JPS5822522B2 - Manufacturing method for tough, non-tempered high-tensile steel sheets - Google Patents
Manufacturing method for tough, non-tempered high-tensile steel sheetsInfo
- Publication number
- JPS5822522B2 JPS5822522B2 JP9914177A JP9914177A JPS5822522B2 JP S5822522 B2 JPS5822522 B2 JP S5822522B2 JP 9914177 A JP9914177 A JP 9914177A JP 9914177 A JP9914177 A JP 9914177A JP S5822522 B2 JPS5822522 B2 JP S5822522B2
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- Prior art keywords
- temperature
- rolling
- separation
- less
- steel
- Prior art date
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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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
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- 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 Steel (AREA)
Description
【発明の詳細な説明】
この発明は、低温靭性に優れ、かつ低温靭性試験におけ
る試験破面にセパレーションを呈さない強靭非調質高張
力鋼板の製造法に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a tough, non-heat-treated high-strength steel sheet that has excellent low-temperature toughness and does not exhibit separation on the test fracture surface in a low-temperature toughness test.
コントロールトローリング法による非調質高張力鋼板の
製造において、この方法の特色である圧延時に低温度域
（約９００°Ｃ以下）で強圧下を行なった鋼板は、シャ
ルピー試、験やＢ−ＤＷＴＴ試験（バラチル式落重試験
）などの試験結果では、破断面にセパレーションと称す
る縦割れが生ずることがある。In the production of non-temperature high-strength steel sheets using the controlled trawling method, the steel sheets that are subjected to strong reduction at a low temperature range (approximately 900°C or less) during rolling, which is a feature of this method, are tested by the Charpy test, the B-DWTT test, and the B-DWTT test. According to test results such as (Baracil drop weight test), vertical cracks called separations may occur on the fracture surface.
このセパレーションは、鋼の脆性破壊に対する抵抗を強
める作用がある反面、ガス輸送用パイプラインなど最近
問題になっている不安定延性破壊に対する影響が未だ十
分に解明されていないため、セパレーションを好まない
傾向も一部には見受けられる。Although this separation has the effect of increasing the resistance of steel to brittle fracture, there is a tendency to dislike separation because its effect on unstable ductile fracture, which has recently become a problem in gas transportation pipelines, is not yet fully understood. can also be seen in some cases.
そのために、セパレーションがなく、しかも良好な低温
靭性を有する鋼の製造法の確立がかかる要求に対しては
望まれていた。Therefore, it has been desired to meet these demands by establishing a method for manufacturing steel that is free from separation and has good low-temperature toughness.
セパレーションを防止するのは圧延最終温度が鋼のＡｒ
３変態点以上（約７５０°Ｃ以上）になるように圧延を
終了するのが従来技術であった。The final rolling temperature is the Ar of steel that prevents separation.
The conventional technique was to finish rolling so that the temperature reaches 3 transformation points or higher (approximately 750° C. or higher).
しかし、この温度以上では、コントロールトローリング
法の特色である最終圧延温度を低くして、成品のミクロ
組織を微細化し、強度及び靭性を改善するということが
十分活かされなかった。However, above this temperature, the characteristic of the controlled trawling method, which is to lower the final rolling temperature to refine the microstructure of the finished product and improve its strength and toughness, was not fully utilized.
そのために、従来公知技術では成分元素を増加させて補
なわなければならず、これに伴うコスト高や溶接性の低
下及び低温靭性の劣化を伴なっていた。For this reason, in the conventionally known technology, it was necessary to compensate by increasing the number of component elements, which was accompanied by an increase in cost, a decrease in weldability, and a deterioration in low-temperature toughness.
発明者は、従来技術だけでは低温靭性の優れた鋼の製造
においてセパレーションは完全に消滅せず種々検討の結
果最適な圧下率と限定温度の関係からセパレーションを
生成しない強靭非調質高張力鋼板の製造法を見い出した
。The inventor found that conventional techniques alone do not completely eliminate separation in the production of steel with excellent low-temperature toughness, and as a result of various studies, the inventor has developed a strong, non-tempered, high-strength steel plate that does not produce separation, based on the relationship between the optimal rolling reduction rate and limiting temperature. Found a manufacturing method.
