KR101242807B1 - Low alloy hot-rolled steel sheet having excellent corrosion resistance and method for manufacturing the same - Google Patents
Low alloy hot-rolled steel sheet having excellent corrosion resistance and method for manufacturing the same Download PDFInfo
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- KR101242807B1 KR101242807B1 KR1020100094430A KR20100094430A KR101242807B1 KR 101242807 B1 KR101242807 B1 KR 101242807B1 KR 1020100094430 A KR1020100094430 A KR 1020100094430A KR 20100094430 A KR20100094430 A KR 20100094430A KR 101242807 B1 KR101242807 B1 KR 101242807B1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
Abstract
본 발명은 화력 발전소 탈황, 탈질설비, 예열기 및 이들의 부품 또는 보일러 배관 및 주변부품 등의 소재로 사용되는 황산 및 황산-염산 복합 내식성이 우수한 열연강판에 관한 것으로서, 중량%로, C:0.04~0.15%, Si: 0.4~1.0%, Mn: 0.7~1.3, S: 0.02%이하, P: 0.02%이하, Al: 0.01~0.1%, W: 0.08~0.15%, 나머지는 Fe 및 불가피한 불순물을 포함하고, 상기 W와 C는 ((W/183)-(C/12)/15)*183의 값이 0 이상을 만족하는 내식성이 우수한 저합금 열연강판 및 이를 제조하는 방법을 제공한다.The present invention relates to a hot rolled steel sheet excellent in sulfuric acid and sulfuric acid-hydrochloric acid composite corrosion resistance used as a material for desulfurization of a thermal power plant, denitrification equipment, preheater and parts thereof, boiler piping and peripheral parts, etc. 0.15%, Si: 0.4-1.0%, Mn: 0.7-1.3, S: 0.02% or less, P: 0.02% or less, Al: 0.01-0.1%, W: 0.08-0.15%, the rest contains Fe and unavoidable impurities And, W and C provides a low-alloy hot-rolled steel sheet excellent in corrosion resistance that satisfies the value of ((W / 183)-(C / 12) / 15) * 183 or more and a method of manufacturing the same.
Description
본 발명은 내식성이 우수한 열연강판에 관한 것으로, 보다 상세하게는 화력 발전소 탈황, 탈질설비, 예열기 및 이들의 부품 또는 보일러 배관 및 주변부품 등의 소재로 사용되는 황산 및 황산-염산 복합 내식성이 우수한 저합금 열연강판 및 그 제조방법에 관한 것이다.The present invention relates to a hot-rolled steel sheet having excellent corrosion resistance, and more particularly, sulfuric acid and sulfuric acid-hydrochloric acid composite corrosion resistance used in materials such as thermal power plant desulfurization, denitrification equipment, preheater and parts thereof, boiler piping and peripheral parts. An alloy hot rolled steel sheet and a method of manufacturing the same.
황산 또는 황산-염산 복합 내식강은 석탄 또는 석유 등 화석 연료를 연소하면서 생성되는 아황산가스 및 염소가스가 함유된 배기가스가 수분과 반응을 하여 황산 및 염산을 생성하여 황산 또는 황산-염산 복합 부식이 심각한 화력발전소 탈황 및 탈질설비 또는 복합 발전소의 배관 및 GGH(Gas Gas Heater)의 비교적 두꺼운 두께의 강판을 사용해야 하는 열소자(heat element)소재 등으로 이용된다.
Sulfuric acid or sulfuric acid-hydrochloric acid corrosion resistant steels produce sulfuric acid and hydrochloric acid by producing sulfuric acid and hydrochloric acid by the reaction of sulfur dioxide and chlorine gas exhaust gas generated by burning fossil fuels such as coal or petroleum with water. It is used as a desulfurization and denitrification facility for a serious thermal power plant, or as a heat element material that requires the use of a relatively thick thickness steel plate of a gas gas heater (GGH).
일반적으로 황산-염산 복합 내식강은 황산 및 염산분위기에서 일반강 보다 부식속도를 지연시키기 위하여 강중에 Cu를 다량 첨가하는 것으로 알려져 왔다. Cu는 다른 첨가 원소에 비해 황산 부식속도를 크게 지연시키는 효과가 월등하지만 많이 첨가할 경우 열간압연시 크랙발생등의 이유로 Cu를 적당량 첨가하고 다른 원소를 복합 첨가하는 강(일본 특개평9-25536호, 특개평10-110237호, 한국공개특허 제2007-0138183호 등)이 개발되었다.
In general, sulfuric acid-hydrochloric acid corrosion resistant steel has been known to add a large amount of Cu in the steel in order to delay the corrosion rate than the general steel in sulfuric acid and hydrochloric acid atmosphere. Cu has a much better effect of delaying the corrosion rate of sulfuric acid than other additives, but if it is added a large amount, steel added by adding an appropriate amount of Cu and combining other elements for reasons of cracking during hot rolling (Japanese Patent Laid-Open No. 9-25536) , Japanese Patent Application Laid-Open No. 10-110237, Korean Patent Publication No. 2007-0138183, and the like.
