JP2008121068A - Steel material for iron shell of converter - Google Patents
Steel material for iron shell of converter Download PDFInfo
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- JP2008121068A JP2008121068A JP2006306661A JP2006306661A JP2008121068A JP 2008121068 A JP2008121068 A JP 2008121068A JP 2006306661 A JP2006306661 A JP 2006306661A JP 2006306661 A JP2006306661 A JP 2006306661A JP 2008121068 A JP2008121068 A JP 2008121068A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 34
- 239000010959 steel Substances 0.000 title claims abstract description 34
- 239000000463 material Substances 0.000 title claims abstract description 17
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title abstract description 17
- 229910052742 iron Inorganic materials 0.000 title abstract description 6
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 10
- 239000012535 impurity Substances 0.000 claims abstract description 7
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 6
- 239000000203 mixture Substances 0.000 claims abstract description 5
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 5
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 4
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 4
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 4
- 229910052796 boron Inorganic materials 0.000 claims abstract description 3
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 3
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 3
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 3
- 229910052717 sulfur Inorganic materials 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 229910052760 oxygen Inorganic materials 0.000 claims description 2
- 238000005336 cracking Methods 0.000 abstract description 41
- 230000035945 sensitivity Effects 0.000 abstract description 13
- 238000003466 welding Methods 0.000 abstract description 8
- 229910052802 copper Inorganic materials 0.000 abstract description 2
- 229910052750 molybdenum Inorganic materials 0.000 abstract description 2
- 230000000694 effects Effects 0.000 description 9
- 238000004519 manufacturing process Methods 0.000 description 8
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 6
- 230000001965 increasing effect Effects 0.000 description 6
- 238000009826 distribution Methods 0.000 description 3
- 238000005098 hot rolling Methods 0.000 description 3
- 229940045657 oxycide Drugs 0.000 description 3
- 229910052761 rare earth metal Inorganic materials 0.000 description 3
- 230000032683 aging Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000009863 impact test Methods 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 238000009864 tensile test Methods 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 229910019582 Cr V Inorganic materials 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 101100527115 Picea mariana RPL31 gene Proteins 0.000 description 1
- 101100257123 Strongylocentrotus purpuratus SM50 gene Proteins 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 238000010606 normalization Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
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- Heat Treatment Of Steel (AREA)
Abstract
Description
本発明は転炉鉄皮用鋼材に関し、特に、溶接部の再熱割れ感受性、低温割れ感受性が低く、製造や溶接補修が容易なものに関する。 The present invention relates to a steel material for a converter iron core, and particularly relates to a material having low reheat cracking susceptibility and low temperature cracking susceptibility of a welded portion and easy to manufacture and repair welding.
転炉鉄皮用鋼材は、鉄皮が溶損したり、変形したりした場合、溶接により補修されるため、ＳＭ４００等Ｃｅｑや、低温割れ感受性が低いものが使用されていたが、近年、高操業を維持するため、高温の使用状態で長寿命を有することが求められ、Ｍｏが添加されたＳＢ４５０Mなど高温クリープ強度に優れるものが使用されるようになった。 Since the steel for converter cores is repaired by welding when the cores are melted or deformed, SM400 and other low-crack susceptibility materials have been used in recent years. In order to maintain the above, it has been required to have a long life in a high temperature use state, and those having excellent high temperature creep strength such as SB450M to which Mo is added have been used.
例えば、特許文献１は、転炉鉄皮用厚鋼板およびその製造方法に関し、中常温圧力容器用高強度鋼はＳＢ４２やＳＭ５０などより高温強度が優れるものの、経年劣化により脆性亀裂を生じることがあるところ、Ｍｏ，Vの複合添加で高温強度を確保し、低Ｐｃｍで低温割れを防止し、更に微細組織とすることで高温時効による脆化を防止した転炉鉄皮用厚鋼板が記載されている。 For example, Patent Document 1 relates to a thick steel plate for a converter iron shell and a method for manufacturing the same, and high strength steel for medium-temperature pressure vessels has superior high-temperature strength than SB42 and SM50, but may cause brittle cracks due to aging. However, a thick steel plate for converter cores is described in which high-temperature strength is secured by the combined addition of Mo and V, low-temperature cracking is prevented at a low Pcm, and further embrittlement due to high-temperature aging is prevented by forming a microstructure. Yes.
