JPS6249330B2 - - Google Patents
Info
- Publication number
- JPS6249330B2 JPS6249330B2 JP2551583A JP2551583A JPS6249330B2 JP S6249330 B2 JPS6249330 B2 JP S6249330B2 JP 2551583 A JP2551583 A JP 2551583A JP 2551583 A JP2551583 A JP 2551583A JP S6249330 B2 JPS6249330 B2 JP S6249330B2
- Authority
- JP
- Japan
- Prior art keywords
- gas
- annealing
- furnace
- atmosphere
- annealing furnace
- 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.)
- Expired
Links
- 239000007789 gas Substances 0.000 claims description 76
- 238000000137 annealing Methods 0.000 claims description 55
- 239000012298 atmosphere Substances 0.000 claims description 32
- 229910000831 Steel Inorganic materials 0.000 claims description 19
- 239000010959 steel Substances 0.000 claims description 19
- 238000000034 method Methods 0.000 claims description 13
- 238000010438 heat treatment Methods 0.000 claims description 6
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 19
- 238000005554 pickling Methods 0.000 description 15
- 238000005261 decarburization Methods 0.000 description 8
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 239000003463 adsorbent Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 239000000446 fuel Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- SZVJSHCCFOBDDC-UHFFFAOYSA-N ferrosoferric oxide Chemical compound O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 235000013980 iron oxide Nutrition 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 239000002912 waste gas Substances 0.000 description 2
- 238000005491 wire drawing Methods 0.000 description 2
- 239000002253 acid Substances 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 235000021110 pickles Nutrition 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
- C21D9/54—Furnaces for treating strips or wire
- C21D9/56—Continuous furnaces for strip or wire
- C21D9/561—Continuous furnaces for strip or wire with a controlled atmosphere or vacuum
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Strip Materials And Filament Materials (AREA)
Description
本発明は、スケールが付着したままの熱延鋼線
材あるいは１次伸線された線材の焼鈍方法に関す
るものであり、焼鈍後のスケールのはく離性が優
れたものに焼鈍することができるような焼鈍方法
に関するものである。
従来、溶接用鋼線材を製造する過程で、通常線
材は焼鈍工程を経るが、線材表面にスケールが付
着残留しているものを焼鈍する場合、還元性雰囲
気で処理すると、スケールがち密で、き裂の生じ
難いFe3O4となつて線材はメカニカル・デスケー
ル性が悪くなる。一方、大気などの酸化性雰囲気
ではFe2O3が生成され、このものは酸溶解性が悪
いため、HCl等による強力な酸洗いが必要とな
る。また酸洗いによる鋼材の歩留（酸洗損失）も
低下する。更に酸化性雰囲気の場合、O2が線材
中のＣと反応して線材に脱炭現象が起こる。しか
してN2ガスのような不活性雰囲気の場合でも微
量のCO2やH2Oの存在は防止できない。すなわち
線材コイルの搬入に伴なつて空気や水分が持ち込
まれたり、また供給ガス中に含まれている微量の
O2やH2によりCO2やH2Oが発生する。
これらのCO2，H2Oは線材中のＣと反応するの
で線材に脱炭を起こす。
一方、スケールの付着していない状態で鋼線材
を焼鈍するには、焼鈍前に酸洗いすることが必要
