JPH0387333A - High strength-low alloy-heat resistant steel - Google Patents
High strength-low alloy-heat resistant steelInfo
- Publication number
- JPH0387333A JPH0387333A JP22169989A JP22169989A JPH0387333A JP H0387333 A JPH0387333 A JP H0387333A JP 22169989 A JP22169989 A JP 22169989A JP 22169989 A JP22169989 A JP 22169989A JP H0387333 A JPH0387333 A JP H0387333A
- Authority
- JP
- Japan
- Prior art keywords
- steel
- low alloy
- temperature
- strength
- temp
- 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
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 73
- 239000010959 steel Substances 0.000 title claims abstract description 73
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 9
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 8
- 239000000956 alloy Substances 0.000 claims abstract description 8
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 8
- 238000001816 cooling Methods 0.000 claims abstract description 7
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 6
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 5
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 5
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 4
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 4
- 229910052759 nickel Inorganic materials 0.000 claims abstract 2
- 239000012535 impurity Substances 0.000 claims description 3
- 229910000859 α-Fe Inorganic materials 0.000 abstract description 11
- 239000000203 mixture Substances 0.000 abstract description 5
- 229910052721 tungsten Inorganic materials 0.000 abstract description 4
- 238000005242 forging Methods 0.000 abstract description 3
- 229910052748 manganese Inorganic materials 0.000 abstract description 3
- 238000005096 rolling process Methods 0.000 abstract description 3
- 229910000851 Alloy steel Inorganic materials 0.000 abstract description 2
- 229910001563 bainite Inorganic materials 0.000 abstract description 2
- 238000010438 heat treatment Methods 0.000 abstract description 2
- 229910001562 pearlite Inorganic materials 0.000 abstract description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract 1
- 229910000922 High-strength low-alloy steel Inorganic materials 0.000 abstract 1
- JMANVNJQNLATNU-UHFFFAOYSA-N oxalonitrile Chemical compound N#CC#N JMANVNJQNLATNU-UHFFFAOYSA-N 0.000 abstract 1
- 230000000694 effects Effects 0.000 description 17
- 239000000463 material Substances 0.000 description 12
- 230000007423 decrease Effects 0.000 description 8
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 5
- 230000003647 oxidation Effects 0.000 description 5
- 238000007254 oxidation reaction Methods 0.000 description 5
- 239000002244 precipitate Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 239000003795 chemical substances by application Substances 0.000 description 4
- 238000005336 cracking Methods 0.000 description 4
- 230000007704 transition Effects 0.000 description 4
- 150000001247 metal acetylides Chemical class 0.000 description 3
- 238000005728 strengthening Methods 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 239000002436 steel type Substances 0.000 description 2
- 230000035882 stress Effects 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 238000000137 annealing Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000009863 impact test Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
- 238000011282 treatment 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〕
本発明は高強度低合金耐熱鋼に関し、例えば発電用ボイ
ラや化学プラントの熱交換器、配管等の鋼管材、高温耐
圧バルブなどの鋼鍛鋼品、高温で使用される吊金具、支
持材などの丸鋼、形鋼、鋼板などに適用される高強度低
合金耐熱鋼に関する。[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to high-strength, low-alloy heat-resistant steel, such as forged steel for power generation boilers, heat exchangers for chemical plants, steel pipe materials for piping, high-temperature pressure-resistant valves, etc. This product relates to high-strength, low-alloy heat-resistant steel that is applied to round steel, shaped steel, steel plates, etc., such as products, hanging fittings used at high temperatures, and supporting materials.
従来、耐熱鋼としてはオーステナイト系ステンレス鋼、
ＱＣｒ鋼、１２Ｃｒ鋼、１〜２′／ＡＣｒ鋼及び１．０
％未満のＣｒを含有する低合金鋼などがある。Traditionally, heat-resistant steels include austenitic stainless steel,
QCr steel, 12Cr steel, 1~2'/ACr steel and 1.0
There are low alloy steels containing less than % Cr.
上記の従来の耐熱鋼の場合、約６００℃までの高温で使
用することを条件とすると、次のような問題点がある。In the case of the above-mentioned conventional heat-resistant steel, when used at high temperatures up to about 600° C., there are the following problems.