特許文献２は、鉄皮などに用いられる高温強度に優れた炭素鋼の製造方法に関し、Ｃｒ−Ｍｏ成分系の鋼をＡｒ３よりも高い温度からＡｒ１直上まで連続して熱間圧延することにより、４５０℃における高温強度と長時間クリープ特性に優れるものとすることが記載されている。 Patent Document 2 relates to a method for producing a carbon steel excellent in high-temperature strength used for an iron skin or the like, by continuously hot rolling a Cr-Mo component steel from a temperature higher than Ar3 to directly above Ar1. It describes that it is excellent in high-temperature strength at 450 ° C. and long-term creep characteristics.
特許文献３は、高温強度に優れ溶接性の良好な低合金耐熱鋼に関し、Ｃｕ−Ｎｉ−Ｍｏ−Ｃｒ−Ｖ系成分を基本成分とし、Ａｌ，Ｎｂ，Ｔｉを選択成分として添加する際、これら元素と鋼中Ｎ量で規定される、窒化物生成に関するパラメータ式が特定範囲となるように添加量を調整し、３００〜４５０℃で優れた高温強度を確保することが記載されている。
ところで、転炉用鉄皮は溶接により製造され、製造後ＳＲ処理されるため、低温割れ感受性が低いことの他に、ＳＲ割れが生じないことが必要で、鉄皮用鋼材には、高温強度、高温クリープ特性の他に上記優れた溶接部の特性を備えることが要求される。 By the way, since the iron core for converters is manufactured by welding and is subjected to SR treatment after manufacturing, it is necessary that SR cracking does not occur in addition to low susceptibility to low temperature cracks. In addition to the high-temperature creep characteristics, it is required to have the above-described excellent weld characteristics.
そこで、本発明では、上述した諸特性に優れる転炉鉄皮用鋼材を提供することを目的とする。 Accordingly, an object of the present invention is to provide a steel material for a converter core that is excellent in the above-described various characteristics.
本発明者等は、上記課題を解決するため鋭意検討を行い、成分設計において下記の指導原理を得た。
（１）４００℃を超える高温でのクリープ強度を高めて、クリープ変形を抑えるためＭｏを０．２％以上添加する。更に必要に応じてＮｂ，Ｖなどを添加する。
（２）鉄皮製造時の溶接低温割れを防止するため、Ｐｃｍを０．２２以下とする。
（３）鉄皮製造中の割れ防止の観点から、Ｐ，Ｓ，Ｎ，Ｏを低く制限するとともに、ＰＳＲを０未満に低く制限し、且つＣａを添加する。これにより、製造時の溶接部における再熱割れおよび使用中、長期間使用後の溶接部の延性低下割れを防止する。
The inventors of the present invention conducted intensive studies in order to solve the above-described problems, and obtained the following guiding principle in component design.
(1) Mo is added in an amount of 0.2% or more in order to increase the creep strength at a high temperature exceeding 400 ° C. and suppress creep deformation. Further, Nb, V, etc. are added as necessary.
(2) Pcm is set to 0.22 or less in order to prevent welding cold cracking during the manufacture of the iron skin.
(3) From the viewpoint of preventing cracking during the production of the iron skin, P, S, N, and O are limited to be low, PSR is limited to be less than 0, and Ca is added. This prevents reheat cracking in the welded part during manufacture and ductile deterioration cracking of the welded part after long-term use during use.
