JPH03274225A - Production of wide flange shape with thin-walled web - Google Patents
Production of wide flange shape with thin-walled webInfo
- Publication number
- JPH03274225A JPH03274225A JP7623690A JP7623690A JPH03274225A JP H03274225 A JPH03274225 A JP H03274225A JP 7623690 A JP7623690 A JP 7623690A JP 7623690 A JP7623690 A JP 7623690A JP H03274225 A JPH03274225 A JP H03274225A
- Authority
- JP
- Japan
- Prior art keywords
- web
- flange
- cooling
- water cooling
- rolling
- 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.)
- Granted
Links
- 238000004519 manufacturing process Methods 0.000 title claims description 11
- 238000001816 cooling Methods 0.000 claims abstract description 106
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 52
- 238000005096 rolling process Methods 0.000 claims abstract description 43
- 238000000034 method Methods 0.000 claims abstract description 24
- 239000002344 surface layer Substances 0.000 claims abstract description 16
- 229910000831 Steel Inorganic materials 0.000 claims description 27
- 239000010959 steel Substances 0.000 claims description 27
- 230000008569 process Effects 0.000 claims description 10
- 230000008646 thermal stress Effects 0.000 claims description 8
- 238000003303 reheating Methods 0.000 claims description 5
- 239000000498 cooling water Substances 0.000 claims description 3
- 229910000859 α-Fe Inorganic materials 0.000 abstract description 3
- 229910001566 austenite Inorganic materials 0.000 abstract description 2
- 230000001133 acceleration Effects 0.000 abstract 1
- 238000001556 precipitation Methods 0.000 abstract 1
- 238000007670 refining Methods 0.000 abstract 1
- 230000035882 stress Effects 0.000 description 20
- 230000007423 decrease Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000007796 conventional method Methods 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 238000005098 hot rolling Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000005275 alloying Methods 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 229910001562 pearlite Inorganic materials 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
Abstract
Description
【発明の詳細な説明】
［産業上の利用分野コ
フランジ厚に対しウェブ厚が薄い薄肉ウェブＨ形鋼を熱
間圧延によって製造する際に、ウェブ波発生を防止する
とともに強制冷却によって生じる冷却面の硬度上昇を抑
制する薄肉ウェブＨ形鋼の製造方法に関するものである
。Detailed Description of the Invention [Industrial Field of Application] When manufacturing a thin web H section steel with a thinner web thickness than the coflange thickness by hot rolling, it is possible to prevent the generation of web waves and reduce the cooling surface caused by forced cooling. The present invention relates to a method for manufacturing a thin web H-section steel that suppresses increase in hardness.
［従来の技術及び発明が解決しようとする課題］単位長
さ当りの重量に対して断面係数か大きく、経済性の優れ
た薄肉ウェブＨ形鋼は、従来は溶接によるビルドアップ
Ｈ形鋼が主流を占めていたが、近時は圧延による各種の
製造手段が提案されるようになった。即ち、圧延による
薄肉ウェブＨ形鋼の製造方法で最も重要な課題はウェブ
波の発生をいかに解決するかであったが、近時に至り各
種の実用的な対策が提案されている。薄肉ウェブＨ形鋼
のウェブ波とは周知のとおり、フランジとウェブの冷却
過程における温度差に起因する残留応力によって、ウェ
ブの座屈限界を超える圧縮内部応力がウェブに発生し、
これがウェブに波状の形状不良として現れるものである
。本願出願人はウェブ波を防止する手段として、先に特
開平１−２０５０２８号公報の技術を提案した。この提
案の要旨は、強制冷却中にウェブ波が発生しない水冷時
間の上限もしくは水冷直後のフランジとウェブの温度差
の下限と、強制冷却後常温に至るまでのウェブの熱応力
がウェブの座屈応力以下となる水冷時間の下限もしくは
水冷直後のフランジとウェブの温度差の上限をＨ形鋼の
サイズおよび冷却水量密度毎に予め定めておき、この上
下限範囲内でフランジの強制冷却を行い、水冷終了時の
フランジとウェブの温度差が一定範囲内になるようにす
る手段であった。[Prior art and problems to be solved by the invention] Conventionally, build-up H-section steels by welding have been mainstream as thin-walled web H-section steels, which have a large section modulus relative to the weight per unit length and are highly economical. However, recently various manufacturing methods using rolling have been proposed. That is, the most important issue in the method of manufacturing thin-walled web H-section steel by rolling has been how to solve the problem of web waves, but recently various practical countermeasures have been proposed. As is well known, web waves in thin-walled H-beam steel are caused by compressive internal stress that exceeds the web's buckling limit due to residual stress caused by the temperature difference during the cooling process between the flange and the web.
