TWI630277B - High manganese steel plate and manufacturing method thereof - Google Patents
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- 229910000617 Mangalloy Inorganic materials 0.000 title claims abstract description 23
- 238000004519 manufacturing process Methods 0.000 title claims description 18
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 110
- 239000010959 steel Substances 0.000 claims abstract description 110
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 45
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 42
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 42
- 239000000203 mixture Substances 0.000 claims abstract description 18
- 239000011572 manganese Substances 0.000 claims abstract description 12
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 7
- 239000012535 impurity Substances 0.000 claims abstract description 6
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 6
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 5
- 239000011159 matrix material Substances 0.000 claims abstract description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 3
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 3
- 239000000463 material Substances 0.000 claims description 44
- 238000005096 rolling process Methods 0.000 claims description 31
- 238000001816 cooling Methods 0.000 claims description 26
- 150000004767 nitrides Chemical class 0.000 claims description 13
- 150000001247 metal acetylides Chemical class 0.000 claims description 11
- 229910052799 carbon Inorganic materials 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 10
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 9
- 150000002910 rare earth metals Chemical class 0.000 claims description 9
- 238000005098 hot rolling Methods 0.000 claims description 7
- 229910052721 tungsten Inorganic materials 0.000 claims description 3
- 229910052750 molybdenum Inorganic materials 0.000 claims description 2
- 238000000034 method Methods 0.000 abstract description 11
- 230000007797 corrosion Effects 0.000 description 56
- 238000005260 corrosion Methods 0.000 description 56
- 238000005336 cracking Methods 0.000 description 43
- 230000000694 effects Effects 0.000 description 36
- 229910052739 hydrogen Inorganic materials 0.000 description 25
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 24
- 239000001257 hydrogen Substances 0.000 description 24
- 239000002244 precipitate Substances 0.000 description 17
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 8
- 238000003860 storage Methods 0.000 description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 5
- 230000006835 compression Effects 0.000 description 5
- 238000007906 compression Methods 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 229920006395 saturated elastomer Polymers 0.000 description 5
- 238000009864 tensile test Methods 0.000 description 5
- 239000013078 crystal Substances 0.000 description 4
- 230000001186 cumulative effect Effects 0.000 description 4
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- 239000007789 gas Substances 0.000 description 4
- 238000010191 image analysis Methods 0.000 description 4
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 4
- 230000035515 penetration Effects 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- 239000006104 solid solution Substances 0.000 description 4
- 230000006641 stabilisation Effects 0.000 description 4
- 238000011105 stabilization Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 238000005266 casting Methods 0.000 description 3
- 239000002131 composite material Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000007670 refining Methods 0.000 description 3
- 238000010998 test method Methods 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000009749 continuous casting Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 239000008187 granular material Substances 0.000 description 2
- 238000009863 impact test Methods 0.000 description 2
- 238000011835 investigation Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 239000003949 liquefied natural gas Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 230000008520 organization Effects 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000013535 sea water Substances 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000012267 brine Substances 0.000 description 1
- 239000003518 caustics Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000001814 effect on stress Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000000877 morphologic effect Effects 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- HRZFUMHJMZEROT-UHFFFAOYSA-L sodium disulfite Chemical compound [Na+].[Na+].[O-]S(=O)S([O-])(=O)=O HRZFUMHJMZEROT-UHFFFAOYSA-L 0.000 description 1
- 229940001584 sodium metabisulfite Drugs 0.000 description 1
- 235000010262 sodium metabisulphite Nutrition 0.000 description 1
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 238000009849 vacuum degassing Methods 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
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- Heat Treatment Of Steel (AREA)
Abstract
本發明提供一種高錳鋼板及其製造方法。一種高錳鋼板,其具有以質量%計而言含有C:0.20%~0.70%、Si:0.05%~1.0%、Mn:15%~30%、P:0.028%以下、S:0.02%以下、Al:0.01%~0.1%、Cr:0.5%~7.0%、Ni:0.03%~0.30%、N:0.0010%~0.0200%,且含有Nb:0.003%~0.030%、V:0.03%~0.10%、Ti:0.003%~0.040%的一種或兩種以上,剩餘部分包含Fe及不可避免的雜質的成分組成,鋼板表面下0.5 mm的微組織以沃斯田體為基質相,該沃斯田體中的面積率的25%以上是圓等效直徑為10 μm以上,且長徑與短徑的縱橫比為3以上。The present invention provides a high manganese steel sheet and a method of producing the same. A high manganese steel sheet containing C: 0.20% to 0.70%, Si: 0.05% to 1.0%, Mn: 15% to 30%, P: 0.028% or less, and S: 0.02% or less, by mass%; Al: 0.01% to 0.1%, Cr: 0.5% to 7.0%, Ni: 0.03% to 0.30%, N: 0.0010% to 0.0200%, and Nb: 0.003% to 0.030%, V: 0.03% to 0.10%, Ti: 0.003% to 0.040% of one or two or more, and the remainder contains a composition of Fe and unavoidable impurities. The microstructure of 0.5 mm under the surface of the steel sheet is a matrix phase of the Worth field, which is in the Worth field. 25% or more of the area ratio is a circle equivalent diameter of 10 μm or more, and an aspect ratio of the long diameter to the short diameter is 3 or more.
Description
本發明是有關於一種適合供至液化氣儲存槽用儲罐等在極低溫環境下使用的結構用鋼的特別是在鹽水腐蝕環境下的耐應力腐蝕破裂性優異的高錳鋼板及其製造方法。 The present invention relates to a high-manganese steel sheet excellent in stress corrosion cracking resistance, particularly in a brine corrosion environment, which is suitable for use in a storage tank for a liquefied gas storage tank or the like in a very low temperature environment, and a method for producing the same .
在液化氣儲存槽用結構物中使用熱軋鋼板時,使用環境變為極低溫,因此不僅要求鋼板的強度,亦要求在極低溫下的韌性。例如,在液化天然氣的儲存槽中使用熱軋鋼板的情況下,必需在液化天然氣的沸點(-164℃)以下確保優異的韌性。如果鋼材的低溫韌性差,則存在變得無法維持作為極低溫儲存槽用結構物的安全性的危險性,因此對於使所應用的鋼材的低溫韌性提高的要求強烈。對於該要求,於先前使用並不在極低溫下顯示出脆性的以沃斯田體為鋼板組織的沃斯田體系不鏽鋼或9%鎳(Ni)鋼、或者5000系鋁合金。然而,由於合金成本或製造成本高,因此存在對於廉價且極低溫韌性優異的鋼材的迫切期望。因此,作為代替先前的極低溫用鋼的新型鋼材,研究使用大量添加有相對廉價的沃斯田體穩定化元素錳(Mn)的高錳鋼板作為極低溫環境的結構用鋼。 When a hot-rolled steel sheet is used for the structure for a liquefied gas storage tank, the use environment becomes extremely low temperature, and therefore the strength of the steel sheet is required, and the toughness at an extremely low temperature is also required. For example, in the case of using a hot-rolled steel sheet in a storage tank of a liquefied natural gas, it is necessary to ensure excellent toughness at a boiling point (-164 ° C) or lower of the liquefied natural gas. If the low-temperature toughness of the steel material is inferior, there is a risk that the safety of the structure for the cryogenic storage tank cannot be maintained. Therefore, there is a strong demand for improving the low-temperature toughness of the applied steel material. For this requirement, a Woustian system stainless steel or a 9% nickel (Ni) steel or a 5000 series aluminum alloy in which a Worth field is a steel sheet structure which does not exhibit brittleness at an extremely low temperature has been used. However, since the alloy cost or the manufacturing cost is high, there is an urgent need for a steel material which is excellent in inexpensive and extremely low temperature toughness. Therefore, as a new type of steel material in place of the conventional ultra-low temperature steel, a large amount of high-manganese steel sheet to which a relatively inexpensive Worstian body stabilized element manganese (Mn) is added is used as a structural steel for an extremely low temperature environment.
另一方面,於在腐蝕環境下使用沃斯田體鋼的情況下,存在如下問題:沃斯田體晶粒邊界由於腐蝕而受到侵蝕,在附加 拉應力的情況下,容易產生應力腐蝕破裂。特別是在液化氣儲存槽用結構物等的製作階段,存在鋼板的肥粒鐵(ferrite)表面露出的情況,鋼材表面若與包含鹽分等腐蝕性物質的水蒸氣、或者水分或油分等接觸,則產生鋼材的腐蝕。若為自先前便研究的高錳鋼板,則存在如下的情況:與9%鎳鋼或通常的低合金鋼相比較而言,沃斯田體系不鏽鋼當然耐蝕性差。此時,在高錳鋼板表面的腐蝕反應中,鐵由於陽極反應而生成氧化物(鏽),另一方面由於水分的陰極反應而產生氫,由於氫脆化而助長應力腐蝕破裂。存在如下的危險性:如上所述而產生的應力腐蝕破裂在製作時的彎曲加工或焊接等的殘留應力、或者使用環境下的負載應力的存在下,以至於破壞結構物。因此,自安全性的觀點考慮,重要的是所使用的鋼材當然強度與極低溫韌性優異,耐應力腐蝕破裂性亦優異。 On the other hand, in the case of using Worthfield steel in a corrosive environment, there is a problem that the grain boundary of the Worth field is eroded by corrosion, and is attached. In the case of tensile stress, stress corrosion cracking easily occurs. In particular, in the production stage of the structure for a liquefied gas storage tank, the surface of the ferrite of the steel sheet may be exposed, and if the surface of the steel material is in contact with water vapor or moisture or oil containing a corrosive substance such as salt, It causes corrosion of the steel. In the case of a high-manganese steel sheet which has been studied from the past, there is a case where the Vostian system stainless steel is of poor corrosion resistance as compared with 9% nickel steel or a usual low-alloy steel. At this time, in the corrosion reaction on the surface of the high-manganese steel sheet, iron generates an oxide (rust) due to the anode reaction, and hydrogen is generated by the cathode reaction of moisture, which promotes stress corrosion cracking due to hydrogen embrittlement. There is a risk that the stress corrosion cracking as described above may be caused by the residual stress such as bending work or welding at the time of production or the load stress in the use environment, so that the structure is broken. Therefore, from the viewpoint of safety, it is important that the steel material used is excellent in strength and extremely low temperature toughness, and is excellent in stress corrosion cracking resistance.