本発明は上記指導原理に更に検討を加えてなされたもので、すなわち、本発明は、
１．質量％で、Ｃ：０．０３〜０．１５％、Ｓｉ：０．０１〜０．５０％、Ｍｎ：０．３０〜１．５０％、Ｐ≦０．０１５％、Ｓ≦０．００３％、Ｍｏ：０．２〜０．６％、更にＣａ：０．０００３〜０．００５％、Ｍｇ：０．０００５〜０．００５％、ＲＥＭ：０．００２〜０．０２％の一種または二種以上を含有し、ｓｏｌ．Ａｌ≦０．０４％、Ｎ≦０．００６％、Ｏ≦０．００３％、Ｐｃｍ≦０．２２％、ＰＳＲ＜０，残部Ｆｅおよび不可避的不純物からなる転炉鉄皮用鋼材。
但し、Ｐｃｍ＝C＋Ｓｉ／３０＋Ｍｎ／２０＋Ｃｕ／２０＋Nｉ／６０＋Ｃｒ／２０＋Ｍｏ／１５＋Ｖ／１０＋５Ｂ
ＰＳＲ＝Ｃｒ＋３．３Ｍｏ＋１０V＋Ｃｕ＋７Nｂ＋５Ｔｉ−２
各式において元素は含有量（質量％）とする。
２．１記載の成分組成に更に、Ｃｕ：０．０３〜０．５％、Ｎｉ：０．０３〜０．５％、Ｃｒ：０．０３〜０．７％、Ｖ：０．００５〜０．０５％、Ｔｉ：０．００５〜０．０５％、Ｎｂ：０．００５〜０．０３％、Ｂ：０．０００３〜０．００２％の一種又は二種以上を含有することを特徴とするＰｃｍ≦０．２２％、ＰＳＲ＜０，残部Ｆｅおよび不可避的不純物からなる転炉鉄皮用鋼材。
但し、Ｐｃｍ＝C＋Ｓｉ／３０＋Ｍｎ／２０＋Ｃｕ／２０＋Nｉ／６０＋Ｃｒ／２０＋Ｍｏ／１５＋Ｖ／１０＋５Ｂ
ＰＳＲ＝Ｃｒ＋３．３Ｍｏ＋１０V＋Ｃｕ＋７Nｂ＋５Ｔｉ−２
各式において元素は含有量（質量％）とする。
The present invention has been made by further studying the above guiding principle, that is, the present invention
1. In mass%, C: 0.03 to 0.15%, Si: 0.01 to 0.50%, Mn: 0.30 to 1.50%, P ≦ 0.015%, S ≦ 0.003% , Mo: 0.2 to 0.6%, Ca: 0.0003 to 0.005%, Mg: 0.0005 to 0.005%, REM: 0.002 to 0.02% Containing sol. Al ≦ 0.04%, N ≦ 0.006 %, O ≦ 0.003%, Pcm ≦ 0.22%, P SR <0, the converter steel skins steel material and the balance Fe and unavoidable impurities.
However, Pcm = C + Si / 30 + Mn / 20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B
P SR = Cr + 3.3Mo + 10V + Cu + 7Nb + 5Ti-2
In each formula, the element is the content (% by mass).
In addition to the component composition described in 2.1, Cu: 0.03-0.5%, Ni: 0.03-0.5%, Cr: 0.03-0.7%, V: 0.005-0 0.05%, Ti: 0.005 to 0.05%, Nb: 0.005 to 0.03%, B: 0.0003 to 0.002%, or one or more types A steel material for a converter core comprising Pcm ≦ 0.22%, P SR <0, the balance Fe and inevitable impurities.
However, Pcm = C + Si / 30 + Mn / 20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B
P SR = Cr + 3.3Mo + 10V + Cu + 7Nb + 5Ti-2
In each formula, the element is the content (% by mass).
本発明によれば、１．設備の長寿命化、２．３．更に溶損、変形が生じた場合、溶接補修が容易であること、が達成され産業上極めて有用である。 According to the present invention: Longer equipment life 2.3. Further, when melting damage or deformation occurs, it is possible to easily repair the weld, which is extremely useful in the industry.
以下、本発明の成分限定理由について詳細に説明する。尚、％は質量％とする。
Ｃ
Ｃは転炉鉄皮用鋼材として強度及び靭性を確保するため、０．０３％以上必要であるが、増加に伴い靭性や溶接低温割れ性を増大させるため、０．１５％を上限とする。
Hereinafter, the reasons for limiting the components of the present invention will be described in detail. Note that% is mass%.