This appears as a wavy shape defect on the web. The applicant of the present application previously proposed the technique disclosed in Japanese Unexamined Patent Publication No. 1-205028 as a means for preventing web waves. The gist of this proposal is to determine the upper limit of the water cooling time during which web waves do not occur during forced cooling, or the lower limit of the temperature difference between the flange and the web immediately after water cooling, and the thermal stress of the web until it reaches room temperature after forced cooling, which causes web buckling. The lower limit of the water cooling time at which the stress is below or the upper limit of the temperature difference between the flange and the web immediately after water cooling is determined in advance for each size of H-beam steel and cooling water flow density, and the flange is forcedly cooled within this upper and lower limit range. This was a means to ensure that the temperature difference between the flange and the web at the end of water cooling was within a certain range.
この特開平１−２０５０２８号技術によれは冷却制御の
みでウェブ波の無い薄肉ウェブＨ形鋼を経済的に製造す
ることが可能となったが、強制冷却によってフランジに
焼きが入り、フランジ表面硬度が過度に上昇する場合が
あることが分かった。一般のＨ形鋼でも表面硬度が高す
ぎると、孔明は等の加工が困難になり、また焼きが入る
と降伏点（ＹＰ）、引張強さ（ＴＳ）が極端に高くなる
とともに伸びが低下して所定の材質を満足できないこと
が知られているが、フランジ冷却による薄肉ウェブＨ形
鋼の製造法では特に表面硬度の上昇が顕著に表れること
が分かった。The technology of JP-A-1-205028 made it possible to economically produce thin web H-section steel without web waves by only cooling control, but the forced cooling caused the flange to become hardened and the flange surface hardness. It was found that there are cases where the amount increases excessively. Even with ordinary H-shaped steel, if the surface hardness is too high, it becomes difficult to process holes, etc., and when hardened, the yield point (YP) and tensile strength (TS) become extremely high, and the elongation decreases. Although it is known that the specified material quality cannot be satisfied, it has been found that the method of manufacturing thin-walled web H-section steel by flange cooling results in a particularly remarkable increase in surface hardness.
フランジ冷却による熱間圧延法によって薄肉ウェブＨ形
鋼を製造するに際し、ウェブ波の防止と同時にフランジ
表面の硬度上昇を抑制する新規な製造方法を提供するも
のである。The present invention provides a new manufacturing method that prevents web waves and at the same time suppresses an increase in hardness of the flange surface when manufacturing a thin web H-section steel by a hot rolling method using flange cooling.
