ＋Ｈ2 Ｏ→
ＣＯ＋Ｈ2 ）の進行が緩慢となり、脱炭層の形成とその
内側の炭化物の球状化を効率良く短時間で達成すること
が困難ないし不可能となるからである。殊に、処理の長
時間化は、表面から深さ方向のＣ濃度の勾配を緩慢化
し、脱炭層の不明確化を助長する。このため、均熱温度
はＡ1 点−１２０℃以上であることを要する。好ましく
はＡ1 点−７０℃を下限温度とする。The soaking temperature in the annealing treatment is about 1 below the A 1 transformation point (hereinafter, simply “A 1 point”) or from the A 1 point.
It is regulated within the range of 20 ° C lower temperature (A 1 point-120 ° C). The reason why the upper limit of A 1 point is set is to avoid generation of an austenite phase. On the other hand, the lower limit of A 1 point −120 ° C. is that the solid solution C of the surface layer is lower than that.
Diffusion rate and decarburization reaction of steel strip surface (C + H 2 O →
This is because the progress of CO + H 2 ) becomes slow, and it becomes difficult or impossible to efficiently form the decarburized layer and spheroidize the carbide inside thereof in a short time. In particular, if the treatment time is prolonged, the gradient of the C concentration in the depth direction from the surface is slowed down and the decarburization layer is unclear. Therefore, the soaking temperature needs to be A 1 point −120 ° C. or higher. Preferably, A 1 point −70 ° C. is the lower limit temperature.
【０００８】焼鈍処理時間（均熱温度での保持時間）
は、均熱温度や鋼帯の処理重量（炉内装入量）等により
異なるが、概ね１〜１５時間の範囲内で適宜設定すれば
よい。所定時間加熱保持した後、徐冷して焼鈍処理を完
了する。Annealing treatment time (holding time at soaking temperature)
May vary depending on the soaking temperature, the treated weight of the steel strip (amount of the furnace interior), and may be appropriately set within the range of about 1 to 15 hours. After heating and holding for a predetermined time, the material is gradually cooled to complete the annealing treatment.
【０００９】こうして得られる鋼帯は、全表面に亘り所
定の層厚を有する脱炭層が均一に形成され、例えばその
５０％脱炭層の層厚は約２２０〜２５０μｍで、層厚の
バラツキは約０〜３０μｍと小さく、脱炭カーブは急峻
で明瞭な層境界を有している。また、内側領域は炭化物
が十分に球状化された組織を有している。焼鈍処理後の
鋼帯は、常法に従つて形状矯正および降伏点伸びの解消
等のための調質圧延が施されて最終製品に仕上げられ
る。In the steel strip thus obtained, a decarburized layer having a predetermined layer thickness is uniformly formed over the entire surface. For example, the 50% decarburized layer has a layer thickness of about 220 to 250 μm and a variation of the layer thickness is about. The decarburization curve is as small as 0 to 30 μm and has a sharp and clear layer boundary. Further, the inner region has a structure in which carbide is sufficiently spheroidized. The steel strip after the annealing treatment is subjected to temper rolling for the purpose of straightening the shape and eliminating elongation at the yield point according to a conventional method to finish it into a final product.
【００１０】なお、本発明における高炭素鋼帯とは、代
表的にはＣ含有量約０．３％〜２．０％のリムド炭素
鋼、キルド炭素鋼鋼（アルミキルド、シリコンキルド、
チタンキルド）であるが、これに限定されず、材質の改
善を目的として少量の合金元素、例えば０．３％以下の
Ｎｉ、０．３％以下のＣｒ、０．４５％以下のＳｉ、
０．５〜０．８％以下のＭｎ等の一種ないし二種以上の
元素を含有する鋼種をも包含し、これらの高炭素鋼に上
記焼鈍処理を施すことにより上記所定の効果を得ること
ができる。The high carbon steel strip in the present invention is typically a rimmed carbon steel having a C content of about 0.3% to 2.0%, a killed carbon steel (aluminum killed, silicon killed,
Titanium killed), but not limited to this, for the purpose of improving the material, a small amount of alloying elements such as 0.3% or less Ni, 0.3% or less Cr, 0.45% or less Si,
A steel type containing one or more elements such as Mn in an amount of 0.5 to 0.8% or less may be included, and the above predetermined effects may be obtained by subjecting these high carbon steels to the annealing treatment. it can.