C
C is required to be 0.03% or more in order to ensure strength and toughness as a steel material for converter cores. However, 0.15% is made the upper limit in order to increase the toughness and weld cold cracking property with the increase.
Ｓｉ
Ｓｉは強度の確保に有効であるが、靭性を劣化させるため、０．０１％以上、０．５０％以下とする。
Si
Si is effective for securing the strength, but in order to deteriorate the toughness, it is set to 0.01% or more and 0.50% or less.
Ｍｎ
Ｍｎは強度、靭性を増加させるのに有効であるが、溶接性を劣化させるため、０．３０％以上、１．５０％以下とする。
Mn
Mn is effective in increasing the strength and toughness, but in order to deteriorate the weldability, it is 0.30% or more and 1.50% or less.
Ｐ、Ｓ
Ｐ、Ｓは本発明は不純物で、Ｐは焼き戻し脆性を助長し、靭性を損ねると共に再熱割れ感受性を高めるため、０．０１５％以下とする。Ｓは再熱割れ感受性を高めるため、０．００３％以下とする。
P, S
P and S are impurities in the present invention, and P promotes temper brittleness, impairs toughness, and increases reheat cracking sensitivity, so that it is made 0.015% or less. In order to increase the reheat cracking sensitivity, S is made 0.003% or less.
Ｍｏ
Ｍｏは高温強度、クリープ強度の向上に有効なため、その作用効果を得るため、０．２％以上添加する。一方、０．６％を超えて添加した場合、溶接性を劣化させ、経済性も損なうため、０．２％以上、０．６％以下とする。
Mo
Since Mo is effective for improving the high temperature strength and creep strength, 0.2% or more is added in order to obtain the effect. On the other hand, if added over 0.6%, the weldability deteriorates and the economic efficiency is also impaired, so the content is made 0.2% or more and 0.6% or less.
Ｃａ、ＲＥＭ，Ｍｇの一種または二種以上
Ｃａは硫化物（サルファイド）形成元素で、鋼中の固溶Ｓを固定し、再熱割れ感受性を改善する。また、酸化物（オキシサイド）系介在物の分布を制御し、再熱割れ感受性を改善するために０．０００３％以上添加する。一方、０．００５％を超え添加した場合は、粗大な介在物が増加し、靭性を劣化させるとともに再熱割れが生じやすくなるために０．００５％以下とする。
One or more of Ca, REM, and Mg are sulfide (sulfide) -forming elements that fix solute S in steel and improve reheat cracking sensitivity. Further, 0.0003% or more is added in order to control the distribution of oxide (oxycide) inclusions and improve the reheat cracking sensitivity. On the other hand, if added over 0.005%, coarse inclusions increase, which deteriorates toughness and easily causes reheat cracking, so the content is made 0.005% or less.
ＲＥＭ
ＲＥＭは原子番号が５７番〜７１番までの希土類元素（ＲＥＭ）で、Ｃａ、Ｍｇと同様に強硫化物（サルファイド）生成元素であり、鋼中の固溶Ｓの固定や酸化物（オキシサイド）系介在物の分布状態を制御して再熱割れ感受性を低下させるため、添加する場合は、０．００２％以上とする。一方、０．０２％を超え添加した場合は、粗大な介在物が増加し、靭性を劣化させるとともに再熱割れが生じやすくなるために０．０２％以下とする。
REM
REM is a rare earth element (REM) with atomic numbers from 57 to 71 and is a strong sulfide (sulfide) -forming element like Ca and Mg. ) In order to control the distribution of system inclusions and reduce reheat cracking sensitivity, when added, the content is made 0.002% or more. On the other hand, if over 0.02% is added, coarse inclusions increase, which deteriorates toughness and easily causes reheat cracking, so the content is made 0.02% or less.