［課題を解決するための手段・作用コ
まず、本出願人の先願発明、特開平１−２０５０２８号
公報技術と共通するＨ形鋼のウェブ波に関する基本的な
メカニズム、即ちフランジの冷却条件、冷却後の時間経
過がフランジおよびウェブの温度、さらにはウェブ応力
等にどのように影響するかについて述べる。第４図（ａ
）は仕上げ圧延後のＨ形鋼の空冷および水冷における冷
却曲線の例を示し、第４図（ｂ） は第４図（ａ）の温
度変化に対応するウェブの熱応力の変化を示したもので
ある。横軸はウェブ幅方向中央部の温度であり、横軸右
方向は時間の経過とともに高温から低温へ推移する状態
を示す。曲線１１は空冷の場合のフランジ冷却曲線、曲
線１２〜１４はウェブ温度がＤであった時点からフラン
ジ水冷を開始した時のフランジの冷却曲線であり、１２
は短時間水冷（水冷終了が温度Ｅまで）、１４は長時間
水冷（水冷終了温度Ｇまで）、１３は両者中間の水冷時
間（水冷終了が温度Ｆまで）で冷却した場合の各フラン
ジの冷却曲線を示す。直線１５はウェブの冷却曲線であ
るが、ウェブに対しては強制冷却を施さないので空冷・
水冷共通となっている。′ｊ８４図の曲線１６〜１９は
前記の各冷却曲線１１〜１４に対応するウェブの熱応力
推移を示す。また、図中の曲線２０．はウェブの座屈応
力を示し、高温度になるほど小さな値となる。ところで
、ウェブ波は前記したようにウェブの座屈限界を越える
圧縮内部応力がウェブに発生するから、第４図の空冷の
場合の熱応力１６は温度低下につれて圧縮応力が増大し
、点二において座屈応力２０に達し、ウェブ波が発生す
ることになる。フランジ水冷材の熱応力を示す曲線１７
〜１９で共通していることは、水冷中にフランジとウェ
ブの温度差が小さくなるに従い圧縮応力が増大するが、
水冷を終了すると一旦引張り側へ変化した後、再び圧縮
側へ変化する。これは水冷により縮小されたフランジと
ウェブの温度差が水冷後−旦拡大し、縮小するためであ
る。水冷中のウェブの圧縮応力は点ト、へ、ホで示すよ
うに、水冷時間が長いほど大きく、逆に常温の圧縮応力
は点ヌ、す、チで示すように水冷時間が長いほど小さく
なる。上記の短・中・長・の各水冷時間条件のうちで冷
却時間の長い応力推移曲線１９の水冷中の応力は点ルで
座屈応力２０に達しており、水冷中にウェブ波が発生す
る。[Means and effects for solving the problem] First, we will discuss the basic mechanism regarding the web waves of H-section steel, which is common to the applicant's earlier invention and the technology disclosed in Japanese Patent Application Laid-Open No. 1-205028, that is, the cooling conditions of the flange. We will discuss how the passage of time after cooling affects the temperatures of the flange and web, as well as web stress. Figure 4 (a
) shows an example of the cooling curve of air-cooled and water-cooled H-section steel after finish rolling, and Fig. 4(b) shows the change in the thermal stress of the web corresponding to the temperature change in Fig. 4(a). It is. The horizontal axis represents the temperature at the center in the width direction of the web, and the right direction of the horizontal axis indicates a state that changes from high temperature to low temperature over time. Curve 11 is the flange cooling curve in the case of air cooling, and curves 12 to 14 are the flange cooling curves when flange water cooling is started from the time when the web temperature is D.
14 is the cooling of each flange when water cooling is performed for a short time (water cooling ends at temperature E), 14 is water cooling for a long time (water cooling ends at temperature G), and 13 is water cooling between the two (water cooling ends at temperature F). Show a curve. Straight line 15 is the web cooling curve, but since the web is not forcedly cooled, air cooling and
Water cooling is common. Curves 16 to 19 in FIG. Also, curve 20 in the figure. represents the buckling stress of the web, and the higher the temperature, the smaller the value. By the way, as mentioned above, web waves generate compressive internal stress in the web that exceeds the web's buckling limit, so the thermal stress 16 in the case of air cooling in Fig. 4 increases as the temperature decreases, and at point 2 A buckling stress 20 will be reached and web waves will be generated. Curve 17 showing thermal stress of flange water cooling material
What is common in ~19 is that the compressive stress increases as the temperature difference between the flange and the web decreases during water cooling, but
When the water cooling is finished, it changes to the tension side and then changes to the compression side again. This is because the temperature difference between the flange and the web, which was reduced by water cooling, increases and then reduces after water cooling. The compressive stress of the web during water cooling increases as the water cooling time increases, as shown by dots G, H, and H. Conversely, the compressive stress at room temperature decreases as the water cooling time increases, as shown by dots N, S, and C. . Among the short, medium, and long water cooling time conditions mentioned above, the stress during water cooling in stress transition curve 19 with the longest cooling time reaches buckling stress 20 at point Le, and web waves are generated during water cooling. .