つまり、この発明は鋼を１０５０〜１２００’Ｃに加熱
した後、９００℃以下で仕上板厚に対し圧下率６０〜８
０係で圧延を行ない、この際上記圧下率のうち５０〜６
０％の圧延を９００〜８００℃の温度範囲で行ない、残
りの圧下率１０〜２０％の圧延を８００°Ｃ以下の温度
で、最終パス温度が６９０〜７５０°Ｃの温度範囲にあ
り、かつ１パスの川下率が５〜ｌＯ％の範囲となるパス
回数で圧延することを特徴とするものである。In other words, in this invention, after heating steel to 1050-1200'C, the reduction rate is 60-88% with respect to the finished plate thickness at 900°C or less.
Rolling is carried out at a rolling ratio of 0, and at this time, the rolling reduction rate is 50 to 6.
0% rolling is carried out in a temperature range of 900 to 800 °C, the remaining rolling reduction of 10 to 20% is carried out at a temperature of 800 °C or less, and the final pass temperature is in a temperature range of 690 to 750 °C, and It is characterized by rolling with a number of passes such that the downstream rate per pass is in the range of 5 to 10%.
次に、上記加工条件の限定理由を説明する。Next, the reason for limiting the above processing conditions will be explained.
鋼の加熱温度を１０５０〜１２００°Ｃとしたのは、１
０５０℃以下だとバナジウム、ニオブ等の添加元素が鋼
中に十分固溶せず、この元素の析出硬化による強度の確
保が不十分となるため、および加熱温度が低くなると圧
延中にフェライト変態を生じやすくなり、これがセパレ
ーションを誘発するからであり、１２００°Ｃ以上では
オーステナイト粒が粗大化し、最終成品にて所定の細粒
鋼が得られなく、良好な低温靭性の確保が困難となるた
めである。The reason why the heating temperature of steel was set to 1050 to 1200°C was 1.
If the heating temperature is lower than 050°C, additional elements such as vanadium and niobium will not form a solid solution in the steel, making it insufficient to secure strength through precipitation hardening of these elements, and if the heating temperature is low, ferrite transformation may occur during rolling. This is because the austenite grains become coarser at temperatures above 1200°C, making it impossible to obtain the desired fine-grained steel in the final product and making it difficult to ensure good low-temperature toughness. be.
また、９００℃以下で仕上板厚に対し、圧下率を６０〜
８０％としたのは、６０％以下だと結晶粒の細粒化効果
が小さく良好な低温靭性が得られないことがら圧下率６
０係以上に限定した。In addition, at 900℃ or less, the rolling reduction rate is 60 to 60% relative to the finished plate thickness.
The reason for setting the reduction rate to 80% is that if it is less than 60%, the grain refining effect is small and good low-temperature toughness cannot be obtained.
Limited to those in charge 0 or above.
又、８０％以上では加工によるフェライト変態の促進作
用により低温圧延によりセパレーションが生成しやすく
なるために８０％以下でなければならなし）。In addition, if it is 80% or more, separations are likely to be generated by low-temperature rolling due to the promotion of ferrite transformation during processing, so it must be 80% or less).
これらの川下温度が９００°Ｃ以上の温度になると良好
な低温靭性は得られない。If these downstream temperatures reach 900°C or higher, good low-temperature toughness cannot be obtained.
上記６０〜８０係の圧下率のうち先ず仕上圧延温度が８
００〜９００°Ｃの温度範囲で５０〜６０係の圧延を行
うのはシャルピー試１験やＢ−ＤＷＴＴ試験などの靭性
の試験で、破断面にセパレーションを出さない限界まで
８００℃以上の温度域にてほとんどの圧下を終了させて
おくためである。Among the above rolling reduction ratios of 60 to 80, the finish rolling temperature is 8
In toughness tests such as the Charpy test and the B-DWTT test, rolling at 50 to 60 in a temperature range of 00 to 900°C is carried out in a temperature range of 800°C or higher to the limit of not producing separation on the fracture surface. This is to complete most of the reduction at .
５０〜６０％の圧下が８００℃以下になるとセパレーシ
ョンが生成しやすくなる。When the 50 to 60% reduction is 800°C or less, separation tends to occur.
この発明の目的とする低温靭性の優れた鋼を得るために
は８００〜９００°Ｃで強圧下を行う必要があり、従来
開示されている７５０℃以上で圧延を終了する限定条件
のみでは良好な低温靭性、セパレーション抑制の２点を
満足しない。In order to obtain steel with excellent low-temperature toughness, which is the object of this invention, it is necessary to carry out strong reduction at 800 to 900°C, and the conventionally disclosed limited condition of finishing rolling at 750°C or higher is insufficient. The two points of low temperature toughness and separation suppression are not satisfied.