Ｍｇ
Ｍｇは強硫化物（サルファイド）生成元素であり、鋼中の固溶Ｓの固定や酸化物（オキシサイド）系介在物の分布状態を制御して再熱割れ感受性を低下させるため、添加する場合は、０．０００５％以上とする。一方、０．００５％を超え添加した場合は、粗大な介在物が増加し、靭性を劣化させるとともに再熱割れが生じやすくなるために０．００５％以下とする。
Mg
Mg is a strong sulfide (sulfide) -forming element, and is added to reduce the reheat cracking susceptibility by controlling the solid solution S fixation in steel and the distribution of oxide (oxycide) inclusions. Is 0.0005% or more. On the other hand, if added over 0.005%, coarse inclusions increase, which deteriorates toughness and easily causes reheat cracking, so the content is made 0.005% or less.
ｓｏｌ．Ａｌ
ｓｏｌ．Ａｌは脱酸材として添加され、また、焼きならし時などのＮの固定にも有効であり、靭性も向上させるが、溶接部の再熱割れ感受性や高温延性を低下させるため、０．０４％以下とする。
sol. Al
sol. Al is added as a deoxidizing material, and is also effective for fixing N during normalization and improves toughness, but reduces the reheat cracking susceptibility and high temperature ductility of the welded portion. % Or less.
Ｎ
Nは過度に含有すると靭性を劣化させるため、０．００６％以下とする。
N
If N is excessively contained, the toughness deteriorates, so 0.006% or less.
Ｏ
Ｏは酸化物（オキシサイド）系介在物の生成により、延靭性や溶接性を低下させ、再熱割れ感受性を増大させる。また、Ｃａ添加の効果を損なわないように０．００３％以下とする。
O
O reduces the toughness and weldability due to the formation of oxide (oxycide) inclusions, and increases the reheat cracking sensitivity. Moreover, it is 0.003% or less so as not to impair the effect of Ca addition.
Ｐｃｍ
Ｐｃｍ（＝C＋Ｓｉ／３０＋Ｍｎ／２０＋Ｃｕ／２０＋Nｉ／６０＋Ｃｒ／２０＋Ｍｏ／１５＋Ｖ／１０＋５Ｂ、元素は含有量（質量％））は、溶接部の低温割れを防止するため、０．２２％以下とする。
Pcm
Pcm (= C + Si / 30 + Mn / 20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B, element content (mass%)) is set to 0.22% or less in order to prevent cold cracking of the weld.
ＰＳＲ
ＰＳＲ（＝Ｃｒ＋３．３Ｍｏ＋１０V＋Ｃｕ＋７Nｂ＋５Ｔｉ−２、元素は含有量（質量％））は溶接部のＳＲ割れを防止するため、０未満とする。
P SR
P SR (= Cr + 3.3Mo + 10V + Cu + 7Nb + 5Ti-2, element content (% by mass)) is set to less than 0 in order to prevent SR cracking of the weld.
以上が本発明の基本成分組成であるが、更に特性を向上させる場合、Ｃｕ，Ｎｉ，Cｒ、Ｖの一種または二種以上を添加する。 The above is the basic component composition of the present invention, but when further improving the characteristics, one or more of Cu, Ni, Cr, and V are added.
Ｃｕ
Ｃｕは焼入れ性を高め、また固溶強化元素として強度を高めるため、その作用効果を得る場合、０．０３％以上添加するが、過剰に添加すると、再熱割れ感受性を高め、またクリープ延性や熱間加工性を低下さえるため、添加する場合は、０．０３％以上、０．５％以下とする。
Cu
Cu increases the hardenability and increases the strength as a solid solution strengthening element. When obtaining its effect, 0.03% or more is added. However, when excessively added, the reheat cracking sensitivity is increased, and creep ductility and In order to reduce the hot workability, when added, the content is made 0.03% or more and 0.5% or less.
Ｎｉ
Ｎｉは焼入れ性を向上させると共に靭性向上にも有効であるので、その作用効果を得る場合、０．０３％以上添加するが、過剰に添加すると再熱割れ感受性を高め、経済性も低下するので、添加する場合は０．０３％以上、０．５％以下とする。
Ni
Ni is effective in improving hardenability and improving toughness, so when obtaining its effect, 0.03% or more is added. However, if excessively added, reheat cracking susceptibility is increased and economic efficiency is also reduced. When added, the content is 0.03% or more and 0.5% or less.