であるが、この場合の酸洗いは作業がはん雑であ
り、また能率が低い。更に焼鈍時では、浸炭も脱
炭もしないように、雰囲気中のCO，CO2濃度を
管理する必要がある。しかし、焼鈍の際に線材か
ら発生するCO，CO2によつて雰囲気濃度が変化
するため、該濃度の管理が難しく、しかも濃度変
化に対応してガス発生器よりのガス導入量を増加
して濃度を所定値にするように濃度を管理するの
で、導入ガスの使用量も多くする必要がある。
本発明の目的は、スケールを付着したままの熱
延鋼線材あるいは１次伸線後の線材を焼鈍する方
法において、従来方法における上記の欠点を解消
して、焼鈍後のスケールのはく離性が優れた焼鈍
材に焼鈍することができる該鋼線材の焼鈍方法を
提供することにあり、他の目的は、N2ガス雰囲
気により該鋼線材を焼鈍する際に発生する脱炭現
象を防止すること可能にした該鋼線材の焼鈍方法
を提供することにある。
すなわち、本発明の要旨は次に示すとおりのも
のである。
表面にスケールの付着した熱延鋼線材コイルあ
るいは１次伸線後の線材を連続式焼鈍炉で焼鈍す
るに際して、該焼鈍炉の加熱帯中で該鋼線材が
570℃以下に加熱されている箇所に、該焼鈍炉の
入口側に向けてO2を0.5〜0.9vol.％含有するN2ガ
スを導入させるとともに、該焼鈍炉入口側から雰
囲気ガスを抜き出してこのガスを該焼鈍炉出口側
から再び該焼鈍炉内に導入し、かつ該焼鈍炉の出
口側より炉内雰囲気ガスの一部を抽出し、この排
ガスを大気と共にガス精製器を通してこれらガス
中のCO2及びH2Oを除いた後、これら精製ガスを
該焼鈍炉の加熱帯中の前記箇所に導入し、以上の
操作により該焼鈍炉雰囲気を0.002〜0.3vol.％の
O2を含むＮ雰囲気に維持させ、この雰囲気によ
つて焼鈍を行なうことを特徴とする、焼鈍後のス
ケールはく離性が優れた鋼線材の焼鈍方法。
以下、本発明について詳細に説明する。
鋼材のスケール層には、その内層より外層にわ
たつて順次FeO，Fe3O4，Fe2O3という形の鉄酸
化物が存在している。このうちFe2O4層はち密で
かつ破壊強度が他のものより非常に大であるた
め、メカニカル・デスケーリング性が最も悪い。
一方Fe2O3は、破壊強度が比較的小さいため、メ
カニカル・デスケール性が良好であり、したがつ
てき裂を生じやすいので酸洗性も良好である。
本発明者は、表面にスケールを残留している熱
延鋼線材を焼鈍する方法について焼鈍後のスケー
ルのはく離性を優れたものにすることができる焼
鈍条件を種々研究を重ねたところ、0.3vol.3％以
下のO2を含むN2ガス雰囲気中で焼鈍することに
よつて、スケール内層中のFe3O4は、Fe2O3とな
つてメカニカル・デスケーリング法によるデスケ
ール性が良好な鉄酸化物となることが見い出され
た。
本発明は、この知見から出発している。本発明
は表面にスケールが残留したままの熱延鋼線材の
コイルを連続式焼鈍炉において、0.002〜0.3vol.
％のO2を含むN2雰囲気中で焼鈍するのである
が、このようにN2雰囲気中のO2濃度を限定する
理由は、次のとおりである。
雰囲気のN2ガスに少量のO2を添加すると、上
述のようにスケール中のFe3O4をメカニカル・デ
スケール性の良好なFe2O3に変えることができる
のであるが、O2濃度が0.002vol.％より少ない
と、スケール中のメタリツクのFeが生成してメ
カニカル・デスケーリング効果が少なく、他方
O2濃度が0.3vol.％を超えると、O2量が多くなり
過ぎて線材中のＣと反応し脱炭現象が生じる。あ
るいはFe2O3が鉄地に食い込んだ形で生成するた
めH2SO4酸洗では不溶のスケールが生じ、あるい
はHCl酸洗においても酸洗時間を長くする必要が
ある。更に、過剰のO2によりスケール量が増加
するので酸洗歩留も悪くなる。
第１図は、Ｎ雰囲気中のO2濃度（vol.％）が焼
鈍前の鋼線材のスケール量に対する焼鈍後のスケ
ール量の増加率（％）に及ぼす影響を示す図表で
ある。第１図から明らかなように、O2濃度が小
さくなれば少ない程、スケールの増加は少ない
が、このような場合、操炉上の管理が難しく、ま
た上述のようにスケール中にメタリツクFeが生
じてメカニカル・デスケール性が悪くなる。一方
O2濃度が大きくなると難溶性のスケール
（Fe2O3）が増加して酸洗能率や酸洗歩留の低下を
来たす。
次に本発明における焼鈍炉内雰囲気の調整につ
いて述べる。
本発明において規定したように炉内雰囲気を
O2を0.002〜0.3vol.％含むN2ガスの雰囲気に維持
する手段としては、ガス発生器によつて燃料と空
気を必要な混合比で燃焼させ、生成したガス
（O2，H2O，COを含み残部はN2）よりH2O，CO2
を吸着剤によつて除いて上記のO2濃度のN2ガス
として、これを焼鈍炉内に供給すればよいように
考えられるが、O2濃度が0.5％（vol.）以下にな
ると、完全燃焼しているとはいえ微量のCO，H2
が生成している。このH2は炉内の微量O2と反応
してH2Oとなり、炉内の露点を上げて粒界酸化を
発生させ脱炭を起すため、H2の存在は絶対抑え
える必要がある。そのため、本発明では、ガス発
生器よりのガスはO2濃度を高めにしてN2＋0.5〜
0.9％O2とする。このガスを炉内に投入すると、
そのO2は線材と反応するため炉内雰囲気のO2は
次第に低下してやがて０％となる。
そこで炉内雰囲気のO2を0.002％以上0.3％以下
に調整するために、炉外精製器を通して内蔵の吸
着剤によりH2Oを除去した大気を炉内に供給す
る。これら発生器及び精製器の両方から炉内に併
せて導入されるガスのO2濃度は炉内雰囲気ガス
よりも高いため、これらガスを線材が600℃以上
にある箇所導入すると、線材のスケールはFe2O3
が多いものとなり、しかも鉄地に食い込んだ状態
になるためメカニカル・デスケールでもはく離せ
ず、またH2SO4では溶解できない。更にHClで溶
解しようとすると、通常以上の時間が必要とな
る。