そして残存圧下率１０〜２０％の圧下を８００℃以下の
温度で最終パス温度が６９０〜７５０°Ｃの温度範囲に
あり、かつ１パスの圧下率を５〜ＩＯ％の範囲と限定し
たのは次の理由による。And the final pass temperature is in the temperature range of 690 to 750 °C with a residual reduction of 10 to 20% at a temperature of 800 °C or less, and the reduction in one pass is limited to a range of 5 to IO%. Due to the following reasons.
この発明の目的の１つである高強度鋼を得るためには８
００℃以下での圧延により転位密度の高い鋼を作る必要
がある。In order to obtain high-strength steel, which is one of the purposes of this invention, 8
It is necessary to produce steel with a high dislocation density by rolling at temperatures below 00°C.
そのために最小限１０％以上の圧下を８００°Ｃ以下で
実施し、かつ最終パス温度は転位密度を高めるのに最も
有効な温度である７５０℃以下６９０°Ｃ以上とした。For this purpose, a minimum reduction of 10% or more was carried out at 800°C or lower, and the final pass temperature was set to 750°C or lower and 690°C or higher, which is the most effective temperature for increasing the dislocation density.
しかしながら一方で８００°Ｃ以下の圧下は鋼のセパレ
ーション生成作用を促進するものであり、これは鋼の高
強度化と矛盾するものである。However, on the other hand, a reduction of 800°C or less promotes separation formation in the steel, which is inconsistent with increasing the strength of the steel.
この発明の特色はこの矛盾する条件の中から最適な組み
合わせを発明したものであり、セパレーション抑制のた
めには８００°Ｃ以下の圧下を２０％以下に抑えねばな
らない。The feature of this invention is that the optimum combination has been invented among these contradictory conditions, and in order to suppress separation, the rolling reduction at 800° C. or less must be suppressed to 20% or less.
かつ、１パス５％〜１０％の圧下制限は圧延強化のため
に必要な１パス最小圧下率５％以上と、セパレーション
Ｆ’＄１Ｊに必要な１パス最大圧下率１０％以Ｆにより
制限されるものである。In addition, the 1-pass rolling reduction of 5% to 10% is limited by the minimum 1-pass rolling reduction of 5% or more necessary for rolling reinforcement and the maximum 1-pass rolling reduction of 10% or less F required for separation F'$1J. It is something that
最終パス温度を６９０°Ｃ以上に限定したのは、・これ
以下の温度になると良好な低温靭性の維持が困難となる
からである。The reason why the final pass temperature was limited to 690°C or higher is because: If the temperature is lower than this, it becomes difficult to maintain good low-temperature toughness.
この発明の実施にあたっては特に成分元素を特定化する
必要はないが、実用的な見地からは、次の化学組成の鋼
への適用が望ましい。In carrying out this invention, it is not necessary to specify the constituent elements in particular, but from a practical standpoint, it is desirable to apply the invention to steel having the following chemical composition.
炭素０．２０％以下、けい素０．６０％以下、マンガン
０．８〜１．８係、酸可溶アルミニウム０．０１〜０．
０６％、ニオブ０．０８％以下、に０，２０％以下のバ
ナジウムおよびチタン、ジルコニウム、１％以下の銅、
ニッケル、クロム、モリブデンの１種又は２種以上を含
み、残部鉄又は不可避的不純物からなる鋼、又は炭素０
．２０％以下、けい素ｏ、６ｏ％以下、７７ｆｊ”１０
．８〜１．８％、酸可溶アルミニウム０．０１〜０．０
６％、残部鉄又は不可避的不純物からなる鋼である。Carbon 0.20% or less, silicon 0.60% or less, manganese 0.8-1.8%, acid-soluble aluminum 0.01-0.
0.06%, 0.08% or less niobium, 0.20% or less vanadium and titanium, zirconium, 1% or less copper,
Steel containing one or more of nickel, chromium, and molybdenum, with the balance consisting of iron or unavoidable impurities, or carbon-free
．． 20% or less, silicon o, 6o% or less, 77fj”10
．． 8-1.8%, acid-soluble aluminum 0.01-0.0
6%, balance iron or unavoidable impurities.