Ｃｒ
Ｃｒは常温強度及び高温強度を高めるため有効であるので、その作用効果を得る場合、０．０３％以上添加するが、過剰に添加すると溶接性を劣化させるので、添加する場合は、０．０３％以上、０．７％以下とする。
Cr
Since Cr is effective for increasing the normal temperature strength and the high temperature strength, when obtaining its effect, 0.03% or more is added. However, when excessively added, the weldability is deteriorated. % To 0.7%.
Ｖ
Ｖは炭化物生成元素で、常温強度および高温強度、クリープ破断強度を向上させるので、その作用効果を得る場合、０．００５％以上添加するが、過剰に添加すると再熱割れ感受性を高めるので、添加する場合は０．００５％以上、０．０５％以下とする。
V
V is a carbide-forming element, and improves normal temperature strength, high temperature strength, and creep rupture strength. Therefore, when obtaining its effect, 0.005% or more is added, but if added excessively, reheat cracking susceptibility is increased. When it is, it is made 0.005% or more and 0.05% or less.
Ｎｂ
Ｎｂは安定な炭窒化物生成元素であり、強度および高温強度、クリープ破断強度を上昇させることが出来るが、過剰に含有させると靭性や溶接性を損ねるとともに、再熱割れ感受性を高めるので、添加する場合は０．００５〜０．０３％以下とする。
Nb
Nb is a stable carbonitride-forming element, which can increase strength, high-temperature strength, and creep rupture strength, but adding excessively impairs toughness and weldability and increases reheat cracking susceptibility. When it does, it is made into 0.005 to 0.03% or less.
Ｂ
Ｂは焼入れ性を高め、強度を向上させるが、過剰に添加するとその効果が飽和し、再熱割れ感受性を著しく高めるため、添加する場合は、０．０００３〜０．００２％とする。
B
B enhances hardenability and improves strength, but if added in excess, its effect is saturated and reheat cracking sensitivity is remarkably increased. Therefore, when B is added, the content is made 0.0003 to 0.002%.
Ｔｉ
Ｔｉは強窒化物形成元素で、細粒化により靭性を向上させる。また、Ｂを添加した場合、Ｎを固定してＢの焼入れ性向上効果を高める効果を有するため、添加する場合は、０．００５％以上、０．０５％以下とする。
Ti
Ti is a strong nitride-forming element and improves toughness by refining. Further, when B is added, it has an effect of fixing N and enhancing the hardenability improvement effect of B. Therefore, when B is added, the content is made 0.005% to 0.05%.
尚、Ｓｎ，Ａｓ，Ｓｂなどの不純物元素は再熱割れ感受性およびクリープ脆化感受性を増大させるため、夫々０．０１％以下、好ましくは０．００５％以下とすることが好ましい。 In addition, in order to increase the reheat cracking susceptibility and creep embrittlement susceptibility, impurity elements such as Sn, As, and Sb are each 0.01% or less, preferably 0.005% or less.
本発明鋼の製造条件は特に規定しない。所望する寸法形状、特性に応じて、スラブ加熱温度、熱間圧延条件、熱処理条件を適宜決定し、常法により製造可能である。 The production conditions for the steel of the present invention are not particularly specified. The slab heating temperature, hot rolling conditions, and heat treatment conditions are appropriately determined according to the desired size and shape and characteristics, and can be produced by a conventional method.
表１に示す種々の化学成分を有する鋼を、熱間圧延後、加速冷却して、板厚６０ｍｍの鋼材を製造した。得られた鋼材について常温引張試験（ＪＩＳ Ｚ ２２０１ ４号試験片を用い、ＪＩＳ Ｚ ２２４１に準拠）、シャルピー衝撃試験（ＪＩＳ Ｚ ２２０２ ２ｍｍＶノッチ試験片を用い、ＪＩＳ Ｚ ２２４２に準拠。試験温度ー１０℃、試験法数３本の平均値）およびクリープ破断試験（ＪＩＳ Ｚ ２２７１に準拠）を実施した。 Steels having various chemical components shown in Table 1 were subjected to accelerated cooling after hot rolling to produce steel materials having a thickness of 60 mm. About the obtained steel materials, a normal temperature tensile test (based on JIS Z 2201 No. 4 test piece and conforming to JIS Z 2241), Charpy impact test (using JIS Z 2202 2 mmV notch test piece and conforming to JIS Z 2242. Test temperature -10) C, an average value of three test methods) and a creep rupture test (based on JIS Z 2271) were performed.