【００１１】[0011]
〔Ｉ〕供試鋼板の製造 冷間圧延後のＳ５５Ｃ炭素鋼冷延鋼帯コイル（板幅：９
１４ｍｍ、板厚：２．２１ｍｍ）をオープンコイルに巻
き直してバツチ式焼鈍炉に装入し、脱炭性還元雰囲気で
の焼鈍処理を行つた。 （１）鋼帯サイズ 板厚 ２．２１ｍｍ、板幅 ９１４
ｍｍ （２）処理量 ５〜６ｔｏｎ （３）雰囲気 ７５％Ｈ2 −Ｎ2 （ＡＸガス）、露点＋
５０℃。 （４）均熱温度 ７００℃ （５）処理時間 ７．５時間 上記焼鈍処理の後、調質圧延（圧下率１％）を行つて供
試鋼板（発明例）を得た。[I] Manufacture of test steel sheet S55C carbon steel cold rolled steel strip coil after cold rolling (sheet width: 9
(14 mm, plate thickness: 2.21 mm) was rewound into an open coil, charged into a batch annealing furnace, and annealed in a decarburizing reducing atmosphere. (1) Steel strip size, plate thickness 2.21 mm, plate width 914
mm (2) Treatment amount 5 to 6 tons (3) Atmosphere 75% H 2 —N 2 (AX gas), dew point +
50 ° C. (4) Soaking temperature 700 ° C. (5) Treatment time 7.5 hours After the above annealing treatment, temper rolling (reduction ratio 1%) was performed to obtain a test steel sheet (invention example).
【００１２】比較例として、上記と同一材種の冷延鋼帯
について、球状化焼鈍処理→調質圧延（圧下率２％）→
脱炭焼鈍処理→調質圧延（圧下率２％）の工程からなる
従来の製造法により供試鋼板（従来例）を得た。球状化
焼鈍処理および脱炭焼鈍処理はそれぞれ次の条件で行つ
た。球状化焼鈍処理 （ｉ）処理量 １２〜１３ｔｏｎ （ｉｉ）雰囲気 ２．１％Ｈ2 −２．５％ＣＯ−Ｎ
2 （ＮＸガス）、露点−６０℃ （ｉｉｉ）灼熱温度 ６２０℃ （ｉｖ）処理時間 １３時間（炉冷 ２時間）脱炭焼鈍処理 （ｉ）処理量 ５〜６ｔｏｎ （ｉｉ）雰囲気 ７５％Ｈ2 −Ｎ2 （ＡＸガス）、露点
＋５０℃ （ｉｉｉ）灼熱温度 ７００℃ （ｉｖ）処理時間 ７．５時間As a comparative example, a cold-rolled steel strip of the same grade as the above is subjected to spheroidizing annealing → temper rolling (reduction rate 2%) →
A test steel sheet (conventional example) was obtained by a conventional manufacturing method including a process of decarburization annealing → temper rolling (rolling reduction rate: 2%). The spheroidizing annealing treatment and the decarburizing annealing treatment were performed under the following conditions. Spheroidizing annealing (i) Treatment amount 12 to 13 ton (ii) atmosphere 2.1% H 2 -2.5% CO-N
2 (NX gas), dew point −60 ° C. (iii) Burning temperature 620 ° C. (iv) Treatment time 13 hours (furnace cooling 2 hours) Decarburization annealing treatment (i) Treatment amount 5 to 6 tons (ii) Atmosphere 75% H 2 -N 2 (AX gas), dew point + 50 ° C. (iii) Burning temperature 700 ° C. (iv) Treatment time 7.5 hours
【００１３】〔ＩＩ〕鋼板の焼鈍品質 （１）脱炭深さの測定 各供試鋼帯のトツプ側およびボトム側から試験片を採取
し、ＪＩＳ Ｇ ０５５８の規定に準拠し、顕微鏡観察
により５０％脱炭深さを測定した。表１は５０％脱炭層
深さ〔ＤＭ−Ｓ（５０）〕を示している（ｎ数：発明例
１２、従来例２４）。発明例の鋼板は、脱炭焼鈍を、球
状化焼鈍処理とは独立した工程として行う従来法による
鋼板と同等の脱炭深さを有し、脱炭深さのバラツキはほ
ぼ半分に低減していることがわかる。[II] Annealing Quality of Steel Sheet (1) Measurement of Decarburization Depth Test pieces were taken from the top side and the bottom side of each steel strip to be tested, and microscopic observation was performed according to JIS G 0558 to observe 50. % Decarburization depth was measured. Table 1 shows the depth of 50% decarburized layer [DM-S (50)] (n number: Inventive Example 12, Conventional Example 24). The steel sheet of the invention example has a decarburization depth equivalent to that of the steel sheet according to the conventional method in which decarburization annealing is performed as a process independent of the spheroidizing annealing treatment, and the variation in the decarburization depth is reduced to almost half. You can see that
【００１４】[0014]
【表１】 [Table 1]
【００１５】（２）表層近傍のミクロ組織 図３は発明例の供試鋼板、図４は従来例の供試鋼板につ
いて、それぞれの表層近傍のミクロ組織を示している
（倍率 ×１００）。図中の白地はフエライト生地であ