■ オーステナイト系ステンレス鋼：高温強度、靭性、
加工性は良好であるが、使用環境によっては応力腐食割
れ、粒界腐食が生じる欠点があり、また材料価格が高い
。■ Austenitic stainless steel: high temperature strength, toughness,
Although it has good workability, it has the disadvantage that stress corrosion cracking and intergranular corrosion may occur depending on the usage environment, and the material cost is high.
■ ９Ｃｒ鋼及び１２Ｃｒ鋼二種々の鋼種があるが、５
ＴＢＡ２６ （９Ｃｒ−ＩＭｏ鋼）やＤＩＮ規格Ｘ２０
ＣｒＭｏＶ１２１ （１２Ｃｒ−ＩＭｏ−Ｖ鋼〉はＣ量
が約０．１３〜０．２５ｗｔ％と高いために、溶接割れ
が発生しやすく、また加工性が劣る。■ There are two types of steel, 9Cr steel and 12Cr steel, but 5
TBA26 (9Cr-IMo steel) or DIN standard X20
Since CrMoV121 (12Cr-IMo-V steel) has a high C content of approximately 0.13 to 0.25 wt%, weld cracking is likely to occur and workability is poor.
最近開発された低Ｃ系でＶ及びＮｂを添加した９Ｃｒ鋼
及び１２Ｃｒ鋼は上記の高Ｃ系の鋼種に比べ、溶接性及
び高温強度とも改善されているが、２ｙ４Ｃｒ−ＩＭｏ
鋼などの低合金鋼に比べ、熱伝導率が低く全般に溶接作
業性が劣る。The recently developed 9Cr steel and 12Cr steel with added V and Nb have improved weldability and high-temperature strength compared to the above-mentioned high C steel types, but 2y4Cr-IMo
Compared to low alloy steels such as steel, it has lower thermal conductivity and is generally inferior in welding workability.
■ １〜２％Ｃｒ鋼：この鋼は約６００℃まで使用でき
る耐酸化性があり、５ＴＢＡ２６を含めた低合金鋼の中
でも最も高温強度が優れ、溶接性及び加工性が良好であ
る。しかし、最近開発された高強度の９Ｃｒ鋼及び１２
Ｃｒ鋼やオーステナイト系ステンレス鋼に比べ、高温強
度が劣るため、木調を使用する場合、６００℃付近の設
計温度では極厚となり、配管などの大径管では大きな熱
応力が発生することになる。(1-2% Cr steel): This steel has oxidation resistance that can be used up to about 600°C, has the best high-temperature strength among low alloy steels including 5TBA26, and has good weldability and workability. However, recently developed high-strength 9Cr steel and 12Cr steel
Compared to Cr steel and austenitic stainless steel, it has inferior high-temperature strength, so if wood-like material is used, it will be extremely thick at a design temperature of around 600°C, and large diameter pipes such as piping will experience large thermal stress. .
■ １．０％未満のＣｒを含有する低合金鋼：１〜２％
Ｃｒ鋼に比べて高温強度が低く、耐酸化性が劣るため、
使用限界温度が低い欠点がある。■ Low alloy steel containing less than 1.0% Cr: 1-2%
Compared to Cr steel, it has lower high temperature strength and poor oxidation resistance,
It has the disadvantage of a low operating temperature limit.
また、ＶやＮｂを微量添加し、高温強度の向上を図った
鋼では溶接熱などにより再結晶し、微細化した部分は原
質部に比べて硬さが低下し、引張あるいはクリープ破断
試験片の形状によっては、この部分で破断し、原質部よ
りも低い強度を示すことがある。In addition, in steels with trace amounts of V or Nb added to improve high-temperature strength, they recrystallize due to welding heat, etc., and the hardness of the refined parts is lower than that of the original parts, resulting in a tensile or creep rupture test specimen. Depending on the shape of the material, it may break at this part and exhibit lower strength than the original part.
また、低Ｃ−１〜２ｙ４Ｃｒ鋼系で、Ｍｏ、 Ｗ。Also, low C-1~2y4Cr steel system, Mo, W.
Ｖ、Ｎｂを添加した鋼はフェライト相が多く靭性が低い
欠点がある。Steels to which V and Nb are added have a disadvantage of having a large amount of ferrite phase and low toughness.