例如,在專利文獻1中揭示一種鋼材,其添加有Mn:15%~35%、Cu:5%以下,進而適量添加有C與Cr,藉此改善切削性及熔接熱影響部在-196℃下的夏比衝擊(Charpy impact)特性。 For example, Patent Document 1 discloses a steel material in which Mn: 15% to 35% and Cu: 5% or less are added, and C and Cr are added in an appropriate amount to improve machinability and weld heat influence at -196 ° C. The Charpy impact feature.
而且,在專利文獻2中揭示一種高錳鋼材,其添加有C:0.25%~0.75%、Si:0.05%~1.0%、Mn:超過20%且35%以下、Ni:0.1%以上且不足7.0%、Cr:0.1%以上且不足8.0%,改善了低溫韌性。 Further, Patent Document 2 discloses a high manganese steel material in which C: 0.25% to 0.75%, Si: 0.05% to 1.0%, Mn: more than 20% and 35% or less, and Ni: 0.1% or more and less than 7.0 are added. %, Cr: 0.1% or more and less than 8.0%, and improved low temperature toughness.
[現有技術文獻] [Prior Art Literature]
[專利文獻] [Patent Literature]
專利文獻1:日本專利特表2015-508452號公報 Patent Document 1: Japanese Patent Laid-Open Publication No. 2015-508452
專利文獻2:日本專利特開2016-84529號公報 Patent Document 2: Japanese Patent Laid-Open No. 2016-84529
然而,專利文獻1、專利文獻2中所記載的高錳鋼板以具有強度與低溫韌性為目的,熔接熱影響部在-196℃下的夏比衝擊特性為60J~135J(僅顯示於專利文獻1中)。但是,母材的極低溫韌性尚不充分,並未兼顧極低溫韌性與耐應力腐蝕破裂性。 However, the high manganese steel sheets described in Patent Document 1 and Patent Document 2 have a Charpy impact characteristic at 60 ° C to 135 J at -196 ° C for the purpose of having strength and low temperature toughness (only shown in Patent Document 1). in). However, the extremely low temperature toughness of the base material is not sufficient, and the low temperature toughness and the stress corrosion cracking resistance are not considered.
本發明是鑒於該問題,其目的在於提供一種極低溫韌性、耐應力腐蝕破裂性優異的高錳鋼板及其製造方法。 The present invention has been made in view of the above problems, and an object thereof is to provide a high manganese steel sheet excellent in extremely low temperature toughness and stress corrosion cracking resistance and a method for producing the same.
本發明者等人為了達成所述課題,以高錳鋼板為對象,關於用以確保優異的耐應力腐蝕破裂性能的鋼板的成分組成、製造方法及決定微組織的各種因素進行了銳意研究,獲得以下的發現。 In order to achieve the above-mentioned problems, the present inventors have made intensive studies on the composition, manufacturing method, and various factors for determining the microstructure of a steel sheet for ensuring excellent stress corrosion cracking resistance for a high-manganese steel sheet. The following findings.
1.為了兼顧極低溫韌性與優異的耐應力腐蝕破裂性,有效的是使經由腐蝕反應的於鋼板中的氫滲入量降低的方法。重要的是在鹽水腐蝕環境下,使鋼板表面的耐蝕性提高,因此重要的是以高錳鋼板為基礎而嚴格地管理成分組成。特別是同時添加Cr與Ni,適當地控制其添加量,藉此使鋼板表面的腐蝕反應的初期所形成的鏽變得微細。而且,可藉由使其後的腐蝕反應延遲而減低鋼中所滲入的氫量。 1. In order to achieve both low-temperature toughness and excellent stress corrosion cracking resistance, it is effective to reduce the amount of hydrogen permeation in the steel sheet by a corrosion reaction. It is important to improve the corrosion resistance of the steel sheet surface in a salt water corrosive environment, so it is important to strictly manage the composition of the composition based on the high manganese steel sheet. In particular, Cr and Ni are simultaneously added, and the amount of addition is appropriately controlled, whereby the rust formed at the initial stage of the corrosion reaction on the surface of the steel sheet is fine. Moreover, the amount of hydrogen permeated in the steel can be reduced by delaying the subsequent corrosion reaction.
2.進而發現嚴格地管理鋼板表面附近的微組織的方法亦於改善耐應力腐蝕破裂性的方面有效。亦即,沃斯田體中的面積率為25%以上是圓等效直徑為10μm以上、且長徑與短徑的縱橫比為3以上於使應力腐蝕破裂性提高的方面而言變重要。認為其原因在於:由於腐蝕反應而滲入至鋼板內部的氫被捕獲於未再結晶沃斯田體的結晶粒內,因此沃斯田體晶界上的氫量相對性降低,沃斯田體晶界的應力腐蝕破裂感受性降低。 2. Further, it has been found that a method of strictly managing the microstructure near the surface of the steel sheet is also effective in improving the stress corrosion cracking resistance. In other words, the area ratio of the Worth field is 25% or more, and the circle equivalent diameter is 10 μm or more, and the aspect ratio of the long diameter to the short diameter is 3 or more, which is important in terms of improving stress corrosion cracking. It is considered that the reason is that hydrogen which has penetrated into the inside of the steel sheet due to the corrosion reaction is trapped in the crystal grains of the non-recrystallized Worth field body, so the relative amount of hydrogen on the grain boundary of the Worthfield body is lowered, and the stress corrosion of the grain boundary of the Worthfield body is suppressed. The rupture sensitivity is reduced.
3.除所述1、2以外,鋼板中的Nb、V、Ti的碳化物、氮化物及複合碳氮化物可藉由適當地管理其分散狀態而使耐應力腐蝕破裂性進而提高。Nb、V、Ti的碳化物、氮化物及複合碳氮化物於鋼板中作為擴散性氫的捕獲部位起作用。亦即,作為由於鋼材的腐蝕反應而生成的擴散性氫的捕獲部位起作用,具有抑制應力腐蝕破裂的效果。熱軋步驟的加熱、軋製、及冷卻條件等對沃斯田體中的Nb、V、Ti的碳化物、氮化物及複合碳氮化物的分散狀態造成影響。因此,重要的是管理該些製造條件。 3. In addition to the above 1, 2, carbides, nitrides, and composite carbonitrides of Nb, V, and Ti in the steel sheet can be further improved in stress corrosion cracking resistance by appropriately managing the dispersion state thereof. Carbides, nitrides, and composite carbonitrides of Nb, V, and Ti act as a trapping portion of diffusible hydrogen in the steel sheet. In other words, it acts as a trapping portion of diffusible hydrogen generated by the corrosion reaction of the steel material, and has an effect of suppressing stress corrosion cracking. The heating, rolling, and cooling conditions in the hot rolling step affect the dispersion state of carbides, nitrides, and composite carbonitrides of Nb, V, and Ti in the Worth field. Therefore, it is important to manage these manufacturing conditions.
4.進而,為了有效地抑制沃斯田體晶界破壞,有效的是提高晶粒邊界強度的對策。P是在鋼片的凝固過程中,容易與Mn一同共偏析的元素,使與微偏析部相交的晶粒邊界強度降低。因此,必需使P等雜質元素減低。 4. Further, in order to effectively suppress the grain boundary destruction of the Worthfield, it is effective to improve the grain boundary strength. P is an element which is easily segregated together with Mn during solidification of the steel sheet, and the grain boundary strength which intersects with the microsegregation portion is lowered. Therefore, it is necessary to reduce the impurity element such as P.
本發明是對以上發現進而加以研究而成者,其主旨如下所示。 The present invention has been made in view of the above findings, and its gist is as follows.
[1]一種高錳鋼板,其具有以質量%計而言含有C:0.20%~ 0.70%、Si:0.05%~1.0%、Mn:15%~30%、P:0.028%以下、S:0.02%以下、Al:0.01%~0.1%、Cr:0.5%~7.0%、Ni:0.03%~0.30%、N:0.0010%~0.0200%,且含有Nb:0.003%~0.030%、V:0.03%~0.10%、Ti:0.003%~0.040%的一種或兩種以上,剩餘部分包含Fe及不可避免的雜質的成分組成,鋼板表面下0.5mm的微組織以沃斯田體為基質相,該沃斯田體中的面積率的25%以上是圓等效直徑為10μm以上,且長徑與短徑的縱橫比為3以上。 [1] A high manganese steel sheet having C: 0.20% by mass% 0.70%, Si: 0.05% to 1.0%, Mn: 15% to 30%, P: 0.028% or less, S: 0.02% or less, Al: 0.01% to 0.1%, Cr: 0.5% to 7.0%, Ni: 0.03 %~0.30%, N: 0.0010%~0.0200%, and one or more of Nb: 0.003%~0.030%, V: 0.03%~0.10%, Ti: 0.003%~0.040%, and the remainder contains Fe and The composition of the unavoidable impurities, the microstructure of 0.5 mm under the surface of the steel sheet is the matrix phase of the Worth field, and the area ratio of 25% or more in the Worth field is a circle equivalent diameter of 10 μm or more, and the long diameter The aspect ratio to the short diameter is 3 or more.
[2]如[1]所述的高錳鋼板,其中,除了所述成分組成以外,進而含有選自下述群組A或群組B中的至少一個群組的元素;群組A:以質量%計而言,選自Mo:0.05%~2.0%、W:0.05%~2.0%中的一種或兩種;群組B:以質量%計而言,選自Ca:0.0005%~0.0050%、Mg:0.0005%~0.0050%、稀土金屬(REM):0.0010%~0.0200%中的一種或兩種以上。 [2] The high manganese steel sheet according to [1], wherein, in addition to the component composition, further comprising an element selected from at least one of Group A or Group B described below; Group A: In terms of mass%, one or two selected from the group consisting of Mo: 0.05% to 2.0%, W: 0.05% to 2.0%; Group B: in terms of mass%, selected from Ca: 0.0005% to 0.0050% , Mg: 0.0005% to 0.0050%, rare earth metal (REM): one or more of 0.0010% to 0.0200%.