り、黒い部分はセメンタイトである。図３（発明例）に
おける１００％脱炭深さは約６０μｍ、５０％脱炭深さ
は約２３０μｍであり、図４（従来例）における１００
％脱炭深さは約４０μｍ、５０％脱炭深さは約２００μ
ｍである。図３と図４との比較から明らかなように、発
明例の供試鋼板（図３）の表層近傍組織は、明確な表面
脱炭層が形成されており、従来例のもの（図４）に比べ
てＣ濃度勾配は急峻である。(2) Microstructure in the vicinity of the surface layer FIG. 3 shows the microstructure in the vicinity of the surface layer of the sample steel sheet of the invention example, and FIG. 4 shows the microstructure of the sample steel sheet in the conventional example (magnification × 100). The white background in the figure is the ferrite material, and the black part is the cementite. The 100% decarburization depth in FIG. 3 (invention example) is about 60 μm, and the 50% decarburization depth is about 230 μm.
% Decarburization depth is about 40μm, 50% decarburization depth is about 200μ
m. As is clear from the comparison between FIG. 3 and FIG. 4, the surface steel structure near the surface layer of the test steel sheet of the invention example (FIG. 3) has a clear surface decarburized layer, which is similar to that of the conventional example (FIG. 4). In comparison, the C concentration gradient is steeper.
【００１６】（３）球状化炭化物組織 図５は、発明例の供試鋼板について表面脱炭層の内側領
域の生地組織を、図６は従来例の供試鋼板における表面
脱炭層の内側の生地組織をそれぞれ示している（倍率
×４００倍）。発明例の供試鋼板の生地組織は球状化し
た炭化物（セメンタイト）が均一に分散し、従来例の供
試鋼板と同等の健全な球状化炭化物組織を有しているこ
とがわかる。(3) Spheroidized Carbide Structure FIG. 5 shows the dough structure inside the surface decarburized layer of the test steel sheet of the invention example, and FIG. 6 shows the dough structure inside the surface decarburized layer of the conventional test steel sheet. Respectively (magnification
× 400 times). It can be seen that the dough structure of the test steel sheet of the invention example has a spheroidized carbide (cementite) uniformly dispersed and has a sound spheroidized carbide structure equivalent to that of the test steel sheet of the conventional example.
【００１７】[0017]
【発明の効果】本発明方法により製造される高炭素鋼表
面脱炭鋼板は、従来法に比べて、表面脱炭層が均一で、
脱炭深さのバラツキが小さく、かつ内側に球状化率の高
い良好な球状化炭化物組織を有すると共に、脱炭層と球
状化炭化物組織層との境界が明確である。従つて、各種
機械部品、工具類、刃物等の材料として好適である。し
かも、従来の製造法では、球状化焼鈍処理と脱炭焼鈍処
理とが個別の工程として行われるのに対し、本発明方法
によれば、表面脱炭層の形成とその内側の球状化炭化物
組織の形成を一工程の焼鈍処理により完結することがで
き、従つて製造工程の簡略化および製造コストの低減効
果も大である。The high carbon steel surface decarburized steel sheet produced by the method of the present invention has a uniform surface decarburized layer as compared with the conventional method,
The decarburization depth has a small variation and has a good spheroidized carbide structure with a high spheroidization rate inside, and the boundary between the decarburized layer and the spheroidized carbide structure layer is clear. Therefore, it is suitable as a material for various machine parts, tools, blades and the like. Moreover, in the conventional manufacturing method, while the spheroidizing annealing treatment and the decarburizing annealing treatment are performed as separate steps, according to the method of the present invention, the formation of the surface decarburized layer and the spheroidized carbide structure inside thereof are formed. The formation can be completed by a one-step annealing treatment, so that the manufacturing process can be simplified and the manufacturing cost can be reduced.