本発明は上記技術水準に鑑み、上記のような従来鋼種の
欠点をなくして溶接熱影響部の軟化の程度を軽減し、さ
らに母地のシャルピー衝撃値を改善した上で、約６００
℃までオーステナイト系ステンレス鋼及び高強度９ Ｃ
ｒｗＪや１２Ｃｒ鋼に代えて使用できる鋼を提供しよう
とするものである。In view of the above-mentioned state of the art, the present invention eliminates the drawbacks of conventional steel types as described above, reduces the degree of softening of the weld heat-affected zone, and further improves the Charpy impact value of the base material.
Austenitic stainless steel and high strength up to 9C
The purpose is to provide a steel that can be used in place of rwJ and 12Cr steel.
本発明は、重量％で、Ｃ：ｏ、ｏ ３〜０．１２、Ｓｉ
≦１％、Ｍｎ：０．２〜１％、Ｐ≦０６０３％、Ｓ≦０
．０３％、Ｎ！≦０．８％、Ｃｒ：０．７〜３％、ＭＯ
二〇、３〜１．５％、Ｖ：０．０５〜０．３５％、Ｎｈ
：０．０１〜０．１２％、Ｎ：０．０１〜０．０５％を
含み、あるいは更にＷ ： ０．５〜２．４％、Ｂ：０
、０００５〜０．０１５％、ＡＩ≦０．０５％、Ｔｉ：
０．０５〜０．２％の１種以上を含む残部Ｐｅ及び不可
避の不純物からなる鋼を、オーステナイト化温度以上に
加熱したのち圧延または鍛造し、それを冷却途中あるい
は一旦Ａｃ、温度以下に冷却したのち、再度オーステナ
イト化温度以上に加熱して冷却途中のＡｒ３よりも高い
温度からＡｒ。In the present invention, C: o, o 3 to 0.12, Si
≦1%, Mn: 0.2-1%, P≦0603%, S≦0
．． 03%, N! ≦0.8%, Cr: 0.7-3%, MO
20, 3-1.5%, V: 0.05-0.35%, Nh
: 0.01 to 0.12%, N: 0.01 to 0.05%, or further W: 0.5 to 2.4%, B: 0
, 0005-0.015%, AI≦0.05%, Ti:
Steel consisting of the balance Pe and unavoidable impurities containing 0.05 to 0.2% of one or more types is heated to above the austenitizing temperature, then rolled or forged, and then cooled during cooling or once cooled to below Ac temperature. After that, it is heated again to the austenitizing temperature or higher, and Ar is applied from a temperature higher than Ar3 during cooling.
直上の温度域で連続して圧延または鍛造してなることを
特徴とする高強度低合金耐熱鋼である。This is a high-strength, low-alloy, heat-resistant steel that is continuously rolled or forged in a temperature range immediately above that of the steel.
本発明鋼の金属組織はフェライト＋ベーナイトあるいは
フェライト＋パーライトであり、通常の１〜２％Ｃｒ鋼
に比ベフエライトの量が多い。The metal structure of the steel of the present invention is ferrite + bainite or ferrite + pearlite, and the amount of beferrite is larger than that of ordinary 1-2% Cr steel.
このフェライト相内には微細なＶＮ析出物が生成すると
ともに圧延、鍛造処理によって結晶粒が著しく細粒化す
る。Fine VN precipitates are generated within this ferrite phase, and the crystal grains are significantly refined by rolling and forging treatments.
以下、本発明鋼における成分範囲の限定理由を説明する
。説明中％はｗｔ％を示す。The reasons for limiting the range of components in the steel of the present invention will be explained below. In the explanation, % indicates wt%.
■Ｃ：ＣはＣｒ、 Ｍｏ、 Ｗ、 Ｖ、 Ｎｂととも
に炭化物を形成し、クリープ強度を上昇させる。しかし
、０．１２％を越えると溶接割れが生じやすく、またか
えってクリープ強度を低下させることになる。一方、ク
リープ強度上昇のためには０．０３％以上が必要であり
、これを下田るとクリープ強度が低下する。従って０．
０３〜０．１２％とした。好ましくは０．０５〜０．０
９％である。■C: C forms carbides with Cr, Mo, W, V, and Nb, and increases creep strength. However, if it exceeds 0.12%, weld cracking is likely to occur and creep strength will be reduced. On the other hand, in order to increase the creep strength, 0.03% or more is required, and if this content is lowered, the creep strength decreases. Therefore 0.
03 to 0.12%. Preferably 0.05-0.0
It is 9%.