そこで上記ガスの導入を加熱帯中、線材の温度
の低いところ、すなわち570℃以下にあるところ
で行なつたところ、線材スケールにはFe2O3の生
成が少なく、したがつて酸洗も問題なく処理でき
ることが分つた。
なお、上記のように大気よりの空気で炉内雰囲
気を調整する代りに、ガス発生器において燃焼ガ
スをN2＋0.5〜0.9％O2よりもO2量を多くし、例
えばN2＋0.9〜1.3％O2としてこれを導入すること
によつても炉内のO2を管理することは可能であ
るが、燃料のカロリーの変動により高めのO2濃
度、例えば1.3％O2付近のガスを既に述べた570℃
以下の帯域導入しても、Fe2O3の多いスケールと
なるので、発生器よりのO2濃度は低目すなわち
N2＋0.5〜0.9％O2とする方が効果的である。
しかして、炉内に連続的に送り込まれた線材コ
イルは、進行されて高温になるに従い雰囲気の
O2と反応してCO2を発生するが、このCO2が次第
に増えると線材は脱炭を助長されるため、この
CO2を含む焼鈍廃ガスは炉外に放出しなければな
らない。しかし、この場合N2ガスも放出される
ことになるので、不活性ガスを製造するコストの
上昇につながる。
そこで本発明では、この放出すべきガスを放出
後、ガス精製器に吸引して内蔵の吸着剤によつて
CO2を除去し、残部のN2を再度炉内に送り込むの
である。このようにしてガスコストの低減と省エ
ネルギーが計れる。
なお、上記精製器においては、炉内に線材コイ
ルに付着して持ち込まれたH2Oも除去する能力が
あつて、上記廃ガス中のCO2の除去と同時に炉内
中のH2Oも除去するので、炉内雰囲気の露点を下
げ、粒界酸化の発生を防止する効果も得られる。
第２図は、本発明による連続焼鈍炉の雰囲気ガ
スの循環系統を示すものであり、第３図は、同焼
鈍炉において線材が移動するにしたがつて推移し
てゆく線材の温度を示すものである。
第２図について説明すると、ガス発生器におい
て燃料を必要な混合比で空気で燃焼して0.5〜0.9
％のO2を含むN2ガスを製造し、加熱帯内で線材
温度が570℃以下にある箇所に設けたガス導入口
ａから、前記ガスを導入するとともに大気をガス
精製器に通してH2Oを除いてから前記線材温度の
箇所に別に設けた導入口ｂより炉内に導入する。
これら導入ガスの供給量を調整して均熱帯内雰囲
気をN2＋0.002〜0.3％O2となるようにする。
次いで炉内雰囲気を炉入口側に設けた排出口ｃ
から炉外に抜き出し、図示の流れのようにフアン
を介して炉出口側に設けた導入口ｄから炉の冷却
帯に再供給する。以上のようにして雰囲気ガスは
図示の方向で循環される。また、冷却帯に設けた
排出口ｅより、焼鈍で生成したガスの一部を抜き
出してガス精製器に導いて排ガス中のH2O，CO2
を除去し、既記の導入口ｂから再び導入する。
以上の雰囲気ガスの循環方式によつて、O2濃
度が比較的高いN2ガスは温度が低い線材と接触
し、O2濃度が薄くなつたN2ガスが高温状態にあ
る線材と接触することになる。したがつて線材の
脱炭を防止することができるとともに脱スケール
を有効に行なうことができる。更に使用ガスによ
る炉内壁や線材の汚染も生じない。
以下、本発明の実施例について述べる。
The present invention relates to a method for annealing a hot rolled steel wire rod with scale attached thereto or a wire rod that has been primarily drawn, and is an annealing method that can be annealed to a wire rod with excellent scale peelability after annealing. It is about the method. Conventionally, in the process of manufacturing steel wire rods for welding, the wire rods usually go through an annealing process, but when annealing wire rods with scale attached and remaining on the surface, if treated in a reducing atmosphere, the scales are dense and hard. Since Fe 3 O 4 is difficult to cause cracks, the mechanical descaling properties of the wire are poor. On the other hand, in an oxidizing atmosphere such as the air, Fe 2 O 3 is generated, and since this substance has poor acid solubility, strong pickling with HCl or the like is required. In addition, the yield of steel materials (pickling loss) due to pickling also decreases. Furthermore, in the case of an oxidizing atmosphere, O 2 reacts with C in the wire, causing a decarburization phenomenon in the wire. However, even in the case of an inert atmosphere such as N 2 gas, the presence of trace amounts of CO 2 and H 2 O cannot be prevented. In other words, air and moisture may be brought in when the wire coils are brought in, and trace amounts of water contained in the supplied gas may be introduced.