以下において実施例にて本発明の効果を示す。The effects of the present invention will be shown in Examples below.
実施例 １
化学組成炭素０，１０％、けい素ｏ、３ｓ％、マンガン
１．４係、酸可溶アルミニウム０．０３％、ニオブ０．
０３％、バナジウム０．０７％、銅０．１５％、クロム
ｏ、ｉ５％、残部鉄および不可避的不純物よりなる鋼を
用いて板厚１６．５０Ｍの鋼を種々の加熱・圧延条件に
て製造し、シャルピーおよびＢ−ＤＷＴＴ試、験破面の
セパレーション発生状況と機械的性質の関係を調べた。Example 1 Chemical composition Carbon: 0.10%, silicon: O: 3s%, manganese: 1.4%, acid-soluble aluminum: 0.03%, niobium: 0.0%.
03% vanadium, 0.07% vanadium, 0.15% copper, 5% chromium O, i5%, the balance iron and unavoidable impurities to produce steel with a thickness of 16.50M under various heating and rolling conditions. Then, the Charpy and B-DWTT tests were conducted, and the relationship between the occurrence of separation on the test fracture surface and mechanical properties was investigated.
結果の要約が第１図であり、圧延温度と川下率の関係で
示す第１図にて領域ｌはセパレーションは発生しないが
、低温靭性・強度が所要の性能を満たさない領域、領域
■は低温靭性、強度とも良好であるが、セパレーション
を生成する領域である。A summary of the results is shown in Figure 1. In Figure 1, which shows the relationship between rolling temperature and downstream rate, area l is an area where separation does not occur, but low temperature toughness and strength do not meet the required performance, and area ■ is a low temperature area. Although both toughness and strength are good, this is a region where separation occurs.
結局、斜線部で示した領域を満たす圧延温度−圧下率に
沿って製造された鋼のみが、低温靭性、強度が良好で、
セパレーションを生成しない唯一の組み合わせであるこ
とが判った。In the end, only steel manufactured according to the rolling temperature and reduction ratio that satisfies the shaded area has good low-temperature toughness and strength.
This was found to be the only combination that did not produce separation.
第１表には具体的に代表例について試験結果を示す。Table 1 specifically shows test results for representative examples.
降伏点５０．ＯＫｐ／−以上、引張強さ６０．ＯＫｙ／
−以上、−３０°ＣでのＢ−ＤＷｒＴの延性破面率１０
０％、シャルピー、Ｂ−ＤＷＴＴのセパレーション無し
と云う目標性能に対して第１図領域Ｉに属す比較例１は
セパレーションは示さないが、強度、靭性が不足し、領
域■に属す比較例２，３゜４は強度、靭性は満足するが
、いずれもセパレーションを生成している。Yield point 50. OKp/- or more, tensile strength 60. OKy/
- Above, ductile fracture ratio of B-DWrT at -30°C 10
0%, Charpy, and B-DWTT with no separation, Comparative Example 1, which belongs to Area I in Figure 1, does not show separation, but lacks strength and toughness, and Comparative Example 2, which belongs to Area ■, shows no separation. 3°4 satisfies the strength and toughness, but both produce separation.
両性能を満たすのは、この発明に基づ〈実施例１，２の
みである。Only Examples 1 and 2 based on the present invention satisfy both performances.
実施例 ２ 次にこの発明による量産ベースでの実施例を示す。Example 2 Next, an embodiment of the present invention on a mass production basis will be shown.
化学組成炭素０．１２％、けい素０．３０％、マンガン
１．３５％、ニオブ０．３０％、バナジウム０．０６％
、酸可溶アルミニウム０．０３％、残部鉄および不可避
的不純物よりなる厚み２３０Ｍのスラブを１１００〜１
１７０℃に加熱後、９００°Ｃ以下の圧下率が仕上板厚
に対し７５％になるごとくかつ８００℃以下１５％の圧
下を３バスにて最終仕上圧延温度が７２０℃±１０°Ｃ
の範囲で各パスの圧下率をそれぞれ５係で板厚１６．５
（ｌｌ’２、幅４５ＱＱ７１ｍ、長さ２５ｍの鋼板の圧
延を行った。Chemical composition Carbon 0.12%, Silicon 0.30%, Manganese 1.35%, Niobium 0.30%, Vanadium 0.06%
, 230M thick slab consisting of 0.03% acid-soluble aluminum, balance iron and unavoidable impurities.