■Ｓｉ ： Ｓｉは脱酸剤として用いられ、強度上昇、
耐酸化性向上に寄与するが１％を越えて添加すると靭性
が低下し、クリープ延性を低下させるので１％以下とし
た。好ましくは０．２％以下である。■Si: Si is used as a deoxidizing agent, increasing strength,
Although it contributes to improving oxidation resistance, adding more than 1% lowers toughness and lowers creep ductility, so the content was set at 1% or less. Preferably it is 0.2% or less.
■Ｍｎ：ＭｎはＳｉと同様に脱酸剤としての効果を有し
、焼入れ性を向上させるが、０．２％未満では、その効
果が少なく、また１％を越えて添加すると脆化しやすい
ので０．２〜１％とした。■Mn: Like Si, Mn has an effect as a deoxidizing agent and improves hardenability, but if it is less than 0.2%, the effect is small, and if it is added in excess of 1%, it tends to become brittle. The content was set at 0.2 to 1%.
好ましくは０．４〜０．６％である。Preferably it is 0.4 to 0.6%.
■Ｐ及びＳ：これらＰ及びＳは不純物元素として靭性を
低下させ機械的性を劣化させるので、ともに０．０３％
以下とした。好ましくはＰは０．０１％以下、Ｓは０．
００５％以下である。■P and S: These P and S reduce toughness and mechanical properties as impurity elements, so both are 0.03%.
The following was made. Preferably P is 0.01% or less and S is 0.01% or less.
0.005% or less.
■Ｎｉ ： Ｎｉは焼入れ性を向上させ、靭性を改善す
る元素であるが、０．８％を越えて添加すると硬化性が
大きくなり、溶接性が低下すると同時にクリープ破断強
度を低下させるので、０．８％以下とした。好ましくは
０．４％以下である。■Ni: Ni is an element that improves hardenability and toughness, but if added in excess of 0.8%, hardenability increases, weldability decreases, and at the same time creep rupture strength decreases. .8% or less. Preferably it is 0.4% or less.
■Ｃｒ ： Ｃｒは耐酸化性を高め、適性な量であれば
炭化物形成元素としてクリープ破断強度を高めるが、添
加量が多くなると熱伝導率が小さくなるとともに、かえ
ってクリープ破断強度を低下させる。また、０．７％を
下調る量では耐酸化性の面から約６００℃まで使用する
ことは困難になり、クリープ破断強度も低下する。そこ
で下限を０．７％、上限を３％とした。■Cr: Cr increases oxidation resistance and increases creep rupture strength as a carbide-forming element if added in an appropriate amount, but when added in a large amount, thermal conductivity decreases and the creep rupture strength is reduced. Further, if the amount is less than 0.7%, it becomes difficult to use up to about 600°C from the viewpoint of oxidation resistance, and the creep rupture strength also decreases. Therefore, the lower limit was set to 0.7% and the upper limit was set to 3%.
好ましくは０．９〜２．４％である。Preferably it is 0.9 to 2.4%.
■Ｍｏ ： Ｍｏは母地に固溶するとともに炭化物など
の析出物を形成してクリープ破断強度を高めるが、０．
３％未満では不十分であり、１．５％を越えて添加して
も、その効果は飽和し、靭性が低下してくる。また、Ｍ
ｏの多量の添加は熱間加工性を阻害するのでＭｏの添加
量は０．３〜１．５％とした。好ましくは０．７〜１．
３％である。■Mo: Mo dissolves in the matrix and forms precipitates such as carbides to increase creep rupture strength, but 0.
If it is less than 3%, it is insufficient, and if it is added in excess of 1.5%, the effect will be saturated and the toughness will decrease. Also, M
Addition of a large amount of Mo inhibits hot workability, so the amount of Mo added was set to 0.3 to 1.5%. Preferably 0.7-1.
It is 3%.
■Ｖ：Ｖは炭化物を生成するとともにＮと化合してＶＮ
がフェライト地中に析出し、クリープ破断強度を著しく
高める効果がある。その効果は０．０５％以上で現われ
、０．３５％を越えると溶接割れ感受性を高め、溶接性
が劣化する。従って０．０５〜０．３５％とした。好ま
しくは０．１５〜３％である。■V: V generates carbide and combines with N to form VN
precipitates in the ferrite ground and has the effect of significantly increasing creep rupture strength. This effect appears when the content exceeds 0.05%, and when the content exceeds 0.35%, the susceptibility to weld cracking increases and weldability deteriorates. Therefore, it was set at 0.05 to 0.35%. Preferably it is 0.15 to 3%.