O 2 and H 2 generate CO 2 and H 2 O. These CO 2 and H 2 O react with C in the wire, causing decarburization of the wire. On the other hand, in order to anneal the steel wire in a state where no scale is attached, it is necessary to pickle the wire before annealing, but pickling in this case is complicated and has low efficiency. Furthermore, during annealing, it is necessary to control the CO and CO 2 concentrations in the atmosphere so that neither carburization nor decarburization occurs. However, since the atmospheric concentration changes due to CO and CO 2 generated from the wire during annealing, it is difficult to control the concentration, and the amount of gas introduced from the gas generator must be increased in response to the concentration change. Since the concentration is controlled to a predetermined value, it is necessary to increase the amount of introduced gas. The purpose of the present invention is to solve the above-mentioned drawbacks of the conventional method in a method of annealing hot-rolled steel wire rods with scale still attached or wire rods after primary wire drawing, and to achieve excellent peeling properties of scales after annealing. The purpose is to provide a method for annealing the steel wire rod that can be annealed into an annealed material, and another purpose is to prevent the decarburization phenomenon that occurs when the steel wire rod is annealed in a N2 gas atmosphere. An object of the present invention is to provide a method for annealing the steel wire rod. That is, the gist of the present invention is as follows. When a hot-rolled steel wire coil with scale attached to its surface or a wire rod after primary wire drawing is annealed in a continuous annealing furnace, the steel wire rod is heated in the heating zone of the annealing furnace.
N 2 gas containing 0.5 to 0.9 vol.% O 2 is introduced toward the inlet side of the annealing furnace into the area heated to 570°C or less, and atmospheric gas is extracted from the annealing furnace inlet side. This gas is introduced into the annealing furnace again from the annealing furnace outlet side, a part of the furnace atmosphere gas is extracted from the annealing furnace outlet side, and this exhaust gas is passed through a gas purifier together with the atmosphere to remove the After removing CO 2 and H 2 O, these purified gases are introduced into the heating zone of the annealing furnace.