[3]如[1]或[2]所述的高錳鋼板,其中,關於鋼板表面下0.5mm的所述微組織,進而於所述微組織中具有合計2×102個/mm2以上的圓等效直徑為0.01μm~0.5μm的含有Nb、V、Ti的一種或兩種以上的碳化物、氮化物及碳氮化物。 [3] The high-manganese steel sheet according to [1] or [2], wherein the microstructure of 0.5 mm below the surface of the steel sheet further has a total of 2 × 10 2 /mm 2 or more in the microstructure. The round equivalent diameter is from 0.01 μm to 0.5 μm, and one or two or more kinds of carbides, nitrides, and carbonitrides containing Nb, V, and Ti.
[4]一種高錳鋼板的製造方法,其是將具有[1]~[3]中任一項所述的成分組成的鋼原材料加熱至如下之溫度區域,亦即於將Tx(x=Nb、V或Ti)設為式(1)~式(3)所示的溫度時,以式(1)~式(3)所定義的Tx(℃)的任意一個以上表示而言,鋼原材 料的表面溫度為(Tx-50)℃以上、(Tx+200)℃以下的溫度區域,進行精軋結束溫度為750℃以上、1000℃以下的熱軋而製造鋼板,其後,以自(精軋結束溫度-50℃)或冷卻開始溫度的任意較低的溫度至650℃的鋼板表面的平均冷卻速度為1.0℃/s以上進行冷卻;TNb(℃)=7500/{3.0-log10([%Nb]×[%C])}-273…(1) [4] A method for producing a high-manganese steel sheet, wherein the steel material having the chemical composition according to any one of [1] to [3] is heated to a temperature region, that is, Tx (x = Nb) When V, Ti or Ti) is at a temperature represented by the formula (1) to the formula (3), the steel material is represented by any one or more of Tx (°C) defined by the formulas (1) to (3). The surface temperature is (Tx-50) ° C or more and (Tx + 200) ° C or less, and the finish rolling temperature is 750 ° C or more and 1000 ° C or less, and the steel sheet is produced, and thereafter, the steel sheet is self-rolled. Cooling at any lower temperature of the end temperature of -50 ° C) or the cooling start temperature to the surface of the steel sheet of 650 ° C is 1.0 ° C / s or more for cooling; T Nb ( ° C ) = 7500 / {3.0 - log 10 ([ %Nb]×[%C])}-273...(1)
Tv(℃)=10800/{7.2-log10([%V]×[%C])}-273…(2) Tv(°C)=10800/{7.2-log 10 ([%V]×[%C])}-273...(2)
TTi(℃)=7000/{2.8-log10([%Ti]×[%C])}-273…(3) T Ti (°C)=7000/{2.8-log 10 ([%Ti]×[%C])}-273...(3)
此處,[%Nb]、[%V]、[%Ti]及[%C]分別表示鋼中的Nb、V、Ti及C的含量(質量%);在並未含有的元素的情況下,將式中的元素記號設為0而進行計算。 Here, [%Nb], [%V], [%Ti], and [%C] respectively represent the content (% by mass) of Nb, V, Ti, and C in the steel; in the case of an element not contained Calculate by setting the element symbol in the formula to 0.
再者,於本發明中,所謂「高強度」是指具有降伏強度為400MPa以上的強度者。而且,於本發明中,所謂「極低溫韌性」是指低溫韌性、亦即-196℃下的夏比衝擊試驗的吸收能量vE-196為50J以上。進而,於本發明中,所謂「耐應力腐蝕破裂性優異」是指在進行依據美國國際腐蝕工程師協會(National Association of Corrosion Engineers,NACE)標準TM0111-2011基準的慢應變速率試驗方法(Slow Strain Rate Test Method)的試驗,亦即在溫度為23℃下浸漬於人工海水(氯化物離子濃度為18000ppm)中,以4×10-7inch/sec.的應變速度進行等速拉伸試驗的情況下,破斷應力為500MPa以上。 In the present invention, the term "high strength" means a strength having a strength of 400 MPa or more. Further, in the present invention, the "very low temperature toughness" means that the low temperature toughness, that is, the absorbed energy vE- 196 of the Charpy impact test at -196 ° C is 50 J or more. Further, in the present invention, "excellent stress corrosion cracking resistance" means a slow strain rate test method (Slow Strain Rate) according to the National Association of Corrosion Engineers (NACE) standard TM0111-2011. Test Method), that is, immersed in artificial seawater (chloride ion concentration: 18000 ppm) at a temperature of 23 ° C, and subjected to a constant-speed tensile test at a strain rate of 4 × 10 -7 inches / sec. The breaking stress is 500 MPa or more.
藉由本發明可獲得耐應力腐蝕破裂性優異的高錳鋼板。而且,本發明的高錳鋼板較大地有助於使液化氣儲存槽用儲罐等在極低溫環境下使用的鋼結構物的安全性或壽命提高,於產業上格外有效。而且,並不引起生產性降低及製造成本增大,因此經濟性優異。 According to the present invention, a high manganese steel sheet excellent in stress corrosion cracking resistance can be obtained. Further, the high manganese steel sheet of the present invention contributes greatly to the safety and life of the steel structure used in a cryogenic environment such as a storage tank for a liquefied gas storage tank, and is industrially effective. Moreover, it does not cause a decrease in productivity and an increase in manufacturing cost, and therefore is excellent in economy.
以下,對本發明的實施方式加以說明。再者,本發明並不限定於以下的實施方式。 Hereinafter, embodiments of the present invention will be described. Furthermore, the present invention is not limited to the following embodiments.
[成分組成] [component composition]
首先,關於本發明的鋼板的成分組成與其限定理由加以說明。在本發明中,為了確保優異的耐應力腐蝕破裂性,如下所述地規定鋼板的成分組成。再者,表示成分組成的%若無特別說明則表示質量%。 First, the component composition of the steel sheet of the present invention will be described with respect to the reason for limitation. In the present invention, in order to secure excellent stress corrosion cracking resistance, the chemical composition of the steel sheet is defined as follows. In addition, the % which shows the component composition shows the mass % unless it demonstrates especially.
C:0.20%~0.70% C: 0.20%~0.70%
C是廉價的沃斯田體穩定化元素,其是用以獲得沃斯田體的重要元素。為了獲得其效果,C必須含有0.20%以上。另一方面,若含有超過0.70%,則過度地生成Cr碳化物及Nb、V、Ti系碳化物,低溫韌性及耐應力腐蝕破裂性降低。因此,C為0.20%~ 0.70%。較佳為0.25%以上。較佳為0.60%以下。 C is an inexpensive Worth field stabilization element that is used to obtain important elements of the Worth field. In order to obtain the effect, C must contain 0.20% or more. On the other hand, when it contains more than 0.70%, Cr carbide and Nb, V, and Ti-based carbide are excessively formed, and low-temperature toughness and stress corrosion cracking resistance are lowered. Therefore, C is 0.20%~ 0.70%. It is preferably 0.25% or more. It is preferably 0.60% or less.
Si:0.05%~1.0% Si: 0.05%~1.0%
Si作為脫氧材料而起作用,不僅在製鋼上必需,而且具有固溶於鋼中藉由固溶強化而使鋼板高強度化的效果。為了獲得此種效果,Si必須含有0.05%以上。另一方面,若含有超過1.0%,則焊接性劣化。而且,亦對耐應力腐蝕破裂(Stress Corrosion Cracking,SCC)性有影響。因此,Si為0.05%~1.0%。較佳為0.07%以上。較佳為0.5%以下。 Si acts as a deoxidizing material, and is not only required for steel making, but also has an effect of solid-solution strengthening in steel to strengthen the steel sheet by solid solution strengthening. In order to obtain such an effect, Si must contain 0.05% or more. On the other hand, when it contains more than 1.0%, weldability will deteriorate. Moreover, it also has an effect on Stress Corrosion Cracking (SCC). Therefore, Si is 0.05% to 1.0%. It is preferably 0.07% or more. It is preferably 0.5% or less.
Mn:15%~30% Mn: 15% to 30%
Mn是相對廉價的沃斯田體穩定化元素。在本發明中是用以兼顧強度與極低溫韌性的重要元素。為了獲得該效果,Mn必須含有15%以上。另一方面,即使含有超過30%,亦由於改善極低溫韌性的效果飽和,導致合金成本上升。而且,焊接性、切斷性劣化。進而,助長偏析,助長耐應力腐蝕破裂的產生。因此,Mn為15%~30%。較佳為18%以上。較佳為28%以下。 Mn is a relatively inexpensive Worth field stabilization element. In the present invention, it is an important element for achieving both strength and extremely low temperature toughness. In order to obtain this effect, Mn must contain 15% or more. On the other hand, even if it contains more than 30%, the effect of improving the low-temperature toughness is saturated, resulting in an increase in alloy cost. Further, the weldability and the cutting property are deteriorated. Further, it promotes segregation and promotes the generation of stress corrosion cracking. Therefore, Mn is 15% to 30%. It is preferably 18% or more. It is preferably 28% or less.
P:0.028%以下 P: 0.028% or less
P若含有超過0.028%,則偏析於晶界,成為耐應力腐蝕破裂的產生起點。因此,理想的是以0.028%為上限,儘可能地減低。因此,P為0.028%以下。再者,過度的P減低使精煉成本暴增而於經濟上變得不利,因此理想的是0.002%以上。較佳為0.005%以上。較佳為0.024%以下。 When P contains more than 0.028%, it segregates to the grain boundary and becomes a starting point for stress corrosion cracking. Therefore, it is desirable to use 0.028% as the upper limit and reduce as much as possible. Therefore, P is 0.028% or less. Furthermore, excessive P reduction causes a sharp increase in refining costs and is economically disadvantageous, so it is desirable to be 0.002% or more. It is preferably 0.005% or more. It is preferably 0.024% or less.