また、冷却時間が短い応力曲線１７の場合、水冷中の熱
応力のピーク点ホは座屈応力２０以下であり、水冷中に
ウェブ波が発生することはないが、水冷終了後常温に至
る途中の点ヲで座屈応力２０に達し、ウェブ波が発生す
ることが分かった。即ち、水冷程度が強すざる場合は水
冷中に、また水冷程度が弱すぎる場合には水冷後常温に
至るまでの間にウェブ波が発生している。そして、中間
の水冷時間の場合の熱応力推移１８は水冷中および水冷
後常温に至るまで座屈応力以下であり、この条件のもと
でウェブ波を防止することが可能となる。即ち、薄肉ウ
ェブＨ形鋼の場合は、従来サイズのＨ形鋼における残留
応力軽減法のように、単にフランジとウェブの温度差を
縮小するためのフランジ水冷のみではウェブ波を防止す
ることができない。そこで、本願出願人が先に提案した
特開平１−２０５０２８号において、強制冷却中にウェ
ブ波が発生しない水冷時間の上限もしくは水冷直後のフ
ランジとウェブの温度差の下限と、強制冷却後常温に至
るまでのウェブの熱応力がウェブの座屈応力以下となる
水冷時間の下限もしくは水冷直後のフランジとウェブの
温度差の上限をＨ形鋼のサイズおよび冷却水量密度毎に
予め定めておき、この範囲内で強制冷却する手段を提案
したものである。In addition, in the case of stress curve 17 with a short cooling time, the peak point E of thermal stress during water cooling is less than buckling stress 20, and no web waves are generated during water cooling, but on the way to room temperature after water cooling is completed. It was found that the buckling stress reached 20 at the point , and web waves were generated. That is, if the degree of water cooling is too weak, web waves are generated during water cooling, and if the degree of water cooling is too weak, web waves are generated after water cooling until the temperature reaches room temperature. The thermal stress transition 18 in the case of an intermediate water cooling time is less than the buckling stress during and after water cooling until reaching room temperature, and under this condition it is possible to prevent web waves. In other words, in the case of thin-walled web H-section steel, web waves cannot be prevented by simply water-cooling the flange to reduce the temperature difference between the flange and the web, as in the case of residual stress reduction methods for conventional size H-section steel. . Therefore, in Japanese Patent Application Laid-Open No. 1-205028 previously proposed by the applicant, the upper limit of the water cooling time during which web waves do not occur during forced cooling or the lower limit of the temperature difference between the flange and the web immediately after water cooling, and the lower limit of the temperature difference between the flange and the web immediately after water cooling, and the The lower limit of the water-cooling time during which the thermal stress of the web becomes less than the buckling stress of the web or the upper limit of the temperature difference between the flange and the web immediately after water-cooling is determined in advance for each size of H-beam steel and cooling water flow density. This proposed a means of forced cooling within this range.
薄肉ウェブＨ形鋼の冷却中に発生するウェブ波は、基本
的には上記の冷却手段によって防止可能であるが、水冷
開始時のフランジの温度が高く、水冷時間が長い場合に
はフランジ外側面に焼きが入り、硬度が著しく高くなり
所定の材質を満足することができないことが分かった。Web waves that occur during cooling of thin web H-section steel can basically be prevented by the above-mentioned cooling means, but if the temperature of the flange is high at the start of water cooling and the water cooling time is long, the web waves that occur on the outer surface of the flange It was found that the hardness increased significantly and the specified material quality could not be met.
第１表にその一例を示すが、ウェブ波は防止できてもフ
ランジ表面の硬度が著しく上昇して強度が上昇し、伸び
不足となる場合があることが分かる。即ち、フランジ外
側面の表層部がベーナイト組織となって水冷を行わない
ものに比較して表面硬度（ビッカース硬度）ＩＶ （１
０） ２５０）で９０上昇し、伸びが１４％低下してい
る。An example is shown in Table 1, and it can be seen that even if web waves can be prevented, the hardness of the flange surface increases significantly, the strength increases, and insufficient elongation may occur. In other words, the surface layer of the outer surface of the flange has a bainitic structure, and the surface hardness (Vickers hardness) is lower than that of a bainitic structure without water cooling.
0) 250) has increased by 90, and the growth has decreased by 14%.
そこで本発明者等は、ウェブ波を防止するための前記仕
上げ圧延直後の強度冷却に先立って、フランジ外側面の
表層部組織を微細化しておくことにより、仕上げ圧延後
の冷却によって焼きが入りにくくなることを知見した。Therefore, the inventors of the present invention have refined the surface layer structure of the outer surface of the flange prior to the strength cooling immediately after the finish rolling to prevent web waves, thereby making it difficult for hardening to occur due to the cooling after the finish rolling. I found out that it happens.