A method for annealing a steel wire rod with excellent scale removal properties after annealing, characterized by maintaining a N atmosphere containing O 2 and performing annealing in this atmosphere. The present invention will be explained in detail below. In the scale layer of steel materials, iron oxides in the form of FeO, Fe 3 O 4 and Fe 2 O 3 exist sequentially from the inner layer to the outer layer. Among these, the Fe 2 O 4 layer is dense and has much higher breaking strength than the others, so it has the worst mechanical descaling properties.
On the other hand, Fe 2 O 3 has a relatively low breaking strength, so it has good mechanical descaling properties, and therefore, it easily cracks, so it also has good pickling properties. The present inventor conducted various studies on annealing conditions that can improve the peeling properties of scale after annealing regarding a method of annealing hot rolled steel wire rods with scale remaining on the surface, and found that 0.3 vol. By annealing in a N2 gas atmosphere containing .3% or less O2 , Fe3O4 in the inner layer of the scale becomes Fe2O3 , which has good descalability by mechanical descaling . It was discovered that it becomes iron oxide. The present invention is based on this knowledge. In the present invention, a coil of hot-rolled steel wire with scale remaining on its surface is heated in a continuous annealing furnace to a temperature of 0.002 to 0.3 vol.
The reason for limiting the O 2 concentration in the N 2 atmosphere in this way is as follows. By adding a small amount of O 2 to the N 2 gas in the atmosphere, Fe 3 O 4 in the scale can be changed to Fe 2 O 3 with good mechanical descaling properties as described above, but the O 2 concentration is If it is less than 0.002vol.%, metallic Fe in the scale will be generated and the mechanical descaling effect will be small.
When the O 2 concentration exceeds 0.3 vol.%, the amount of O 2 becomes too large and reacts with C in the wire, causing a decarburization phenomenon. Alternatively, Fe 2 O 3 is generated in a form that bites into the iron base, so H 2 SO 4 pickling results in insoluble scale, or HCl pickling also requires a longer pickling time. Furthermore, the amount of scale increases due to excess O 2 , resulting in poor pickling yield. FIG. 1 is a chart showing the influence of the O 2 concentration (vol.%) in the N atmosphere on the increase rate (%) of the scale amount after annealing relative to the scale amount of the steel wire rod before annealing. As is clear from Fig. 1, the smaller the O 2 concentration, the less the scale increases. However, in such cases, it is difficult to manage the reactor operation, and as mentioned above, metallic Fe is present in the scale. This results in poor mechanical descaling. on the other hand
As the O 2 concentration increases, poorly soluble scale (Fe 2 O 3 ) increases, resulting in a decrease in pickling efficiency and pickling yield. Next, the adjustment of the atmosphere inside the annealing furnace in the present invention will be described. The atmosphere inside the furnace is maintained as specified in the present invention.
As a means to maintain an atmosphere of N 2 gas containing 0.002 to 0.3 vol.% O 2 , fuel and air are combusted at the required mixing ratio using a gas generator, and the generated gas (O 2 , H 2 O , CO and the remainder is N 2 ), H 2 O, CO 2
It may be possible to remove this with an adsorbent and supply it as N 2 gas with the above O 2 concentration into the annealing furnace, but if the O 2 concentration becomes 0.5% (vol.) or less, Even though it is burning, a small amount of CO, H 2
is being generated. This H 2 reacts with a small amount of O 2 in the furnace to become H 2 O, raising the dew point in the furnace and causing grain boundary oxidation and decarburization, so the presence of H 2 must be absolutely suppressed. Therefore, in the present invention, the gas from the gas generator has a high O 2 concentration and is N 2 +0.5~
Set to 0.9% O2 . When this gas is put into the furnace,
Since the O 2 reacts with the wire, the O 2 in the furnace atmosphere gradually decreases and eventually reaches 0%. Therefore, in order to adjust the O 2 content in the furnace atmosphere to 0.002% or more and 0.3% or less, air from which H 2 O has been removed by a built-in adsorbent is supplied to the furnace through an external purifier. The O 2 concentration of the gases introduced into the furnace from both the generator and purifier is higher than the atmospheric gas in the furnace, so if these gases are introduced at a point where the wire is at a temperature of 600°C or higher, the scale of the wire will be reduced. Fe2O3 _
Furthermore, since it is embedded in the iron base, it cannot be removed even with mechanical descaling, and it cannot be dissolved with H 2 SO 4 . Furthermore, if you try to dissolve it with HCl, it will take more time than usual. Therefore, when the above gas was introduced into the heating zone where the temperature of the wire was low, i.e. below 570°C, there was little Fe 2 O 3 formed on the wire scale, so pickling was no problem. I found out that it can be handled. In addition, instead of adjusting the atmosphere in the furnace with air from the atmosphere as described above, the amount of O 2 is larger than N 2 + 0.5 to 0.9% O 2 in the combustion gas in the gas generator, for example, N 2 + 0. It is possible to manage O 2 in the furnace by introducing it as .9 to 1.3% O 2 , but due to fluctuations in the calorie of the fuel, higher O 2 concentrations, e.g. around 1.3% O 2 The gas of 570℃ already mentioned
Even if the following bands are introduced, the scale will contain a lot of Fe 2 O 3 , so the O 2 concentration from the generator will be low, i.e.