S:0.02%以下 S: 0.02% or less
S使母材的低溫韌性或延性劣化,因此理想的是以0.02%為上限,儘可能地減低。因此,S為0.02%以下。再者,過度的S減低使精煉成本暴增而於經濟上變得不利,因此理想的是0.001%以上。較佳為0.002%以上。較佳為0.018%以下。 Since S deteriorates the low temperature toughness or ductility of the base material, it is desirable to reduce the temperature as much as possible by 0.02%. Therefore, S is 0.02% or less. Furthermore, excessive S reduction causes a sharp increase in refining costs and is economically disadvantageous, so it is desirable to be 0.001% or more. It is preferably 0.002% or more. It is preferably 0.018% or less.
Al:0.01%~0.1% Al: 0.01%~0.1%
Al作為脫氧劑而起作用,於鋼板的溶鋼脫氧製程中最通用地使用。而且,具有將鋼中的固溶N固定而形成AlN,從而抑制結晶粒的粗大化的效果。並且具有抑制由於固溶N減低所造成的韌性劣化的效果。為了獲得此種效果,Al必須含有0.01%以上。另一方面,若含有超過0.1%,則於焊接時混入至焊接金屬部,使焊接金屬的韌性劣化,因此為0.1%以下。因此,Al為0.01%~0.1%。較佳為0.02%以上。較佳為0.07%以下。 Al acts as a deoxidizer and is most commonly used in the steel strip deoxidation process of steel sheets. Further, it has an effect of fixing solid solution N in the steel to form AlN, thereby suppressing coarsening of crystal grains. Further, it has an effect of suppressing deterioration of toughness due to reduction in solid solution N. In order to obtain such an effect, Al must contain 0.01% or more. On the other hand, when the content exceeds 0.1%, the weld metal portion is mixed during welding, and the toughness of the weld metal is deteriorated, so that it is 0.1% or less. Therefore, Al is 0.01% to 0.1%. It is preferably 0.02% or more. It is preferably 0.07% or less.
Cr:0.5%~7.0% Cr: 0.5%~7.0%
Cr是藉由適量添加而使沃斯田體穩定化,對於提高極低溫韌性與母材強度而言有效的元素。而且,在本發明中,其是經由使在鹽水環境下的母材表面生成的鏽緻密的效果,使氫於鋼板中的滲入量降低,使耐應力腐蝕破裂性提高的重要元素。為了獲得此種效果,Cr必須含有0.5%以上。另一方面,若含有超過7.0%,則由於Cr碳化物的生成而造成低溫韌性及耐應力腐蝕破裂性降低。因此,Cr為0.5%~7.0%。較佳為1.0%以上、更佳為1.2%以上、進而較佳為2.5%。較佳為6.0%以下、更佳為5.7%、進而較佳為5.5%以下。 Cr is an element which is stabilized by a proper amount to stabilize the Worth field and is effective for improving the low temperature toughness and the strength of the base material. Further, in the present invention, it is an important element for improving the penetration resistance of hydrogen in the steel sheet by reducing the amount of penetration of hydrogen into the steel sheet by the effect of densifying the rust generated on the surface of the base material in a salt water environment. In order to obtain such an effect, Cr must contain 0.5% or more. On the other hand, when it contains more than 7.0%, low temperature toughness and stress corrosion cracking resistance fall by the formation of Cr carbide. Therefore, Cr is 0.5% to 7.0%. It is preferably 1.0% or more, more preferably 1.2% or more, and still more preferably 2.5%. It is preferably 6.0% or less, more preferably 5.7%, still more preferably 5.5% or less.
Ni:0.03%~0.30% Ni: 0.03%~0.30%
Ni是代表性的沃斯田體穩定化元素,其是對於提高極低溫韌性與母材強度而言有效的元素。而且,在本發明中,其是經由使在鹽水環境下的母材表面生成的鏽緻密的效果,使氫於鋼板中的滲入量降低,使耐應力腐蝕破裂性提高的重要元素。為了獲得此種效果,Ni必須含有0.03%以上。另一方面,若含有超過0.30%,則合金成本上升,且耐應力腐蝕破裂性的提高效果飽和。因此,Ni為0.03%~0.30%。較佳為0.04%以上。較佳為0.25%以下。 Ni is a representative Worth field stabilization element which is an element effective for improving the extremely low temperature toughness and the strength of the base material. Further, in the present invention, it is an important element for improving the penetration resistance of hydrogen in the steel sheet by reducing the amount of penetration of hydrogen into the steel sheet by the effect of densifying the rust generated on the surface of the base material in a salt water environment. In order to obtain such an effect, Ni must contain 0.03% or more. On the other hand, when the content exceeds 0.30%, the alloy cost increases, and the effect of improving the stress corrosion cracking resistance is saturated. Therefore, Ni is 0.03% to 0.30%. It is preferably 0.04% or more. It is preferably 0.25% or less.
N:0.0010%~0.0200% N: 0.0010%~0.0200%
N是沃斯田體穩定化元素,其是對於提高極低溫韌性而言有效的元素。而且,具有與Nb、V、Ti鍵結而作為氮化物或碳氮化物析出,作為擴散性氫的捕獲部位而抑制應力腐蝕破裂的效果。為了獲得此種效果,N必須含有0.0010%以上。另一方面,若含有超過0.0200%,則氮化物或碳氮化物粗大化,韌性降低。因此,N為0.0010%~0.0200%。較佳為0.0020%以上。較佳為0.0150%以下。 N is a Worth field stabilization element which is an element effective for improving the extremely low temperature toughness. Further, it has an effect of binding to Nb, V, and Ti to precipitate as a nitride or a carbonitride, and suppressing stress corrosion cracking as a trapping portion of diffusible hydrogen. In order to obtain such an effect, N must contain 0.0010% or more. On the other hand, when the content exceeds 0.0200%, the nitride or carbonitride is coarsened and the toughness is lowered. Therefore, N is 0.0010% to 0.0200%. It is preferably 0.0020% or more. It is preferably 0.0150% or less.
Nb:0.003%~0.030%、V:0.03%~0.10%、Ti:0.003%~0.040%的一種或兩種以上 Nb: 0.003% to 0.030%, V: 0.03% to 0.10%, Ti: 0.003% to 0.040%, one or more
Nb:0.003%~0.030% Nb: 0.003%~0.030%
Nb是作為碳氮化物(包括碳化物)而析出,所生成的碳氮化物於擴散性氫的捕獲部位有效,具有抑制應力腐蝕破裂的效果的元素。為了獲得此種效果,Nb必須含有0.003%以上。另一方面, 若含有超過0.030%,則存在析出粗大的碳氮化物,成為破壞的起點的現象。而且,存在析出物粗大化,使母材韌性劣化的現象。因此,在含有Nb的情況下為0.003%~0.030%。較佳為0.005%以上、更佳為0.007%以上。較佳為0.025%以下、更佳為0.022%以下。 Nb is precipitated as a carbonitride (including carbide), and the produced carbonitride is effective at a portion where diffusible hydrogen is trapped, and has an effect of suppressing stress corrosion cracking. In order to obtain such an effect, Nb must be contained in an amount of 0.003% or more. on the other hand, When the content exceeds 0.030%, a coarse carbonitride is precipitated, which is a starting point of destruction. Further, there is a phenomenon in which precipitates are coarsened and the base material toughness is deteriorated. Therefore, in the case of containing Nb, it is 0.003% to 0.030%. It is preferably 0.005% or more, more preferably 0.007% or more. It is preferably 0.025% or less, more preferably 0.022% or less.
V:0.03%~0.10% V: 0.03%~0.10%
V是作為碳氮化物而析出,所生成的碳氮化物於擴散性氫的捕獲部位有效,具有抑制應力腐蝕破裂的效果的元素。為了獲得此種效果,V必須含有0.03%以上。另一方面,若含有超過0.10%,則存在析出粗大的碳氮化物,成為破壞的起點的現象。而且,存在析出物粗大化,使母材韌性劣化的現象。因此,在含有V的情況下為0.03%~0.10%。較佳為0.04%以上、更佳為0.05%以上。較佳為0.09%以下、更佳為0.08%以下。 V is precipitated as a carbonitride, and the produced carbonitride is effective at a portion where diffusible hydrogen is trapped, and has an effect of suppressing stress corrosion cracking. In order to obtain such an effect, V must contain 0.03% or more. On the other hand, when the content is more than 0.10%, a coarse carbonitride is precipitated, which is a starting point of destruction. Further, there is a phenomenon in which precipitates are coarsened and the base material toughness is deteriorated. Therefore, in the case of containing V, it is 0.03% to 0.10%. It is preferably 0.04% or more, more preferably 0.05% or more. It is preferably 0.09% or less, more preferably 0.08% or less.
Ti:0.003%~0.040% Ti: 0.003%~0.040%
Ti是作為氮化物或碳氮化物而析出,所生成的氮化物或碳氮化物於擴散性氫的捕獲部位有效,具有抑制應力腐蝕破裂的效果的元素。為了獲得此種效果,Ti必須含有0.003%以上。另一方面,若含有超過0.040%,則存在析出物粗大化,使母材韌性劣化的現象。而且,存在析出粗大的碳氮化物,成為破壞的起點的現象。因此,在含有Ti的情況下為0.003%~0.040%。較佳為0.005%以上、更佳為0.007%以上。較佳為0.035%以下、更佳為0.032%以下。 Ti is precipitated as a nitride or a carbonitride, and the produced nitride or carbonitride is effective at a portion where diffusible hydrogen is trapped, and has an effect of suppressing stress corrosion cracking. In order to obtain such an effect, Ti must be contained in an amount of 0.003% or more. On the other hand, when the content is more than 0.040%, the precipitates are coarsened and the toughness of the base material is deteriorated. Further, there is a phenomenon in which coarse carbonitrides are precipitated and become a starting point of destruction. Therefore, in the case of containing Ti, it is 0.003% to 0.040%. It is preferably 0.005% or more, more preferably 0.007% or more. It is preferably 0.035% or less, more preferably 0.032% or less.