また、溶接部のＳＲ割れ特性を調査するため、ＳＲ割れ試験をＪＩＳ Ｚ ３１５８のＹ割れ試験片を用い、斜めＹ割試験片を溶接後にＳＲ（６００℃×４ｈｒ）を実施し、断面割れ率を測定した。尚、クリープ破断試験の試験条件は、Ｌ．Ｍ．Ｐ．＝２００００強度で５２５℃＊１０万時間の試験条件に相当する。 In addition, in order to investigate the SR cracking characteristics of the welded part, SR cracking test was conducted using Y cracking test piece of JIS Z 3158, SR (600 ° C × 4hr) was conducted after welding the oblique Y split specimen, and the cross-sectional cracking rate Was measured. The test conditions for the creep rupture test are as follows. M.M. P. = Corresponds to test conditions of 20,000 ° C. and 525 ° C. * 100,000 hours.
また、低温割れ感受性を調査するため、極低水素系溶接材料を用いて、斜めＹ割れ試験（試験条件３０℃ー８０％、ＪＩＳ Ｚ ３１５８準拠）を実施した。 Moreover, in order to investigate low temperature crack sensitivity, the diagonal Y crack test (Test conditions 30 degreeC-80%, JISZ3158 conformity) was implemented using the ultra-low hydrogen type welding material.
材料強度は、降伏点２１５ＭＰａ以上，引張強度４００〜５１０ＭＰａ、伸び２４％以上を本発明範囲内とし、シャルピー衝撃値は、３本の平均値が１００Ｊ以上を本発明範囲内とし、ＳＲ割れ率、低温割れ率（断面割れ率）はいずれも割れが生じない結果である０％を本発明範囲内とした。クリープ破断試験は、破断強度６０ＭＰａ以上を本発明範囲内とした。 The material strength is a yield point of 215 MPa or more, a tensile strength of 400 to 510 MPa, an elongation of 24% or more is within the scope of the present invention, and the Charpy impact value is within the scope of the present invention with an average value of three being 100 J or more. The low-temperature cracking rate (cross-sectional cracking rate) was set to 0%, which is the result of no cracking, within the scope of the present invention. In the creep rupture test, a rupture strength of 60 MPa or more was set within the range of the present invention.
表１に示す鋼Ｎｏ．１〜３１のうち、鋼Ｎｏ．１，２，３，５，６，９，１０，１３，１４，１７，１８，２１〜２７が本発明鋼、鋼Ｎｏ．４，７，８，１１，１２、１５、１６、１９、２０，２８，２９は成分組成が本発明範囲外の比較鋼で、鋼Ｎｏ．３０はＳＭ４００C、鋼Ｎｏ．３１はＳＢ４８０Ｍの従来例である。表１には低温割れ感受性指数（Ｐｃｍ），ＳＲ割れ感受性指数（ＰＳＲ）をあわせて示す。 Steel No. shown in Table 1 1-31, Steel No. 1, 2, 3, 5, 6, 9, 10, 13, 14, 17, 18, 21 to 27 are steels of the present invention, Steel No. 4, 7, 8, 11, 12, 15, 16, 19, 20, 28, 29 are comparative steels whose component compositions are outside the scope of the present invention. 30 is SM400C, steel no. 31 is a conventional example of SB480M. Table 1 also shows the low temperature cracking sensitivity index (Pcm) and the SR cracking sensitivity index (PSR).