■Ｎｂ：Ｎｂは炭窒化物を生成し、短時間側のクリープ
破断強度を高め、■との複合添加によってＶ炭窒化物を
微細に、また良好な分散状態で析出させる効果があり、
その効果は０．０１％以上で現われる。また、０．１２
％を越えて添加してもその効果は飽和し、かえって長時
間側のクリープ破断強度を低下させる原因となる。また
、多量添加した場合には溶接性を低下させる。従って、
０．０１〜０．■２％とした。好ましくは０．０１〜０
．０５％である。■Nb: Nb generates carbonitrides, increases creep rupture strength on the short-time side, and when combined with ■, has the effect of precipitating V carbonitrides finely and in a well-dispersed state.
The effect appears at 0.01% or more. Also, 0.12
Even if it is added in excess of 5%, the effect will be saturated and it will cause a decrease in creep rupture strength on the long-term side. Moreover, when added in a large amount, weldability is reduced. Therefore,
0.01~0. ■2%. Preferably 0.01-0
．． 05%.
１１１１ＤＮ ： ＮはＣの代替元素としての役割りを
果すとともに、■及びＮｂなどと窒化物あるいは炭窒化
物を形成し、クリープ破断強度を著しく上昇させる。そ
の効果は０．０１％未満では不十分であり、０．０５％
を越えて添加すると焼入れ性が高くなり、溶接性を阻害
するので、０．０１〜０．０５％とした。好ましくは０
．Ｏｌ〜０．０３％である。1111DN: N acts as a substitute element for C, and also forms nitrides or carbonitrides with ■ and Nb, significantly increasing creep rupture strength. The effect is insufficient below 0.01%, and 0.05%
If it is added in an amount exceeding 0.01 to 0.05%, hardenability increases and weldability is inhibited. Preferably 0
．． Ol~0.03%.
■ＷＯＷは上記成分に加えて添加することにより、Ｍｏ
の添加量を減じ、またＭＯとともにフェライト地に固溶
して高温強度を著しく高める。■WOW is made by adding Mo
The amount of addition of MO is reduced, and the high-temperature strength is significantly increased by solid solution in the ferrite matrix along with MO.
その効果は０．５％未満では十分ではなく、また、２．
４％を越えて添加した場合、熱間加工性を阻害し靭性が
低下する。従って０．５〜２．４％とした。好ましくは
０．７〜１．８％である。The effect is not sufficient if it is less than 0.5%, and 2.
When added in excess of 4%, hot workability is inhibited and toughness is reduced. Therefore, it was set at 0.5 to 2.4%. Preferably it is 0.7 to 1.8%.
■Ｂ二Ｂは粒界の強度を高める元素であり、クリープ破
断強度及び延性を上昇させる。その効果は０．０００５
％未満では不十分であり、０．０１５％を越えて添加し
た場合、熱間加工性を阻害するとともに常温強度が高く
なり加工性を低下させる。従って０．０００５〜０．０
１５％とした。好ましくは０．００１〜０、００５％で
ある。(2) B B is an element that increases the strength of grain boundaries and increases creep rupture strength and ductility. The effect is 0.0005
If it is less than 0.015%, it is insufficient, and if it is added in excess of 0.015%, it inhibits hot workability and increases room temperature strength, reducing workability. Therefore 0.0005~0.0
It was set at 15%. Preferably it is 0.001 to 0.005%.
＠Ａｌ ： Ａｌは脱酸剤としても有効であり、かつ低
温靭性を向上させる効果があるが、０．０５％を越えて
多量に含有させると結晶粒を小さくし、クリープ破断強
度を低下させる。従って０．０５％以下とした。好まし
くは０．０１５％以下である。@Al: Al is effective as a deoxidizing agent and has the effect of improving low-temperature toughness, but if it is contained in a large amount exceeding 0.05%, it reduces the size of crystal grains and reduces creep rupture strength. Therefore, the content was set at 0.05% or less. Preferably it is 0.015% or less.