剩餘部分是鐵及不可避免的雜質。作為不可避免的雜質,可列舉O或H等,若合計為0.01%以下則可容許。 The remainder is iron and inevitable impurities. Examples of the unavoidable impurities include O or H, and the like is acceptable if the total amount is 0.01% or less.
藉由以上的必需元素而獲得本發明的目標特性。在本發明中,為了使強度及低溫韌性進一步提高,除了所述必需元素以外,亦可視需要含有下述元素。 The target characteristics of the present invention are obtained by the above essential elements. In the present invention, in order to further improve the strength and low-temperature toughness, in addition to the essential elements, the following elements may be contained as needed.
Mo:0.05%~2.0%、W:0.05%~2.0%的一種或兩種Mo:0.05%~2.0% Mo: 0.05% to 2.0%, W: 0.05% to 2.0% of one or two Mo: 0.05% to 2.0%
Mo是對於母材的高強度化而言有用的元素,可視需要含有。為了獲得此種效果,較佳的是含有0.05%以上的Mo。另一方面,若含有超過2.0%,則存在對韌性及耐焊接破裂性造成不良影響的情況,因此Mo較佳為2.0%以下。因此,在含有Mo的情況下為0.05%~2.0%。 Mo is an element useful for increasing the strength of the base material, and may be contained as needed. In order to obtain such an effect, it is preferred to contain 0.05% or more of Mo. On the other hand, when it is more than 2.0%, the toughness and the weld fracture resistance may be adversely affected. Therefore, Mo is preferably 2.0% or less. Therefore, in the case of containing Mo, it is 0.05% to 2.0%.
W:0.05%~2.0% W: 0.05%~2.0%
W是對於母材的高強度化而言有用的元素,可視需要而含有。為了獲得此種效果,較佳的是含有0.05%以上的W。另一方面,若含有超過2.0%,則存在對韌性及耐焊接破裂性造成不良影響的情況,因此W較佳為2.0%以下。因此,在含有W的情況下為0.05%~2.0%。更佳為0.07%以上。更佳為1.5%以下。 W is an element useful for increasing the strength of the base material, and may be contained as needed. In order to obtain such an effect, it is preferred to contain 0.05% or more of W. On the other hand, when it is more than 2.0%, the toughness and the weld fracture resistance may be adversely affected. Therefore, W is preferably 2.0% or less. Therefore, in the case of containing W, it is 0.05% to 2.0%. More preferably, it is 0.07% or more. More preferably, it is 1.5% or less.
Ca:0.0005%~0.0050%、Mg:0.0005%~0.0050%、REM:0.0010%~0.0200%的一種或兩種以上 Ca: 0.0005% to 0.0050%, Mg: 0.0005% to 0.0050%, REM: 0.0010% to 0.0200%, one or more
Ca:0.0005%~0.0050% Ca: 0.0005%~0.0050%
Ca是對於夾雜物的形態控制而言有用的元素,可視需要而含 有。所謂「夾雜物的形態控制」是指使伸長的硫化物系夾雜物成為粒狀的夾雜物。經由該夾雜物的形態控制,使延性、韌性、耐硫化物應力腐蝕破裂性提高。為了獲得此種效果,較佳為含有0.0005%以上的Ca。另一方面,若含有超過0.0050%,則存在非金屬夾雜物量增加,反而造成延性、韌性、耐硫化物應力腐蝕破裂性降低的情況。而且,存在於經濟上變得不利的情況。因此,在含有Ca的情況下為0.0005%~0.0050%。更佳為0.0010%以上。更佳為0.0040%以下。 Ca is an element useful for the morphology control of inclusions, and may be included as needed. Have. The "morphological control of inclusions" means inclusions in which elongated sulfide-based inclusions are granular. Through the morphology control of the inclusions, ductility, toughness, and sulfide stress corrosion cracking resistance are improved. In order to obtain such an effect, it is preferred to contain 0.0005% or more of Ca. On the other hand, when the content exceeds 0.0050%, the amount of non-metallic inclusions increases, and conversely, toughness, and sulfide stress corrosion cracking resistance may be lowered. Moreover, there are cases where the economy becomes unfavorable. Therefore, in the case of containing Ca, it is 0.0005% to 0.0050%. More preferably, it is 0.0010% or more. More preferably, it is 0.0040% or less.
Mg:0.0005%~0.0050% Mg: 0.0005%~0.0050%
Mg作為有助於改善耐硫化物應力腐蝕破裂性的元素而言有用,可視需要而含有。為了獲得此種效果,較佳為含有0.0005%以上的Mg。另一方面,即使含有超過0.0050%,亦存在所述效果飽和,無法期待與含量相符的效果的情況。而且,存在於經濟上變得不利的情況。因此,在含有Mg的情況下為0.0005%~0.0050%。更佳為0.0010%以上。更佳為0.0040%以下。 Mg is useful as an element which contributes to improvement of sulfide stress corrosion cracking resistance, and may be contained as needed. In order to obtain such an effect, it is preferred to contain 0.0005% or more of Mg. On the other hand, even if the content exceeds 0.0050%, the effect is saturated, and the effect corresponding to the content cannot be expected. Moreover, there are cases where the economy becomes unfavorable. Therefore, in the case of containing Mg, it is 0.0005% to 0.0050%. More preferably, it is 0.0010% or more. More preferably, it is 0.0040% or less.
REM:0.0010%~0.0200% REM: 0.0010%~0.0200%
REM作為有助於改善耐硫化物應力腐蝕破裂性的元素而言有用,可視需要而含有。為了獲得此種效果,較佳為含有0.0010%以上的REM。另一方面,即使含有超過0.0200%,亦存在所述效果飽和,無法期待與含量相符的效果的情況。因此,在含有REM的情況下為0.0010%~0.0200%。更佳為0.0020%以上。更佳為0.0150%以下。 REM is useful as an element that contributes to the improvement of sulfide stress corrosion cracking resistance, and may be contained as needed. In order to obtain such an effect, it is preferred to contain 0.0010% or more of REM. On the other hand, even if it contains more than 0.0200%, the effect is saturated, and the effect corresponding to the content cannot be expected. Therefore, in the case of containing REM, it is 0.0010% to 0.0200%. More preferably, it is 0.0020% or more. More preferably, it is 0.0150% or less.
[微組織] [micro organization]
其次,關於本發明的鋼板的重要要件的鋼板表面附近的微組織加以說明。 Next, the microstructure of the vicinity of the surface of the steel sheet, which is an important requirement of the steel sheet of the present invention, will be described.
鋼板表面下0.5mm的微組織以沃斯田體為基質相,該沃斯田體中的面積率的25%以上是圓等效直徑為10μm以上,且長徑與短徑的縱橫比為3以上。 The microstructure of 0.5 mm under the surface of the steel sheet is the matrix phase of the Worth field. The area ratio of the Worth field is 25% or more, the circle equivalent diameter is 10 μm or more, and the aspect ratio of the long diameter to the short diameter is 3. the above.
在本發明中,將鋼板表面下0.5mm的微組織的基質相設為沃斯田體。而且,在該沃斯田體中具有面積率為25%以上的圓等效直徑為10μm以上、且長徑與短徑的縱橫比為3以上的沃斯田體,藉此作為擴散性氫的捕獲部位而有效地起作用。藉此可使應力腐蝕破裂的抑制格外提高。較佳的是面積率為30%以上。另一方面,若面積率超過95%,則存在產生母材韌性劣化的情況。較佳為90%以下。更佳為85%以下。 In the present invention, the matrix phase of the microstructure of 0.5 mm below the surface of the steel sheet is set as the Worthian body. Further, in the Voss field, a Worth field having an area ratio of 25% or more and an equivalent diameter of 10 μm or more and an aspect ratio of a long diameter to a short diameter of 3 or more is used as the diffusible hydrogen. The capture site works effectively. Thereby, the suppression of stress corrosion cracking can be particularly improved. Preferably, the area ratio is 30% or more. On the other hand, when the area ratio exceeds 95%, the toughness of the base material may be deteriorated. It is preferably 90% or less. More preferably, it is 85% or less.
若圓等效直徑不足10μm、或長徑與短徑的縱橫比不足3,則無法獲得所述效果。再者,所述沃斯田體的圓等效直徑、面積率、縱橫比可藉由後述的實施例中所記載的方法而測定。 If the circle equivalent diameter is less than 10 μm, or the aspect ratio of the long diameter to the short diameter is less than 3, the effect cannot be obtained. Further, the circle equivalent diameter, the area ratio, and the aspect ratio of the Vostian body can be measured by the method described in the examples below.
在本發明中,所謂「鋼板表面下0.5mm」是表示自鋼板的表背面起在板厚方向上為0.5mm的位置。不僅表示成品的單純的表面,亦表示對可對鋼板表面測定結晶積體度的面進行處理後的面,例如在鋼板的最表面被鱗片(scale)覆蓋時等,表示將其除去之後的面。 In the present invention, the term "0.5 mm under the surface of the steel sheet" means a position of 0.5 mm in the thickness direction from the front and back surfaces of the steel sheet. The surface which is the surface of the surface of the steel sheet, and the surface which measures the crystallographic degree of the steel sheet is not only the surface which is the surface of the steel sheet, for example, when the outermost surface of the steel sheet is covered with scales, the surface after removal is shown. .
再者,在本發明中,在自鋼板表面下0.5mm的位置起± 5%的範圍中即使存在所述微組織,亦可同樣地獲得所述效果。 Furthermore, in the present invention, the position is 0.5 mm from the surface of the steel sheet. The effect can be similarly obtained even in the range of 5% even if the microstructure is present.
關於鋼板表面下0.5mm的微組織,進而在組織中具有合計2×102個/mm2以上的圓等效直徑為0.01μm~0.5μm的含有Nb、V、Ti的一種或兩種以上的碳化物、氮化物及碳氮化物。 In the microstructure of 0.5 mm under the surface of the steel sheet, one or more types of Nb, V, and Ti having a circle equivalent diameter of 2 × 10 2 /mm 2 or more and having a circle equivalent diameter of 0.01 μm to 0.5 μm are further contained in the structure. Carbides, nitrides and carbonitrides.