It is more effective to use N 2 +0.5 to 0.9% O 2 . As the wire coil is continuously fed into the furnace, the atmosphere changes as it progresses and becomes hotter.
It reacts with O 2 and generates CO 2 , but as this CO 2 gradually increases, decarburization of the wire is promoted, so this
Annealing waste gas containing CO 2 must be discharged outside the furnace. However, in this case, N2 gas will also be released, leading to an increase in the cost of producing inert gas. Therefore, in the present invention, after the gas to be released is released, it is sucked into the gas purifier and is absorbed by the built-in adsorbent.
The CO 2 is removed and the remaining N 2 is sent back into the furnace. In this way, gas costs can be reduced and energy can be saved. Note that the purifier has the ability to remove H 2 O that has adhered to the wire coil and is brought into the furnace, and at the same time removes the CO 2 in the waste gas, it also removes the H 2 O in the furnace. Since it is removed, it is also possible to lower the dew point of the furnace atmosphere and prevent the occurrence of grain boundary oxidation. Figure 2 shows the atmospheric gas circulation system of the continuous annealing furnace according to the present invention, and Figure 3 shows the temperature of the wire changing as it moves in the annealing furnace. It is. To explain Figure 2, fuel is combusted with air in a gas generator at the required mixing ratio of 0.5 to 0.9.
N 2 gas containing % O 2 is produced, and the gas is introduced from the gas inlet a provided at a location in the heating zone where the wire temperature is below 570°C, and the atmosphere is passed through a gas purifier to produce H 2 After removing O, the wire is introduced into the furnace through a separate inlet b provided at the wire temperature.
The supply amount of these introduced gases is adjusted so that the atmosphere in the soaking zone becomes N 2 +0.002 to 0.3% O 2 . Next, the atmosphere inside the furnace is removed from the exhaust port c provided on the furnace inlet side.
It is extracted from the furnace and re-supplied to the cooling zone of the furnace from the inlet d provided on the furnace exit side via a fan as shown in the flowchart. As described above, the atmospheric gas is circulated in the direction shown. In addition, a part of the gas generated during annealing is extracted from the exhaust port e provided in the cooling zone and guided to a gas purifier to remove H 2 O and CO 2 from the exhaust gas.
is removed and reintroduced through the previously described introduction port b. With the above atmospheric gas circulation method, N 2 gas with a relatively high O 2 concentration comes into contact with the wire rod at a low temperature, and N 2 gas with a low O 2 concentration comes into contact with the wire rod at a high temperature. become. Therefore, decarburization of the wire can be prevented and descaling can be carried out effectively. Furthermore, the furnace inner walls and wire rods are not contaminated by the gas used. Examples of the present invention will be described below.