具体的な手段としては中間圧延工程でフランジ外側面の
表層部温度を７００℃以下の温度まで強制冷却する工程
と、水冷を停止し再度７００℃を超える温度まで復熱さ
せる復熱工程とを繰り返しながら中間圧延を行い、引続
いて仕上げ圧延および仕上げ圧延直後の冷却を行うもの
である。Specifically, the process involves repeating a process in which the temperature of the surface layer of the outer surface of the flange is forcibly cooled to a temperature of 700°C or less in the intermediate rolling process, and a recuperation process in which water cooling is stopped and the temperature is reheated to a temperature exceeding 700°C. During this process, intermediate rolling is performed, followed by finish rolling and cooling immediately after finish rolling.
第１図は本発明法の中間圧延段階における圧延状況を時
間の経過とＨ形鋼の温度変化との関係で示したものであ
る。第２図はその設備配置例であり、中間圧延機１の前
後面には水冷装置２ａを配置し、次工程の仕上圧延機３
の後面には冷却ウェブ波を防止するための水冷装置２ｂ
を配置している。第１図においてフランジ部の平均温度
は時間の経過と共に漸次低下し°Ｃいくのに対し、フラ
ンジ表層部温度は冷却・復熱を交互に繰り退すため鋸歯
状となっている。このように冷却・復熱を交互に行いつ
つ圧延することによって、フランジ外側面の表層部はフ
ェライトの析出、未変態オーステナイトの微細化の促進
などにより組織を微細化し焼入れ性の低下を達成できる
ものである。なお、本発明において冷却と復熱の境界温
度とした７００℃は、厳密には鋼材成分によって異なる
が、引張強度４０〜５０ ｋｇ／ｍｍ’クラスの一般的
な圧延Ｈ形鋼の成分系では７００℃を実操業の基準値と
して管理すれば本発明の目的は充分に達成されることを
各種試験で確認した結果定めたものである。FIG. 1 shows the rolling conditions in the intermediate rolling stage of the method of the present invention in terms of the relationship between the passage of time and the temperature change of the H-section steel. Fig. 2 shows an example of the equipment arrangement, in which a water cooling device 2a is arranged on the front and rear surfaces of the intermediate rolling mill 1, and a finishing rolling mill 3 for the next process is installed.
There is a water cooling device 2b on the rear surface to prevent cooling web waves.
are placed. In FIG. 1, the average temperature of the flange portion gradually decreases with the passage of time by °C, whereas the temperature of the flange surface layer has a sawtooth shape as cooling and recuperation are alternately repeated. By rolling while performing cooling and reheating alternately in this way, it is possible to refine the structure of the surface layer of the outer surface of the flange by precipitating ferrite and promoting the refinement of untransformed austenite, thereby reducing hardenability. It is. Note that 700°C, which is the boundary temperature between cooling and reheating in the present invention, differs strictly depending on the steel composition, but it is 700°C in the composition system of general rolled H-beam steel with a tensile strength of 40 to 50 kg/mm' class. This was determined after various tests confirmed that the object of the present invention can be fully achieved if the temperature is controlled as a reference value for actual operation.
また、本発明においてフランジ表層部の微細化組織の厚
みは仕上げ圧延後の水冷条件によっても異なるが、フラ
ンジ厚み３０ｍｍ以下のＨ形鋼の場合には５Ｉ１１ｍ以
下で充分である。Further, in the present invention, the thickness of the refined structure in the flange surface layer varies depending on the water cooling conditions after finish rolling, but in the case of an H-beam steel with a flange thickness of 30 mm or less, 5I11 m or less is sufficient.