關於本發明的鋼板表面下0.5mm的微組織中的含有Nb、V、Ti的一種或兩種以上的碳化物、氮化物、碳氮化物(以下稱為「Nb、V、Ti系析出物」)的存在狀態加以說明。再者,所謂「含有Nb、V、Ti的一種或兩種以上的碳化物、氮化物、碳氮化物」是指含有Nb、V、Ti的一種或兩種以上的碳化物,含有Nb、V、Ti的一種或兩種以上的氮化物,含有Nb、V、Ti的一種或兩種以上的碳氮化物。 One or two or more kinds of carbides, nitrides, and carbonitrides containing Nb, V, and Ti in the microstructure of 0.5 mm under the surface of the steel sheet of the present invention (hereinafter referred to as "Nb, V, Ti-based precipitates" The existence status of ) is explained. In addition, "one or two or more kinds of carbides, nitrides, and carbonitrides containing Nb, V, and Ti" mean one or two or more kinds of carbides containing Nb, V, and Ti, and contain Nb and V. One or two or more nitrides of Ti contain one or two or more kinds of carbonitrides of Nb, V, and Ti.
Nb、V、Ti系析出物的粒徑是圓等效直徑為0.01μm~0.5μm。若不足0.01μm,則作為擴散性氫的捕獲部位而抑制氫脆化破裂的效果飽和。而且,在實際製造中管理為不足0.01μm會使製造負荷極度增大,造成製造成本上升。另一方面,若超過0.5μm,則低溫韌性降低。而且,無法獲得作為擴散性氫的捕獲部位而抑制氫脆化破裂的效果。較佳為0.03μm以上。較佳為0.4μm以下。 The particle diameter of the Nb, V, and Ti-based precipitates is a circle equivalent diameter of 0.01 μm to 0.5 μm. When it is less than 0.01 μm, the effect of suppressing hydrogen embrittlement cracking as a trapping portion of diffusible hydrogen is saturated. Further, management in the actual production of less than 0.01 μm causes an extremely large manufacturing load, resulting in an increase in manufacturing cost. On the other hand, when it exceeds 0.5 μm, the low temperature toughness is lowered. Further, the effect of suppressing hydrogen embrittlement cracking as a trapping portion of diffusible hydrogen cannot be obtained. It is preferably 0.03 μm or more. It is preferably 0.4 μm or less.
所述粒徑的Nb、V、Ti系析出物的合計若在鋼板表面下0.5mm的微組織中不足2×102個/mm2,則無法獲得作為擴散性氫的捕獲部位而抑制氫脆化破裂的效果。因此為2×102個/mm2以上。較佳為5×102個/mm2以上。再者,所述Nb、V、Ti系析出物的個 數密度及圓等效直徑可藉由後述的實施例中所記載的方法而測定。 When the total of the Nb, V, and Ti-based precipitates having the particle diameter is less than 2 × 10 2 /mm 2 in the microstructure of 0.5 mm under the surface of the steel sheet, the trapping portion as the diffusible hydrogen cannot be obtained and the hydrogen embrittlement is suppressed. The effect of rupture. Therefore, it is 2 × 10 2 /mm 2 or more. It is preferably 5 × 10 2 /mm 2 or more. Further, the number density and the circle equivalent diameter of the Nb, V, and Ti-based precipitates can be measured by the method described in the examples below.
再者,若在鋼板表面下0.5mm的微組織中,除了沃斯田體以外,亦混合存在有麻田散體等組織,則低溫韌性降低。因此,較佳為麻田散體等組織的面積率少,在混合存在的情況下,理想的是面積率的合計相對於鋼板整體而言為10%以下。 Further, in the microstructure of 0.5 mm under the surface of the steel sheet, in addition to the Worth field, a structure such as a granule of the genus is mixed, and the low-temperature toughness is lowered. Therefore, it is preferable that the area ratio of the tissue such as the granules is small, and when it is mixed, it is preferable that the total area ratio is 10% or less with respect to the entire steel sheet.
[製造條件] [Manufacture conditions]
其次,關於本發明的鋼板的製造方法而加以說明。再者,本發明的鋼板適合的是板厚為4mm以上的高錳鋼板。 Next, a method of producing the steel sheet of the present invention will be described. Further, the steel sheet of the present invention is preferably a high manganese steel sheet having a thickness of 4 mm or more.
本發明的鋼板是藉由如下方式而獲得,將具有所述成分組成的鋼原材料加熱至如下之溫度區域,亦即於將Tx(x=Nb、V或Ti)設為後述的式(1)~式(3)所示的溫度時,以式(1)~式(3)所定義的Tx(℃)的任意一個以上表示而言,鋼原材料的表面溫度為(Tx-50)℃以上、(Tx+200)℃以下的溫度區域;進行精軋結束溫度為750℃以上、1000℃以下的熱軋而製造鋼板;其後,以自(精軋結束溫度-50℃)或冷卻開始溫度的任意較低的溫度至650℃的鋼板表面的平均冷卻速度為1.0℃/s以上進行冷卻。 The steel sheet according to the present invention is obtained by heating a steel material having the above-described composition to a temperature region in which Tx (x = Nb, V or Ti) is expressed as a formula (1) to be described later. When the temperature is represented by the formula (3), the surface temperature of the steel material is (Tx-50) ° C or more, as indicated by any one or more of Tx (° C.) defined by the formulas (1) to (3). (Tx + 200) °C or less; a steel sheet is produced by hot rolling at a finishing finish temperature of 750 ° C or higher and 1000 ° C or lower; and thereafter, from (finishing finish temperature -50 ° C) or cooling start temperature The average cooling rate of the surface of the steel sheet of any lower temperature to 650 ° C is 1.0 ° C / s or more for cooling.
以下進行詳細說明。再者,在說明中,關於溫度的「℃」的表示是指鋼板表面或鋼原材料的表面的溫度。 The details are described below. In the description, the expression "°C" of the temperature means the temperature of the surface of the steel sheet or the surface of the steel material.
本發明的高錳鋼板可藉由轉爐、電爐等公知的熔製方法對具有所述成分組成的熔鋼進行熔製。而且,亦可於真空脫氣爐 中進行2次精煉。較佳的是其後藉由連續鑄造法或造塊-分塊軋製法等公知的鑄造方法製成規定尺寸的鋼坯等鋼原材料。 The high manganese steel sheet of the present invention can be melted by a known melting method such as a converter or an electric furnace to have a molten steel having the above composition. Moreover, it can also be used in a vacuum degassing furnace. 2 times of refining. It is preferable to form a steel material such as a steel slab of a predetermined size by a known casting method such as a continuous casting method or a block-block rolling method.
鑄造後鋼坯:將所獲得的鋼原材料並不冷卻至室溫或冷卻至室溫後加熱為如下的溫度區域,亦即於將Tx(x=Nb、V或Ti)設為式(1)~式(3)所示的溫度時,以式(1)~式(3)所定義的Tx(℃)的任意一個以上表示而言,鋼原材料的表面溫度為(Tx-50)℃以上、(Tx+200)℃以下的溫度區域TNb(℃)=7500/{3.0-log10([%Nb]×[%C])}-273…(1) After casting the billet: the obtained steel material is not cooled to room temperature or cooled to room temperature and then heated to the following temperature range, that is, Tx (x=Nb, V or Ti) is set to formula (1)~ In the case of the temperature represented by the formula (3), the surface temperature of the steel material is (Tx-50) ° C or more, as indicated by any one or more of Tx (°C) defined by the formulas (1) to (3). Tx+200) Temperature range below °C T Nb (°C)=7500/{3.0-log 10 ([%Nb]×[%C])}-273...(1)
Tv(℃)=10800/{7.2-log10([%V]×[%C])}-273…(2) Tv(°C)=10800/{7.2-log 10 ([%V]×[%C])}-273...(2)
TTi(℃)=7000/{2.8-log10([%Ti]×[%C])}-273…(3) T Ti (°C)=7000/{2.8-log 10 ([%Ti]×[%C])}-273...(3)
此處,[%Nb]、[%V]、[%Ti]及[%C]分別表示鋼中的Nb、V、Ti及C的含量(質量%)。在並未含有的元素的情況下,將式中的元素記號設為0而進行計算。 Here, [%Nb], [%V], [%Ti], and [%C] respectively represent the content (% by mass) of Nb, V, Ti, and C in the steel. In the case of an element that is not contained, the calculation is performed by setting the element symbol in the formula to zero.
若加熱溫度不足(Tx-50)℃,則熱軋下的變形阻力變高,變得難以較大地獲得每一次通過的壓下量,因此軋製通過數增加,導致軋製效率降低,且存在無法壓接鋼原材料(鋼坯)中的鑄造缺陷的情況。進而,在熔製階段,在鋼中不均一地結晶的包含Nb、V及Ti的結晶物亦殘存於軋製結束後的鋼板中,未能獲得所期望的包含Nb、V及Ti的析出物,耐應力腐蝕破裂性降低。 When the heating temperature is less than (Tx - 50) ° C, the deformation resistance under hot rolling becomes high, and it becomes difficult to obtain a large amount of reduction per pass, so that the number of rolling passes increases, and the rolling efficiency is lowered, and there is It is not possible to crimp the case of casting defects in steel raw materials (steel billets). Further, in the melting stage, crystals containing Nb, V, and Ti which are not uniformly crystallized in the steel remain in the steel sheet after the rolling, and the desired precipitates containing Nb, V, and Ti are not obtained. , resistance to stress corrosion cracking is reduced.
另一方面,若加熱溫度超過(Tx+200)℃,則容易由於加熱時的鱗片而產生表面瑕疵,軋製後的修整負荷增大。而且,鋼原材料的表面過度地脫碳,軋製後的鋼板表面成為麻田散體, 彎曲性或氫脆性降低。進而由於沃斯田體粒粗大化而未能獲得目標的微組織。 On the other hand, when the heating temperature exceeds (Tx + 200) °C, surface flaws are likely to occur due to the scales during heating, and the dressing load after rolling increases. Moreover, the surface of the steel raw material is excessively decarburized, and the surface of the steel sheet after rolling becomes a granulated body. Bending or hydrogen embrittlement is reduced. Further, the target micro-tissue was not obtained due to the coarsening of the Worthite body.