表２に、常温引張試験、シャルピー衝撃試験、クリープ破断試験、ＳＲ割れ試験および斜めＹ割れ試験の結果を示す。本発明鋼は常温強度、クリープ破断強度、シャルピー衝撃値が比較鋼と同等またはそれ以上で、溶接部のＳＲ割れ、低温割れは一切観察されなかった。また、従来鋼より特性の優れていることが確認された。 Table 2 shows the results of a normal temperature tensile test, a Charpy impact test, a creep rupture test, an SR crack test, and an oblique Y crack test. The steel of the present invention has normal temperature strength, creep rupture strength, and Charpy impact value equal to or higher than those of the comparative steel, and no SR cracking and low temperature cracking were observed in the weld. Moreover, it was confirmed that the characteristics are superior to those of conventional steel.
Claims (2)
但し、Ｐｃｍ＝C＋Ｓｉ／３０＋Ｍｎ／２０＋Ｃｕ／２０＋Nｉ／６０＋Ｃｒ／２０＋Ｍｏ／１５＋Ｖ／１０＋５Ｂ
ＰＳＲ＝Ｃｒ＋３．３Ｍｏ＋１０V＋Ｃｕ＋７Nｂ＋５Ｔｉ−２
各式において元素は含有量（質量％）とする。 In mass%, C: 0.03 to 0.15%, Si: 0.01 to 0.50%, Mn: 0.30 to 1.50%, P ≦ 0.015%, S ≦ 0.003% , Mo: 0.2 to 0.6%, Ca: 0.0003 to 0.005%, Mg: 0.0005 to 0.005%, REM: 0.002 to 0.02% Containing sol. Al ≦ 0.04%, N ≦ 0.006 %, O ≦ 0.003%, Pcm ≦ 0.22%, P SR <0, the converter steel skins steel material and the balance Fe and unavoidable impurities.
However, Pcm = C + Si / 30 + Mn / 20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B
P SR = Cr + 3.3Mo + 10V + Cu + 7Nb + 5Ti-2
In each formula, the element is the content (% by mass).
但し、Ｐｃｍ＝C＋Ｓｉ／３０＋Ｍｎ／２０＋Ｃｕ／２０＋Nｉ／６０＋Ｃｒ／２０＋Ｍｏ／１５＋Ｖ／１０＋５Ｂ
ＰＳＲ＝Ｃｒ＋３．３Ｍｏ＋１０V＋Ｃｕ＋７Nｂ＋５Ｔｉ−２
各式において元素は含有量（質量％）とする。 In addition to the component composition of claim 1, Cu: 0.03-0.5%, Ni: 0.03-0.5%, Cr: 0.03-0.7%, V: 0.005-0 0.05%, Ti: 0.005 to 0.05%, Nb: 0.005 to 0.03%, B: 0.0003 to 0.002%, or one or more types A steel material for a converter core comprising Pcm ≦ 0.22%, P SR <0, the balance Fe and inevitable impurities.
However, Pcm = C + Si / 30 + Mn / 20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B
P SR = Cr + 3.3Mo + 10V + Cu + 7Nb + 5Ti-2
In each formula, the element is the content (% by mass).
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| CN103290339A (en) * | 2013-06-29 | 2013-09-11 | 首钢总公司 | High-strength steel plate for 800MPa hydropower station pressure pipeline and production method thereof |
| JP2022097391A (en) * | 2020-12-18 | 2022-06-30 | Ｊｆｅスチール株式会社 | Steel material for iron shell of melt container, iron shell of container for receiving melt, and container for receiving melt |
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| CN103290339A (en) * | 2013-06-29 | 2013-09-11 | 首钢总公司 | High-strength steel plate for 800MPa hydropower station pressure pipeline and production method thereof |
| JP2022097391A (en) * | 2020-12-18 | 2022-06-30 | Ｊｆｅスチール株式会社 | Steel material for iron shell of melt container, iron shell of container for receiving melt, and container for receiving melt |
| JP7334771B2 (en) | 2020-12-18 | 2023-08-29 | Ｊｆｅスチール株式会社 | Steel for the shell of the container for the melt, the shell of the container for containing the melt, and the container for containing the melt |
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