［実 施 例コ
第３図（ａ）は従来の仕上げ圧延後のフランジ強制冷却
のみの場合のフランジ表層即断面の組織を示し、第３図
（ｂ）は本発明法による中間圧延段階で水冷圧延工程と
復熱工程とを交互に行い且つ、仕上げ圧延後の冷却も行
った場合のフランジ表層部断面組織である。従来法の（
ａ）図では表層部の組織はベーナイトになっているが、
（ｂ）図の組織は微細なフェライト、パーライトとなっ
ていることが分かる。第２表は第２図（ａ） 、 （ｂ
）に対応する仕上げ圧延後の冷却条件および機械的性質
を比較したものである。第２表において従来法の水冷時
間が本発明法よりも長いのは、従来法では中間圧延段階
の冷却工程が無く、冷却ウェブ波防止のために水冷時間
を多くする必要があったためである。[Example Fig. 3(a) shows the structure of the immediate cross-section of the flange surface layer in the case of conventional forced cooling of the flange after finish rolling, and Fig. 3(b) shows the structure of the flange surface layer immediately after water cooling in the intermediate rolling stage according to the method of the present invention. This is a cross-sectional structure of the flange surface layer when the rolling process and the reheating process are performed alternately and cooling is also performed after finish rolling. Conventional method (
a) In the figure, the structure of the surface layer is bainite, but
(b) It can be seen that the structure in the figure consists of fine ferrite and pearlite. Table 2 is shown in Figures 2 (a) and (b).
), the cooling conditions and mechanical properties after finish rolling are compared. The reason why the water cooling time of the conventional method is longer than that of the method of the present invention in Table 2 is because the conventional method did not include a cooling step in the intermediate rolling stage, and it was necessary to increase the water cooling time to prevent cooling web waves.
［発明の効果］
従来の薄肉ウェブＨ形鋼製造法では、仕上げ圧延後の冷
却によってフランジ表面の硬度上昇と材質の劣化が避け
られなかったが、本発明法によればウェブ波発生の防止
は勿論、中間圧延段階の冷却と復熱制御を行うのみでフ
ランジ表面の硬度上昇を抑制でき、特別な合金元素を添
加する必要もないので極めて経済的に薄肉ウェブＨ形鋼
を製造できる。[Effect of the invention] In the conventional thin web H-beam steel manufacturing method, an increase in the hardness of the flange surface and deterioration of the material due to cooling after finish rolling could not be avoided, but according to the method of the present invention, generation of web waves can be prevented. Of course, it is possible to suppress the increase in hardness of the flange surface by simply controlling the cooling and recuperation in the intermediate rolling stage, and there is no need to add any special alloying elements, so the thin-walled web H-section steel can be produced extremely economically.
第１図は本発明法における圧延材の温度推移を示すグラ
フ、第２図は本発明法を実施する装置列例の説明略図、
第３図（ａ） 、 （ｂ）は従来法と本発明法の場合の
フランジ表層即断面の光学顕微鏡組織を示す写真、第４
図（ａ）は冷却条件を変化させた場合のウェブ温度の変
化を示すグラフ、（ｂ）は（ａ）図のウェブ温度に対応
するウェブの応力の変化を説明するグラフである。
１・・・中間圧延機
２ａ・・・中間圧延機前後面Ｃ＊玲装置３・・・仕上圧
延機
２
ｂ・・・仕上圧延機後面の冷却装置
第
図
第
図FIG. 1 is a graph showing the temperature transition of a rolled material in the method of the present invention, FIG. 2 is a schematic illustration of an example of an equipment array for carrying out the method of the present invention,
Figures 3(a) and 3(b) are photographs showing optical microscopic structures of immediate cross-sections of the flange surface layer in the conventional method and the method of the present invention;
Figure (a) is a graph showing changes in web temperature when cooling conditions are changed, and Figure (b) is a graph explaining changes in web stress corresponding to the web temperature in Figure (a). 1... Intermediate rolling mill 2a... Intermediate rolling mill front and rear surfaces C * Rei device 3... Finishing rolling mill 2 b... Cooling device on the rear surface of finishing rolling mill Fig.