因此,鋼原材料的加熱溫度為(Tx-50)℃以上、(Tx+200)℃以下。較佳為(Tx-30)℃以上。較佳為(Tx+180)℃以下。再者,在直送軋製的情況下,鋼原材料在(Tx-50)℃以上、(Tx+200)℃以下開始熱軋。 Therefore, the heating temperature of the steel material is (Tx-50) ° C or more and (Tx + 200) ° C or less. It is preferably (Tx-30) °C or more. It is preferably (Tx + 180) ° C or less. Further, in the case of direct rolling, the steel material is hot rolled at (Tx-50) ° C or higher and (Tx + 200) ° C or lower.
再者,本發明的所謂「加熱至如下之溫度區域,亦即於將Tx(x=Nb、V或Ti)設為式(1)~式(3)所示的溫度時,以式(1)~式(3)所定義的Tx(℃)的任意一個以上表示而言,鋼原材料的表面溫度為(Tx-50)℃以上、(Tx+200)℃以下的溫度區域」是表示例如在含有Nb與V此兩種作為所述成分組成的情況下,加熱溫度若滿足(TNb-50)℃以上、(TNb+200)℃以下或(Tv-50)℃以上、(Tv+200)℃以下的任意一個以上即可。亦即,可選擇任意的加熱溫度。 Further, in the present invention, "heating to a temperature range, that is, when Tx (x = Nb, V or Ti) is set to a temperature represented by the formulas (1) to (3), Any one or more of Tx (°C) defined by the formula (3) indicates that the surface temperature of the steel material is (Tx-50) ° C or more and (Tx + 200) ° C or less. When both of Nb and V are contained as the component composition, the heating temperature satisfies (T Nb -50) ° C or more, (T Nb +200) ° C or less, or (Tv - 50) ° C or more, (Tv + 200). Any one or more below °C. That is, any heating temperature can be selected.
熱軋:在粗軋後,將精軋的精軋結束溫度設為750℃以上、1000℃以下而製成所期望的板厚的鋼板。 Hot rolling: After the rough rolling, the finish rolling finishing temperature of the finish rolling is set to 750 ° C or more and 1000 ° C or less to obtain a steel sheet having a desired thickness.
若熱軋的精軋結束溫度超過1000℃,則容易進行鋼板表面附近的沃斯田體的再結晶,未能獲得所期望的微組織,導致耐應力腐蝕破裂性降低。另一方面,若使精軋結束溫度不足750℃,則熱變形阻力過度變高,對軋製機的負荷變大。而且,軋製效率降低而導致製造成本上升。因此,熱軋的精軋結束溫度為750℃以上、1000℃以下。較佳為800℃以上。較佳為950℃以下。 When the finishing rolling temperature of hot rolling exceeds 1000 ° C, recrystallization of the Worth field near the surface of the steel sheet is facilitated, and the desired microstructure is not obtained, resulting in a decrease in stress corrosion cracking resistance. On the other hand, when the finish rolling finishing temperature is less than 750 ° C, the thermal deformation resistance is excessively increased, and the load on the rolling mill is increased. Moreover, the rolling efficiency is lowered to cause an increase in manufacturing cost. Therefore, the finishing rolling temperature of hot rolling is 750 ° C or more and 1000 ° C or less. It is preferably 800 ° C or more. It is preferably 950 ° C or lower.
精軋的850℃以上、(Tx-50)℃以下的溫度區域的累積壓縮比為10%以上、50%以下(適宜條件) The cumulative compression ratio of the temperature range of 850 ° C or more and (Tx-50) ° C or less in the finish rolling is 10% or more and 50% or less (suitable conditions)
850℃以上、(Tx-50)℃以下的溫度區域的累積壓縮比若不足10%,則未能獲得目標的微組織。另一方面,若超過50%,則軋製時的效率降低。再者,累積壓縮比是將在精軋中,成為850℃以上、(Tx-50)℃以下的溫度區域的各軋製通過的壓縮比分別相加而進行合計者。 When the cumulative compression ratio of the temperature region of 850 ° C or more and (Tx-50) ° C or less is less than 10%, the target microstructure is not obtained. On the other hand, when it exceeds 50%, the efficiency at the time of rolling falls. In addition, the cumulative compression ratio is obtained by adding the compression ratios of the respective rolling passes in the temperature range of 850 ° C or more and (T x 50) ° C or less in the finish rolling.
在精軋結束後,自(精軋結束溫度-50℃)或冷卻開始溫度的任意較低的溫度至650℃,以鋼板表面的平均冷卻速度為1.0℃/s以上進行冷卻 After finishing finishing, cooling from any lower temperature (finishing finish temperature -50 ° C) or cooling start temperature to 650 ° C, cooling at an average cooling rate of the steel sheet surface of 1.0 ° C / s or more
若鋼板表面的平均冷卻速度不足1.0℃/s,則在高溫下長時間地滯留,因此碳化物粗大化,因此強度降低。不僅如此,而且生成Cr碳化物,造成韌性及應力腐蝕破裂性降低。因此,平均冷卻速度為1.0℃/s以上。較佳為2.0℃/s以上。另一方面,平均冷卻速度若超過150.0℃/s,則變得難以確保鋼板形狀。 When the average cooling rate of the surface of the steel sheet is less than 1.0 ° C / s, it stays at a high temperature for a long period of time, so that the carbide is coarsened, so the strength is lowered. Not only that, but also the formation of Cr carbides causes a decrease in toughness and stress corrosion cracking. Therefore, the average cooling rate is 1.0 ° C / s or more. It is preferably 2.0 ° C / s or more. On the other hand, if the average cooling rate exceeds 150.0 ° C / s, it becomes difficult to secure the shape of the steel sheet.
因此,平均冷卻速度較佳為120.0℃/s以下。更佳為100.0℃/s以下。此處所謂「平均冷卻速度」是在精軋結束後,自(精軋結束溫度-50℃)或冷卻開始溫度的任意較低溫度至650℃的冷卻速度的平均。 Therefore, the average cooling rate is preferably 120.0 ° C / s or less. More preferably, it is 100.0 ° C / s or less. Here, the "average cooling rate" is an average of the cooling rate from any lower temperature (finishing finish temperature - 50 ° C) or cooling start temperature to 650 ° C after completion of finish rolling.
在本發明中,新發現控制冷卻中的平均冷卻速度可有效地抑制冷卻中的Cr碳化物析出,藉此使耐應力腐蝕破裂性提高。 In the present invention, it has been newly found that controlling the average cooling rate in cooling can effectively suppress the precipitation of Cr carbides during cooling, thereby improving the stress corrosion cracking resistance.
再者,精軋結束溫度~(精軋結束溫度-50℃)的溫度 區域的平均冷卻速度並無特別規定,但自可促進Nb、V、Ti系析出物的析出考慮,較佳為1.0℃/s以下。而且,不足650℃的平均冷卻速度亦無特別規定,但自防止鋼板變形的觀點考慮,較佳為不足100.0℃/s。更佳為80.0℃/s以下。 Furthermore, the finish rolling temperature is ~ (the finish rolling temperature is -50 ° C) Although the average cooling rate of the region is not particularly limited, it is preferably 1.0 ° C / s or less from the viewpoint of promoting precipitation of Nb, V, and Ti-based precipitates. Further, the average cooling rate of less than 650 ° C is not particularly limited, but from the viewpoint of preventing deformation of the steel sheet, it is preferably less than 100.0 ° C / s. More preferably, it is 80.0 ° C / s or less.
[實施例] [Examples]
以下,藉由實施例對本發明加以詳細說明。再者,本發明並不限定於以下的實施例。 Hereinafter, the present invention will be described in detail by way of examples. Furthermore, the invention is not limited to the following examples.
藉由轉爐-盛桶精煉-連續鑄造法,將製備為表1中所示的各種成分組成的鋼坯(原材料厚度:250mm~300mm)加熱至(Tx-50)℃以上、(Tx+200)℃以下(x=Nb、V或Ti)後,將表2中所示的製造條件及精軋的850℃以上、(Tx-50)℃以下的溫度區域的累積壓縮比設為40%而實施熱軋,然後在表2中所示的製造條件下進行冷卻。再者,將Nb、V或Ti的(Tx-50)℃、(Tx+200)℃表示於表1中。 The billet (raw material thickness: 250 mm to 300 mm) prepared with various components shown in Table 1 is heated to (Tx-50) °C or higher (Tx + 200) °C by a converter-barrel refining-continuous casting method. After (x=Nb, V or Ti), the production conditions shown in Table 2 and the cumulative compression ratio of the temperature range of 850 ° C or more and (Tx-50) ° C or less of the finish rolling were set to 40%, and heat was applied. It was rolled and then cooled under the manufacturing conditions shown in Table 2. Further, (Tx-50) ° C and (Tx + 200) ° C of Nb, V or Ti are shown in Table 1.
關於所獲得的板厚為12mm~80mm的熱軋鋼板,以下述要領實施微組織調查、母材拉伸試驗、母材韌性、應力腐蝕破裂性試驗。 Regarding the obtained hot-rolled steel sheets having a thickness of 12 mm to 80 mm, a microstructure investigation, a base material tensile test, a base material toughness, and a stress corrosion cracking test were carried out in the following manner.
(1)微組織 (1) Micro organization
微組織的調查是關於所獲得的各鋼板的板厚表面下0.5mm的位置的與軋製方向平行的剖面,採取微組織觀察用樣品,藉由焦亞硫酸鈉水溶液(10g Na2S2O5+95ml水溶液)進行浸漬腐蝕後,藉由光學顯微鏡以500倍的倍率對組織進行5視野攝影。其 後,對於所獲得的組織圖像,使用圖像分析裝置而求出沃斯田體的面積率、圓等效直徑及縱橫比。 The investigation of the microstructure was performed on a section perpendicular to the rolling direction at a position of 0.5 mm below the thickness of each steel sheet obtained, and a sample for microstructural observation was taken by an aqueous sodium metabisulfite solution (10 g Na 2 S 2 O 5 + After immersion etching in 95 ml of an aqueous solution, the tissue was subjected to 5-field imaging at a magnification of 500 times by an optical microscope. Thereafter, the area ratio, the circle equivalent diameter, and the aspect ratio of the Worth field body were obtained using the image analysis device for the obtained tissue image.