After heating to 170°C, final rolling temperature is 720°C ± 10°C with 3 baths such that the rolling reduction ratio of 900°C or less is 75% of the finished plate thickness and 15% reduction of 800°C or less.
The plate thickness is 16.5 with the rolling reduction rate of each pass being 5 in the range of
(A steel plate with a width of 45QQ71m and a length of 25m was rolled.
この鋼板について機械的諸性質の試験を行った結果セパ
レーション発生は認められず、強度、靭性の優れた、か
つ炭素当量の低い溶接性の優れた鋼板の製造結果が得ら
れた。As a result of testing various mechanical properties of this steel plate, no separation was observed, and a steel plate with excellent strength and toughness, low carbon equivalent, and excellent weldability was obtained.
第２表に機械試験結果を示す。Table 2 shows the mechanical test results.
この発明は上述のごとく、シャルピーあるいはＢ−ＤＷ
ＴＴ試験片の破断面にセパレーションを生成せず、強度
、低温靭性ともに優れた強靭非調質の高張力鋼板が得ら
れる。As mentioned above, this invention is based on Charpy or B-DW.
A tough, untempered high-strength steel plate with excellent strength and low-temperature toughness can be obtained without forming separation on the fracture surface of the TT test piece.
第１図はこの発明の圧延温度と成品厚さに対する残存川
下率との関係において、セパレーション出現の有無を示
した図表である。
図中Ｉの領域はセパレーションは生成しないが低温靭性
は不足である。
■の領域はこの発明の領域でセパレーションは生成せず
低温靭性良好な範囲を示す。
■の領域は低温靭性は良好であるがセパレーションの生
成する範囲である。FIG. 1 is a chart showing the presence or absence of separation in the relationship between the rolling temperature and the residual downstream ratio with respect to the thickness of the product according to the present invention. In the region I in the figure, separation does not occur, but low-temperature toughness is insufficient. The region (2) is the region of the present invention, where no separation occurs and the low-temperature toughness is good. In the region (2), low temperature toughness is good, but separation occurs.
Claims (1)
１２００℃に加熱した後、９００℃以下で仕上板厚に対
し圧下率６０〜８０％で圧延を行ない、この際上記圧下
率のうち５０〜６０係の圧延を９００〜８００°Ｃの温
度範囲で行ない、残りの圧下率１０〜２０％の圧延を８
００°Ｃ以下の温度で、かつ最終パス温度が６９０〜７
５０°Ｃの温度範囲にあり、それぞれの１パスの圧下率
が５〜ｌｏ％の範囲となるごときパス回数で圧延し、低
温靭性試１験においてセパレーションを呈さないことを
特徴とする強靭非調質高張力鋼板の製造法。1 In the production of non-tempered high tensile strength steel sheets, steel is heated to 1050~
After heating to 1200°C, rolling is performed at a reduction rate of 60 to 80% of the finished plate thickness at 900°C or less, and at this time, rolling at a reduction rate of 50 to 60 of the above reduction rate is performed at a temperature range of 900 to 800°C. Then, roll the remaining rolling at a reduction rate of 10 to 20% for 8
00°C or less, and the final pass temperature is 690~7
A tough and non-tough material that is rolled in a temperature range of 50°C and with a number of passes such that the rolling reduction of each pass is in the range of 5 to 10%, and does not exhibit separation in one low-temperature toughness test. Manufacturing method for high-quality high-tensile steel sheets.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9914177A JPS5822522B2 (en) | 1977-08-18 | 1977-08-18 | Manufacturing method for tough, non-tempered high-tensile steel sheets |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9914177A JPS5822522B2 (en) | 1977-08-18 | 1977-08-18 | Manufacturing method for tough, non-tempered high-tensile steel sheets |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5433219A JPS5433219A (en) | 1979-03-10 |
| JPS5822522B2 true JPS5822522B2 (en) | 1983-05-10 |
Family
ID=14239417
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9914177A Expired JPS5822522B2 (en) | 1977-08-18 | 1977-08-18 | Manufacturing method for tough, non-tempered high-tensile steel sheets |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5822522B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3070180D1 (en) * | 1979-12-06 | 1985-03-28 | Salzgitter Peine Stahlwerke | Hot rolled strip or plate of denitrided steel and process for its production |
-
1977
- 1977-08-18 JP JP9914177A patent/JPS5822522B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5433219A (en) | 1979-03-10 |
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