【表】
残部はFeであり、線径5.5〜2.5mmφの線材であ
る。焼鈍炉雰囲気ガスについて述べれば、ガス発
生器からのガス導入口の位置ａは炉内温度200〜
300℃の位置で、ガス投入量は70〜140Nm3／Hr、
ガス組成は、O20.5〜0.9Vol％，CO20.2〜0.4Vol
％，CO0.1Vol％、残N2であり、炉内ガス排出
口ｃから精製器へのガス流入量は70Nm3／Hrであ
るからガス流入比率は70/70〜140＝１〜２とな
り、炉内ガス排出口におけるガス組成は、
O20.002〜0.3Vol％，CO20.2〜0.4Vol％，CO
0.1Vol％、残N2であつて炉内の平均ガス組成と同
じである。
第１表に示す成分の鋼種からなる線材Ａについ
て６例、同Ｂについて５例それぞれ第２表に示す
焼鈍条件によつてO2含有N2ガスの雰囲気中で焼
鈍した。第２表中の炉内O2％は、各例いずれも
第２図について説明した雰囲気ガス循環方式によ
つて得られたものである。
次いで各例によつて得られた焼鈍線材それぞれ
についてスケールの増加量を測定した後、デスケ
ーリング試験をメカニカル・デスケーリングと酸
洗とについて行ない、デスケーリング性を評価し
た。
以上の試験結果は第２表に示される。[Table] The remainder is Fe, and the wire rod has a wire diameter of 5.5 to 2.5 mmφ. Regarding the annealing furnace atmospheric gas, the position a of the gas inlet from the gas generator is set at a temperature of 200~200°C.
At a temperature of 300℃, the gas input amount is 70 to 140Nm 3 /Hr,
Gas composition: O 2 0.5-0.9Vol%, CO 2 0.2-0.4Vol
%, CO0.1Vol%, residual N2 , and the amount of gas flowing into the purifier from the furnace gas outlet c is 70Nm 3 /Hr, so the gas inflow ratio is 70/70~140=1~2, The gas composition at the furnace gas outlet is:
O 2 0.002~0.3Vol%, CO 2 0.2~0.4Vol%, CO
0.1Vol%, residual N2 , which is the same as the average gas composition in the furnace. Six cases of wire A and five cases of wire rod B, each made of a steel type with the components shown in Table 1, were annealed in an atmosphere of O 2 -containing N 2 gas under the annealing conditions shown in Table 2. The in-furnace O 2 % in Table 2 was obtained in each case by the atmospheric gas circulation method explained in connection with FIG. Next, after measuring the amount of increase in scale for each of the annealed wire rods obtained in each example, a descaling test was conducted for mechanical descaling and pickling to evaluate descaling properties. The above test results are shown in Table 2.
【表】
第２表から明らかなように、本発明において規
定した焼鈍雰囲気のO2濃度の上限値を超えてい
る比較例の７，８，９によるものは、スケールの
増加が大きいため、酸洗歩留が低いうえ酸洗性が
悪い。また本発明のO2濃度の下限値より低い比
較例の10，11によるものは、メカニカル・デスケ
ール性が不良である。
これに対し、本発明の実施例によるものは、い
ずれもデスケール性がより優れており、また酸洗
歩留も高くなつている。したがつて本発明によれ
ば、スケールを付着したままの熱延鋼線材からス
ケールのはく離が優れた焼鈍材が得られることは
明らかである。[Table] As is clear from Table 2, Comparative Examples 7, 8, and 9, in which the O 2 concentration in the annealing atmosphere exceeds the upper limit specified in the present invention, have a large increase in scale, so Washing yield is low and pickling properties are poor. Moreover, those according to Comparative Examples 10 and 11 whose O 2 concentration is lower than the lower limit of the present invention have poor mechanical descaling properties. On the other hand, all of the samples according to the examples of the present invention have better descaling properties and higher pickling yields. Therefore, it is clear that according to the present invention, an annealed material with excellent scale removal can be obtained from a hot-rolled steel wire with scale still attached.