ＱＴｉ：Ｔｉは炭化物を形成し、クリープ破断強度を上
昇させるが、その効果は０．０５％未満では十分ではな
く、また０、２％を越えて添加した場合、低温靭性を低
下させる。従って０．０５〜０．２％とした。好ましく
は０．０５〜０．１％である。QTi: Ti forms carbides and increases creep rupture strength, but this effect is not sufficient if it is less than 0.05%, and if it is added in excess of 0.2%, it reduces low temperature toughness. Therefore, it was set at 0.05 to 0.2%. Preferably it is 0.05 to 0.1%.
上記のＷ、 Ｂ、 ＡＩ及びＴｉは本発明鋼における
フェライトを安定化する効果があり、フェライト地の強
化析出物ＶＮの析出を促し、間接的に高温強度（クリー
プ破断強度）を高めるのに役立つ。本発明鋼では必要に
応じて、これらＷ。The above W, B, AI and Ti have the effect of stabilizing the ferrite in the steel of the present invention, promote the precipitation of strengthening precipitates VN in the ferrite base, and indirectly help to increase the high temperature strength (creep rupture strength). . In the steel of the present invention, these W may be used as necessary.
Ｂ、ＡＩ及びＴ１を上記範囲内で１種以上を含有させる
。One or more of B, AI and T1 are contained within the above range.
次に、本発明鋼の熱処理条件について説明する。Next, the heat treatment conditions for the steel of the present invention will be explained.
上記成分の鋼をオーステナイト化温度以上に加熱し、オ
ーステナイト化温度からの冷却途中で圧延または鍛造を
行ない、Ａｒ＋直上まで連続的な塑性加工が施工される
が、微量添加された■やＮｂが炭窒化物として微細析出
し、それが再結晶粒の粗大化を阻止して細粒組織が得ら
れる。Steel with the above components is heated above the austenitizing temperature, and rolled or forged during cooling from the austenitizing temperature, and continuous plastic working is performed up to just above Ar+. It precipitates finely as nitrides, which prevents recrystallized grains from becoming coarser, resulting in a fine grain structure.
また、この細粒中には微細炭窒化物が多数析出している
ために、細粒でありながらクリープ破断強度の低下を生
じさせない。Moreover, since many fine carbonitrides are precipitated in these fine grains, the creep rupture strength does not decrease even though they are fine grains.
以上のように、Ｍｏ、 Ｗによる固溶強化とＶ。As mentioned above, solid solution strengthening by Mo and W and V.
Ｎｂによる析出強化が得られるように成分設計した鋼を
オーステナイト化温度からＡｒ＋直上の温度まで連続し
て塑性加工することによって、Ｖ。By continuously plastic working steel whose composition is designed to obtain precipitation strengthening by Nb from the austenitizing temperature to a temperature just above Ar+, V.
Ｎｂの炭窒化物が微細に析出した細粒鋼が得られる。こ
のような化学成分と組織は鋼の機械的性質、特に靭性の
改善と溶接熱影響部の特性劣化を阻止する上で極めて効
果的である。A fine-grained steel in which Nb carbonitrides are finely precipitated is obtained. Such chemical composition and structure are extremely effective in improving the mechanical properties of steel, especially toughness, and preventing deterioration of the properties of the weld heat affected zone.
以下、本発明の実施例をあげ、本発明の効果を立証する
。Examples of the present invention will be given below to demonstrate the effects of the present invention.
第１表に示す化学成分の供試材を１０チヤージ、大気中
高周波溶解炉により各々５０ｋｇ溶製した後、９５０〜
１１００℃の範囲で熱間鍛造し、断面が４０Ｘ２０ｍｍ
の棒とした後、１０５０℃ＡＣ＋７５０℃ＡＣの熱処理
を施した従来鋼を作製するとともに、９５０〜１１００
℃の範囲で素鍛造を行ない、断面が８０Ｘ４０ｍｍの板
を作り、室温に冷却した。その後この板を再度１１５０
℃に加熱し、圧延機によって、７８０℃の温度に冷却す
るまで連続して圧延し、断面が１７０Ｘ１５ｍｍの本発
明による板を製作した。After melting 10 charges of test materials with the chemical components shown in Table 1 and 50 kg each in an atmospheric high-frequency melting furnace, 950 ~
Hot forged at 1100℃, cross section 40x20mm
After making a bar of
Bare forging was performed in the temperature range of 0.degree. C. to produce a plate with a cross section of 80 mm x 40 mm, and the plate was cooled to room temperature. After that, change this board again to 1150
℃ and continuously rolled by a rolling mill until cooled to a temperature of 780° C. to produce a plate according to the invention with a cross section of 170×15 mm.