【図１】本発明による高炭素鋼冷延鋼帯の焼鈍処理にお
ける表面脱炭層と内側の球状化炭化物組織の形成機構を
模式的に示す図である。FIG. 1 is a diagram schematically showing a formation mechanism of a surface decarburized layer and an inner spheroidized carbide structure in an annealing treatment of a high carbon steel cold rolled steel strip according to the present invention.
【図２】従来法による球状化焼鈍処理後の高炭素鋼帯の
脱炭焼鈍処理における脱炭層の形成機構を模式的に示す
図である。FIG. 2 is a diagram schematically showing a decarburization layer forming mechanism in decarburization annealing treatment of a high carbon steel strip after spheroidizing annealing treatment by a conventional method.
【図３】本発明により得られた鋼板の表層近傍組織を示
す図面代用顕微鏡写真である。FIG. 3 is a drawing-substituting micrograph showing a structure near a surface layer of a steel sheet obtained by the present invention.
【図４】従来の製造法により得られた鋼板の表層近傍組
織を示す図面代用顕微鏡写真である。FIG. 4 is a drawing-substituting micrograph showing a structure near a surface layer of a steel sheet obtained by a conventional manufacturing method.
【図５】本発明により得られた鋼板の球状化炭化物組織
を示す図面代用顕微鏡写真である。FIG. 5 is a drawing-substituting micrograph showing a spheroidized carbide structure of a steel sheet obtained according to the present invention.
【図６】従来の製造法により得られた鋼板の球状化炭化
物組織を示す図面代用顕微鏡写真である。FIG. 6 is a drawing-substituting micrograph showing a spheroidized carbide structure of a steel sheet obtained by a conventional manufacturing method.
Ｓｃ：球状化炭化物，Ｌｐ：ラメラーパーライト，Ｄ
ｃ：脱炭層Sc: spheroidized carbide, Lp: lamellar pearlite, D
c: decarburized layer
Claims (1)
鋼冷間圧延鋼帯を、オープンコイル焼鈍炉にて、脱炭雰
囲気中、Ａ1 変態点直下〜Ａ1 変態点−１２０℃の温度
域で、１〜１５時間を要して焼鈍処理することにより、
表面に脱炭層を形成すると共に、脱炭層の内側領域の生
地組織を球状化炭化物組織とすることを特徴とする冷延
特殊鋼表面脱炭鋼帯の製造方法。The method according to claim 1] High carbon steel cold-rolled steel strip having a lamellar pearlite structure, with open coil annealing furnace, during decarburization atmosphere in a temperature range of A 1 transformation point just below to A 1 transformation point -120 ° C., By annealing for 1 to 15 hours,
A method for producing a cold-rolled special steel surface decarburized steel strip, characterized in that a decarburized layer is formed on the surface and the dough structure in the inner region of the decarburized layer is made into a spheroidized carbide structure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34159192A JPH06158157A (en) | 1992-11-27 | 1992-11-27 | Production of cold rolled special steel surface decarburized steel strip |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34159192A JPH06158157A (en) | 1992-11-27 | 1992-11-27 | Production of cold rolled special steel surface decarburized steel strip |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06158157A true JPH06158157A (en) | 1994-06-07 |
Family
ID=18347270
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP34159192A Pending JPH06158157A (en) | 1992-11-27 | 1992-11-27 | Production of cold rolled special steel surface decarburized steel strip |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06158157A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009024472A1 (en) | 2007-08-17 | 2009-02-26 | Thyssenkrupp Steel Ag | Method for producing a surface-decarbonized hot-rolled strip |
-
1992
- 1992-11-27 JP JP34159192A patent/JPH06158157A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009024472A1 (en) | 2007-08-17 | 2009-02-26 | Thyssenkrupp Steel Ag | Method for producing a surface-decarbonized hot-rolled strip |
| US20100319812A1 (en) * | 2007-08-17 | 2010-12-23 | Thyssenkrupp Steel Europe Ag | Method for producing a surface-decarburised hot-rolled strip |
| US8449694B2 (en) | 2007-08-17 | 2013-05-28 | Thyssenkrupp Steel Europe Ag | Method for producing a surface-decarburised hot-rolled strip |
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