第１図はN2焼鈍雰囲気中のO2濃度（vol.％）と
焼鈍後のスケール増加率（wt.％）との関係を示
す図表であり、第２図は本発明における連続焼鈍
炉雰囲気ガスの循環系統を示す図であり、第３図
は同じく該焼鈍炉における線材の温度を示す図表
である。
ａ……ガス発生器からのガス導入口、ｂ……ガ
ス精製器からのガス導入口、ｃ……炉内ガス排出
口、ｄ……排ガス導入口、ｅ……炉内ガス排出
口、Ｆ……フアン。
Fig. 1 is a chart showing the relationship between the O 2 concentration (vol.%) in the N 2 annealing atmosphere and the scale increase rate (wt.%) after annealing, and Fig. 2 shows the continuous annealing furnace atmosphere in the present invention. FIG. 3 is a diagram showing a gas circulation system, and FIG. 3 is a chart showing the temperature of the wire in the annealing furnace. a... Gas inlet from the gas generator, b... Gas inlet from the gas purifier, c... Furnace gas outlet, d... Exhaust gas inlet, e... Furnace gas outlet, F ...Juan.
Claims (1)
あるいは１次伸線された線材を連続式焼鈍炉で焼
鈍するに際して、該焼鈍炉の加熱帯中で該鋼線材
が570℃以下に加熱されている箇所に、該焼鈍炉
の入口側に向けてO2を0.5〜0.9vol.％含有するN2
ガスを導入させるとともに、該焼鈍炉入口側から
雰囲気ガスを抜き出してこのガスを該焼鈍炉出口
側から再び該焼鈍炉内に導入し、かつ該焼鈍炉の
出口側より炉内雰囲気ガスの一部を抽出し、この
排ガスを大気と共にガス精製器を通してこれらガ
ス中のCO2及びH2Oを除いた後、これら精製ガス
を該焼鈍炉の加熱帯中の前記箇所に導入し、以上
の操作によつて該焼鈍雰囲気を0.002〜0.3vol.％
のO2を含むN2雰囲気に維持させ、この雰囲気に
よつて焼鈍を行なうことを特徴とする焼鈍後のス
ケールはく離性が優れた鋼線材の焼鈍方法。1. When a hot-rolled steel wire coil with scale attached to the surface or a wire rod that has been primarily drawn is annealed in a continuous annealing furnace, the steel wire rod is heated to 570°C or less in the heating zone of the annealing furnace. N 2 containing 0.5 to 0.9 vol.% O 2 toward the inlet side of the annealing furnace.
At the same time as introducing gas, atmospheric gas is extracted from the annealing furnace inlet side, and this gas is introduced into the annealing furnace again from the annealing furnace outlet side, and part of the furnace atmospheric gas is extracted from the annealing furnace exit side. After extracting this exhaust gas along with the atmosphere through a gas purifier to remove CO 2 and H 2 O from these gases, these purified gases are introduced into the above-mentioned location in the heating zone of the annealing furnace, and the above operations are carried out. Therefore, the annealing atmosphere should be 0.002 to 0.3 vol.%.
A method for annealing a steel wire rod with excellent scale removal properties after annealing, characterized by maintaining an N 2 atmosphere containing O 2 and annealing in this atmosphere.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2551583A JPS59153842A (en) | 1983-02-19 | 1983-02-19 | Production of steel wire rod having excellent scale detachability after annealing |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2551583A JPS59153842A (en) | 1983-02-19 | 1983-02-19 | Production of steel wire rod having excellent scale detachability after annealing |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59153842A JPS59153842A (en) | 1984-09-01 |
| JPS6249330B2 true JPS6249330B2 (en) | 1987-10-19 |
Family
ID=12168191
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2551583A Granted JPS59153842A (en) | 1983-02-19 | 1983-02-19 | Production of steel wire rod having excellent scale detachability after annealing |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59153842A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004009856A1 (en) * | 2002-07-22 | 2004-01-29 | Suzuki Metal Industry Co.,Ltd | Process for producing oil tempered wire |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2649124A1 (en) * | 1989-07-03 | 1991-01-04 | Air Liquide | PROCESS FOR THE HEAT TREATMENT OF METALS UNDER ATMOSPHERE |
-
1983
- 1983-02-19 JP JP2551583A patent/JPS59153842A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004009856A1 (en) * | 2002-07-22 | 2004-01-29 | Suzuki Metal Industry Co.,Ltd | Process for producing oil tempered wire |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59153842A (en) | 1984-09-01 |
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