沃斯田體的面積率 Area ratio of the Worth field
沃斯田體的面積率是對沃斯田體進行蝕刻,以500倍對組織拍攝相片,追蹤沃斯田體晶界,藉由圖像分析而求出10μm以上的沃斯田體的面積相對於沃斯田體面積的整體面積的比例。 The area ratio of the Worth field is to etch the Worth field, take photos of the tissue 500 times, track the grain boundary of the Worthfield, and find the area of the Worth field above 10 μm by image analysis. The proportion of the total area of the area of the field.
沃斯田體的圓等效直徑 Round equivalent diameter of the Worth field
沃斯田體的結晶粒徑、亦即沃斯田體的圓等效直徑是對所述組織圖像使用圖像分析,測定各個沃斯田體的面積。根據各個面積算出圓等效直徑。 The crystal grain size of the Worth field, that is, the circle equivalent diameter of the Worth field, is an image analysis of the tissue image, and the area of each Worth field is measured. The circle equivalent diameter is calculated from each area.
沃斯田體粒的縱橫比 Aspect ratio of Worthfield body particles
沃斯田體粒的縱橫比是藉由光學顯微鏡觀察由於所述腐蝕而使沃斯田體晶界出現的組織,關於各個沃斯田體粒算出與最長直徑(長徑)正交的最寬寬度(短徑)相對於長徑的比。 The aspect ratio of the Wolsfield body particles is obtained by observing the structure of the Worth field grain boundary due to the corrosion by an optical microscope, and calculating the widest width orthogonal to the longest diameter (long diameter) for each Worthfield body particle ( The ratio of the short diameter to the long diameter.
Nb、V、Ti系析出物的圓等效直徑 The circle equivalent diameter of Nb, V, Ti precipitates
Nb、V、Ti系析出物的圓等效直徑的調查是關於各鋼板的板厚表面下0.5mm的位置的與軋製方向平行的剖面,藉由穿透式電子顯微鏡進行10視野的50000倍攝影,對該組織圖像使用圖像分析而測定各個Nb、V、Ti系析出物的面積。根據各個面積算出Nb、V、Ti系析出物的圓等效直徑。 The round-equivalent diameter of the Nb, V, and Ti-based precipitates is a cross section parallel to the rolling direction at a position of 0.5 mm below the thickness surface of each steel sheet, and 50,000 times the 10 fields of view by a transmission electron microscope. Photography, the area of each Nb, V, and Ti-based precipitate was measured using image analysis on the tissue image. The circle equivalent diameter of the Nb, V, and Ti-based precipitates was calculated from the respective areas.
Nb、V、Ti系析出物的個數密度 Number density of Nb, V, Ti precipitates
Nb、V、Ti系析出物的個數密度的調查是關於各鋼板的板厚 表面下0.5mm的位置的與軋製方向平行的剖面,藉由穿透式電子顯微鏡進行10視野的50000倍攝影,調查每1mm2的圓等效直徑為0.01μm~0.5μm的Nb、V、Ti系析出物的個數,求出Nb、V、Ti系析出物的合計個數密度。 The number density of the Nb, V, and Ti-based precipitates is a cross section parallel to the rolling direction at a position of 0.5 mm below the thickness of each steel sheet, and 50,000-times of 10 fields of view is performed by a transmission electron microscope. The number of Nb, V, and Ti-based precipitates having a circle-equivalent diameter of from 0.01 μm to 0.5 μm per 1 mm 2 was investigated, and the total number density of Nb, V, and Ti-based precipitates was determined.
(2)母材拉伸特性 (2) Base material tensile properties
自所獲得的各鋼板採取JIS 5號拉伸試片,依據JIS Z 2241(1998年)的規定而實施拉伸試驗,調查拉伸特性。在本發明中,將降伏強度為400MPa以上設為母材拉伸特性優異(本發明範圍內)。再者,本發明的母材拉伸特性優異是指抗拉強度為800MPa以上、總伸長為30%以上。 A JIS No. 5 tensile test piece was used for each of the obtained steel sheets, and a tensile test was carried out in accordance with the regulations of JIS Z 2241 (1998) to investigate the tensile properties. In the present invention, the lodging strength of 400 MPa or more is excellent in the tensile properties of the base material (within the scope of the present invention). Further, the excellent tensile properties of the base material of the present invention means that the tensile strength is 800 MPa or more and the total elongation is 30% or more.
(3)母材韌性 (3) Base metal toughness
自板厚超過20mm的各鋼板的板厚1/4位置、或板厚20mm以下的各鋼板的板厚1/2位置的與軋製方向垂直的方向,依據JIS Z 2202(1998年)的規定採取夏比V型缺口試片,依據JIS Z 2242(1998年)的規定關於各鋼板而實施3根的夏比衝擊試驗,求出-196℃下的吸收能量,評價母材韌性。在本發明中,將3根吸收能量(vE-196)的平均值為50J以上設為母材韌性優異(本發明範圍內)。進而較佳為吸收能量(vE-196)的平均值為100J以上。 The direction perpendicular to the rolling direction of each steel sheet of the steel plate having a thickness of more than 20 mm and the plate thickness of 1/2 of the plate thickness of 20 mm or less is perpendicular to the rolling direction, in accordance with JIS Z 2202 (1998). A Charpy V-notch test piece was used, and three Charpy impact tests were performed on each steel sheet in accordance with JIS Z 2242 (1998), and the absorbed energy at -196 ° C was determined to evaluate the base material toughness. In the present invention, the average value of the three absorbed energy (vE- 196 ) is 50 J or more, which is excellent in the base material toughness (within the scope of the present invention). Further preferably, the average value of the absorbed energy (vE - 196 ) is 100 J or more.
(4)應力腐蝕破裂性 (4) Stress corrosion cracking
應力腐蝕破裂性試驗是依據美國國際腐蝕工程師協會(National Association of Corrosion Engineers,NACE)標準TM0111-2011基準的慢應變速率試驗方法(Slow Strain Rate Test Method)而實施。使用試片形狀為附有類型A圓棒切口的試片,在溫度為23℃下浸漬於人工海水(氯化物離子濃度為18000ppm)中,在4×10-7inch/sec.的應變速度下實施等速拉伸試驗。在本發明中,將破斷應力為500MPa以上設為耐應力腐蝕破裂性優異(本發明範圍內)。進而較佳為破斷應力為600MPa以上。 The stress corrosion cracking test was carried out in accordance with the Slow Strain Rate Test Method of the National Association of Corrosion Engineers (NACE) Standard TM0111-2011. Using a test piece in the shape of a test piece with a type A round bar cut, immersed in artificial seawater (chloride ion concentration of 18000 ppm) at a temperature of 23 ° C at a strain rate of 4 × 10 -7 inches / sec. A constant velocity tensile test was carried out. In the present invention, the breaking stress is 500 MPa or more, which is excellent in stress corrosion cracking resistance (within the scope of the present invention). Further preferably, the breaking stress is 600 MPa or more.
將根據以上而獲得之結果表示於表3中。 The results obtained based on the above are shown in Table 3.
確認本發明例滿足所述目標性能(母材的降伏強度為400MPa以上、低溫韌性是吸收能量(vE-196)的平均值為50J以上、耐應力腐蝕破裂性是破斷應力為500MPa以上)。另一方面,超出本發明的範圍的比較例的母材強度、低溫韌性、及耐應力腐蝕破裂性的任意一個以上無法滿足所述目標性能。再者,在表3中,作為比較例的鋼板No.12雖然成分組成中的C超出本發明的範圍而造成穩定的沃斯田體少,但不穩定的沃斯田體多,因此平均圓等效直徑為10μm以上且長徑與短徑的縱橫比為3以上的沃斯田體的面積率為70%。 It was confirmed that the example of the present invention satisfies the target performance (the falling strength of the base material is 400 MPa or more, the low temperature toughness is the average value of the absorbed energy (vE - 196 ) is 50 J or more, and the stress corrosion cracking resistance is the breaking stress of 500 MPa or more). On the other hand, any one or more of the base material strength, the low temperature toughness, and the stress corrosion cracking resistance of the comparative example beyond the scope of the present invention cannot satisfy the target performance. In addition, in the steel plate No. 12 of the comparative example, although the C in the component composition is outside the range of the present invention, the stable Worth is small, but the unstable Worth is large, so the average circle is The area ratio of the Worth field having an equivalent diameter of 10 μm or more and an aspect ratio of the long diameter to the short diameter of 3 or more is 70%.
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CN109518098A (en) * | 2018-10-29 | 2019-03-26 | 南京钢铁股份有限公司 | A kind of austenitic cryogenic steel and preparation method thereof |
CN111663080B (en) * | 2020-06-23 | 2021-11-12 | 中南大学 | Manufacturing method of fine-grain low-carbon high-strength steel thin strip |
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CN102822371A (en) * | 2010-03-30 | 2012-12-12 | 杰富意钢铁株式会社 | Steel sheet with high tensile strength and superior ductility and method for producing same |
TW201323625A (en) * | 2011-09-16 | 2013-06-16 | Jfe Steel Corp | High-strength steel sheet having excellent workability and method for manufacturing the same |
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CN101107377A (en) * | 2005-01-21 | 2008-01-16 | 阿塞洛法国公司 | Method for producing austenitic iron-carbon-manganese metal sheets, and sheets produced thereby |
CN102822371A (en) * | 2010-03-30 | 2012-12-12 | 杰富意钢铁株式会社 | Steel sheet with high tensile strength and superior ductility and method for producing same |
TW201323625A (en) * | 2011-09-16 | 2013-06-16 | Jfe Steel Corp | High-strength steel sheet having excellent workability and method for manufacturing the same |
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