これらの供試材を用いてシャルピー衝撃試験を実施する
とともに、クリープ破断強度を行なって６００℃×１０
３時間及び×１０４時間の破断強度を求めた。Charpy impact tests were carried out using these test materials, and creep rupture strength was also measured at 600°C x 10
The breaking strength was determined for 3 hours and ×104 hours.
さらに代表的な供試材を用いて溶接継手を作製し、７１
５℃でＡ時間応力除去焼鈍を行なった後に断面硬さ分布
を測定した。Furthermore, welded joints were made using representative test materials, and 71
After performing stress relief annealing at 5° C. for A time, the cross-sectional hardness distribution was measured.
第２表は従来鋼と本発明鋼の０℃シャルピー吸収エネル
ギーとクリープ破断強度を比較して示した。これから明
らかなようにクリープ破断強度には大差はみられなかっ
たが、シャルピー吸収エネルギーには大きな差がみられ
、本発明鋼では大幅な改善がみられた。Table 2 shows a comparison of the 0°C Charpy absorbed energy and creep rupture strength of the conventional steel and the steel of the present invention. As is clear from this, there was no significant difference in creep rupture strength, but there was a large difference in Charpy absorbed energy, and a significant improvement was seen in the steel of the present invention.
シャルピー吸収エネルギーの差は第１図に示した遷移カ
ーブからもより明らかである。すなわち、本発明鋼は遷
移温度が低下して靭性が改善され、０℃で優れたシャル
ピー吸収エネルギーを示すことが分る。The difference in Charpy absorbed energy is also clearer from the transition curve shown in FIG. That is, it can be seen that the steel of the present invention has a lower transition temperature, improved toughness, and exhibits excellent Charpy absorbed energy at 0°C.
第２図は溶接継手の断面において硬さ分布を測定したも
のである。本発明鋼の溶接熱影響部の硬さは母材原質部
のそれとほとんど差異がなく、また、顕著な軟化層も認
められなかったが、従来鋼では溶接熱影響部の細粒化域
において軟化層が発生し、母材原質部にビッカーズ硬さ
で約Ｈｖ１５の軟化がみられた。Figure 2 shows the hardness distribution measured in the cross section of the welded joint. The hardness of the weld heat-affected zone of the inventive steel was almost the same as that of the base material, and no noticeable softened layer was observed, but in the conventional steel, the hardness of the weld heat-affected zone was fine-grained. A softened layer was generated, and a softening of about Hv15 in terms of Vickers hardness was observed in the original base material.
以上のように、本発明の第２発明の鋼は靭性の改善及び
溶接熱影響部の特性変化防止の面から優れた効果を発揮
することが確認された。As described above, it was confirmed that the steel of the second invention of the present invention exhibits excellent effects in terms of improving toughness and preventing changes in properties of the weld heat affected zone.
本発明によれば、従来のオーステナイト鋼、ＱＣｒ鋼、
１２Ｃｒ鋼、１〜２ ’Ａ Ｃｒ鋼、１．０％未満のＣ
ｒを含有する鋼などにおける欠点が解消され、溶接熱影
響部の軟化の程度を軽減し、さらに母地のシャルピー衝
撃値を改善した上で、約６００℃までオーステナイト系
ステンレス鋼、高強度ＱＣｒ鋼、１２Ｃｒ鋼に代えて使
用できる鋼が提供される。According to the present invention, conventional austenitic steel, QCr steel,
12Cr steel, 1-2'A Cr steel, less than 1.0% C
The drawbacks of steels containing r are eliminated, the degree of softening of the weld heat affected zone is reduced, and the Charpy impact value of the base material is improved, and the austenitic stainless steel and high-strength QCr steel can be used up to approximately 600℃. , 12Cr steel is provided.