Claims (1)
する際に、強制冷却中にウェブ波が発生しない水冷直後
のフランジとウェブの温度差の下限と、強制冷却後常温
に至るまでのウェブの熱応力がウェブの座屈応力以下と
なる水冷直後のフランジとウェブの温度差の上限とをＨ
形鋼のサイズおよび冷却水量密度毎に予め求めておき、
前記温度差の上・下限内でフランジを強制冷却する薄肉
ウェブＨ形鋼の製造方法において、前記仕上げ圧延前の
中間圧延段階でフランジ外側面を強制冷却し、フランジ
外側面の表層部温度を７００℃以下まで水冷する水冷工
程と、水冷を停止しフランジ外側面の表層部温度を７０
０℃超まで復熱させる復熱工程とを繰り返しながら圧延
を行い、所定のフランジ表層部厚さを微細組織とした後
、前記仕上げ圧延および仕上げ圧延直後のフランジ強制
冷却を行うことを特徴とする薄肉ウェブＨ形鋼の製造方
法。1. When forcibly cooling the flange of an H-section steel immediately after hot finish rolling, the lower limit of the temperature difference between the flange and the web immediately after water cooling at which web waves do not occur during forced cooling, and the temperature difference between the web and the web after forced cooling until it reaches room temperature. H is the upper limit of the temperature difference between the flange and the web immediately after water cooling, at which the thermal stress of
Obtain it in advance for each shape steel size and cooling water flow density.
In the method for manufacturing a thin web H-section steel in which the flange is forcibly cooled within the upper and lower limits of the temperature difference, the outer surface of the flange is forcibly cooled in the intermediate rolling stage before the finish rolling, and the temperature of the surface layer of the outer surface of the flange is lowered to 700. A water cooling process in which water cooling is performed to a temperature below
Rolling is performed while repeating a reheating process of reheating to over 0°C to give a predetermined thickness of the flange surface layer a fine structure, and the flange is then subjected to the finish rolling and forced cooling of the flange immediately after the finish rolling. A method for manufacturing thin web H-beam steel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7623690A JPH075962B2 (en) | 1990-03-26 | 1990-03-26 | Method for manufacturing thin web H-section steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7623690A JPH075962B2 (en) | 1990-03-26 | 1990-03-26 | Method for manufacturing thin web H-section steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03274225A true JPH03274225A (en) | 1991-12-05 |
| JPH075962B2 JPH075962B2 (en) | 1995-01-25 |
Family
ID=13599538
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7623690A Expired - Lifetime JPH075962B2 (en) | 1990-03-26 | 1990-03-26 | Method for manufacturing thin web H-section steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH075962B2 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06100924A (en) * | 1992-09-24 | 1994-04-12 | Nippon Steel Corp | Production of shape steel subjected to controlled rolling excellent in fire resistance and toughness |
| US5738739A (en) * | 1993-02-04 | 1998-04-14 | Nippon Steel Corporation | Method for producing low carbon equivalent rolled steel shapes by controlled rolling |
| JP2020157364A (en) * | 2019-03-27 | 2020-10-01 | Ｊｆｅスチール株式会社 | Manufacturing method for h section steel |
| JP2021154365A (en) * | 2020-03-27 | 2021-10-07 | Ｊｆｅスチール株式会社 | Method of manufacturing h-section steel |
| JP2021154366A (en) * | 2020-03-27 | 2021-10-07 | Ｊｆｅスチール株式会社 | Method of manufacturing h-section steel |
-
1990
- 1990-03-26 JP JP7623690A patent/JPH075962B2/en not_active Expired - Lifetime
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06100924A (en) * | 1992-09-24 | 1994-04-12 | Nippon Steel Corp | Production of shape steel subjected to controlled rolling excellent in fire resistance and toughness |
| US5985051A (en) * | 1992-09-24 | 1999-11-16 | Nippon Steel Corporation | Shape steel material having high strength, high toughness and excellent fire resistance and process for producing rolled shape steel of said material |
| US5738739A (en) * | 1993-02-04 | 1998-04-14 | Nippon Steel Corporation | Method for producing low carbon equivalent rolled steel shapes by controlled rolling |
| JP2020157364A (en) * | 2019-03-27 | 2020-10-01 | Ｊｆｅスチール株式会社 | Manufacturing method for h section steel |
| JP2021154365A (en) * | 2020-03-27 | 2021-10-07 | Ｊｆｅスチール株式会社 | Method of manufacturing h-section steel |
| JP2021154366A (en) * | 2020-03-27 | 2021-10-07 | Ｊｆｅスチール株式会社 | Method of manufacturing h-section steel |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH075962B2 (en) | 1995-01-25 |
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