【図面の簡単な説明】
第１図は本発明鋼と鉄鋼と同じ化学成分を含む従来鋼の
遷移カーブの比較をあられす図表、第２図は同じく本発
明鋼と鉄鋼と同じ化学成分を含む従来鋼の溶接継手につ
いての断面硬さを比較した図表である。
代 理 人 内 １） 明、
代 理 人 萩 原 亮代 理 人
安 西 篤 夫第１
図
度
（°Ｃ）
距
離[Brief explanation of the drawings] Figure 1 is a chart comparing the transition curves of the steel of the present invention and conventional steel, which have the same chemical composition as steel, and Figure 2 shows the comparison of the transition curves of the steel of the present invention and conventional steel, which also have the same chemical composition as steel. It is a chart comparing the cross-sectional hardness of conventional steel welded joints. Among the agents: 1) Akira;
Representative Ryoyo Hagiwara
Atsuo Anzai 1st Degree (°C) Distance
Claims (1)
、Ｍｎ：０．２〜１％、Ｐ≦０．０３％、Ｓ≦０．０３
％、Ｎｉ≦０．８％、Ｃｒ：０．７〜３％、Ｍｏ：０．
３〜１．５％、Ｖ：０．０５〜０．３５％、Ｎｂ：０．
０１〜０．１２％、Ｎ：０．０１〜０．０５％を含み、
あるいは更にＷ：０．５〜２．４％、Ｂ：０．０００５
〜０．０１５％、Ａｌ≦０．０５％、Ｔｉ：０．０５〜
０．２％の１種以上を含む残部Ｆｅ及び不可避の不純物
からなる鋼を、オーステナイト化温度以上に加熱したの
ち圧延または鍛造し、それを冷却途中あるいは一旦Ａｃ
＿１温度以下に冷却したのち、再度オーステナイト化温
度以上に加熱して冷却途中のＡｒ＿３よりも高い温度か
らＡｒ＿１直上の温度域で連続して圧延または鍛造して
なることを特徴とする高強度低合金耐熱鋼。(1) In weight%, C: 0.03-0.12, Si≦1%
, Mn: 0.2-1%, P≦0.03%, S≦0.03
%, Ni≦0.8%, Cr: 0.7-3%, Mo: 0.
3-1.5%, V: 0.05-0.35%, Nb: 0.
01 to 0.12%, N: 0.01 to 0.05%,
Or further W: 0.5-2.4%, B: 0.0005
~0.015%, Al≦0.05%, Ti:0.05~
Steel consisting of the balance Fe containing 0.2% or more of one kind and unavoidable impurities is heated to a temperature higher than the austenitizing temperature, then rolled or forged, and then heated during cooling or once in AC.
A high-strength low alloy characterized by being cooled to a temperature below _1, then heated again to a temperature above the austenitizing temperature, and then continuously rolled or forged in a temperature range from a temperature higher than Ar_3 during cooling to just above Ar_1. Heat resistant steel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1221699A JP2659814B2 (en) | 1989-08-30 | 1989-08-30 | Manufacturing method of high strength low alloy heat resistant steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1221699A JP2659814B2 (en) | 1989-08-30 | 1989-08-30 | Manufacturing method of high strength low alloy heat resistant steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0387333A true JPH0387333A (en) | 1991-04-12 |
| JP2659814B2 JP2659814B2 (en) | 1997-09-30 |
Family
ID=16770892
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1221699A Expired - Fee Related JP2659814B2 (en) | 1989-08-30 | 1989-08-30 | Manufacturing method of high strength low alloy heat resistant steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2659814B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0835946A1 (en) * | 1996-10-09 | 1998-04-15 | Mitsubishi Heavy Industries, Ltd. | Weldable low-chromium ferritic cast steel, having excellent high-temperature strength |
| CN103320696A (en) * | 2013-06-06 | 2013-09-25 | 济钢集团有限公司 | Low-alloy heat-resistant steel plate and manufacturing method thereof |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01316441A (en) * | 1988-06-14 | 1989-12-21 | Nkk Corp | Heat-resistant steel having excellent toughness |
-
1989
- 1989-08-30 JP JP1221699A patent/JP2659814B2/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01316441A (en) * | 1988-06-14 | 1989-12-21 | Nkk Corp | Heat-resistant steel having excellent toughness |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0835946A1 (en) * | 1996-10-09 | 1998-04-15 | Mitsubishi Heavy Industries, Ltd. | Weldable low-chromium ferritic cast steel, having excellent high-temperature strength |
| CN103320696A (en) * | 2013-06-06 | 2013-09-25 | 济钢集团有限公司 | Low-alloy heat-resistant steel plate and manufacturing method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2659814B2 (en) | 1997-09-30 |
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