그러나, 상기 Cu첨가강은 비교적 낮은 융점을 가지는 Cu이 편석되거나 농도가 높은 부위에서는 약간의 변형에 의해서도 크랙이 발생하기 쉽다. 따라서 연속 주조 과정에서 가공을 많이 받는 슬라브의 코너 등에 크랙이 발생하여 열간압연후에는 표면결함으로 잔존하여 다른 부위보다 먼저 부식하는 문제점이 있다.
However, in the Cu-added steel, cracks are liable to occur even by slight deformation in areas where Cu having a relatively low melting point segregates or has a high concentration. Therefore, cracks are generated in corners of slabs which are subjected to a lot of processing in the continuous casting process, and thus, after hot rolling, they remain as surface defects and rust before other parts.
상기 Cu첨가강이 갖는 문제점을 해결하기 위해 Ni를 첨가하지만 근본적인 해결책이 되지는 못할 뿐만 아니라 Ni는 고가의 합금원소로 제조원가를 크게 상승시키는 문제가 있다.
Although Ni is added to solve the problem of the Cu-added steel, it is not a fundamental solution, and Ni has a problem of significantly increasing the manufacturing cost with expensive alloy elements.
실제 현장에서는 부식환경이 매우 심각한 부분에는 높은 황산 내식강이 필요하지만 탈황 및 탈질설비를 통과한 배연가스는 부식 분위기가 많이 완화되어 있어, 이 부위에는 굳이 값비싼 고내식 강판을 사용할 필요가 없다. 그렇지만 이 부위에 일반강을 사용할 경우에는 심각하지는 않지만 황산 또는 황산-염산 복합 부식분위기이므로 수명이 너무 짧아 교환주기가 빨라지는 문제점이 있다.
In the actual field, high sulfuric acid corrosion resistant steel is needed in the very severe corrosion environment, but the flue gas passed through the desulfurization and denitrification system has a lot of corrosive atmosphere, so there is no need to use expensive high corrosion resistant steel sheet. However, the use of ordinary steel in this area is not serious, but sulfuric acid or sulfuric acid-hydrochloric acid complex corrosion atmosphere has a problem that the life cycle is too short, so the exchange cycle is faster.
본 발명의 일측면은 일반강에 비해 내식성이 월등히 우수하고, Cu를 첨가한 고내식강에 비해 합금원소 첨가량을 낮춰 제조원가를 절감시킬 수 있는 열연강판 및 그 제조방법을 제공하고자 하는 것이다.One aspect of the present invention is to provide a hot-rolled steel sheet and a method for manufacturing the same, which are excellent in corrosion resistance compared to general steel, and can reduce the production cost by lowering the alloying element added amount compared to high corrosion-resistant steel with Cu.
본 발명은 중량%로, C:0.04~0.15%, Si: 0.4~1.0%, Mn: 0.7~1.3, S: 0.02%이하, P: 0.02%이하, Al: 0.01~0.1%, W: 0.08~0.15%, 나머지는 Fe 및 불가피한 불순물을 포함하고, 상기 W와 C는 ((W/183)-(C/12)/15)*183의 값이 0 이상을 만족하는 내식성이 우수한 저합금 열연강판을 제공한다.
In the present invention, by weight%, C: 0.04 to 0.15%, Si: 0.4 to 1.0%, Mn: 0.7 to 1.3, S: 0.02% or less, P: 0.02% or less, Al: 0.01 to 0.1%, W: 0.08 to 0.15%, the rest contains Fe and unavoidable impurities, and W and C are low alloy hot rolled steel sheets having excellent corrosion resistance such that the value of ((W / 183)-(C / 12) / 15) * 183 satisfies 0 or more. To provide.
또한, 본 발명은 상기 조성을 만족하는 만족하는 강 슬라브를 1200℃ 이상의 온도로 가열하는 단계;In addition, the present invention comprises the steps of heating a satisfactory steel slab satisfying the composition to a temperature of 1200 ℃ or more;
상기 가열된 슬라브를 열간압연하고, 880℃ 이하에서 마무리 압연하는 단계; 및Hot rolling the heated slab and finishing rolling at 880 ° C. or less; And
상기 압연 후 650℃이하에서 권취하는 단계를 포함하는 내식성이 우수한 저합금 열연강판의 제조방법을 제공한다.It provides a method for producing a low-alloy hot rolled steel sheet excellent in corrosion resistance including the step of winding at 650 ℃ or less after the rolling.
본 발명의 열연강판은 황산 내식성 뿐만 아니라, 황산-염산 복합 내식성이 우수하여, 황산 노점 부식 또는 황산-염산 복합 부식이 발생하는 발전소 예열기 등의 비교적 두께를 요구하는 소재 및 탈질, 탈황설비, 보일러 배관 및 주변 장치 소재의 수명을 크게 연장하는 효과가 있고, 저합금을 통해 비용을 크게 줄일 수 있는 효과가 있다.Hot rolled steel sheet of the present invention not only sulfuric acid corrosion resistance, but also excellent sulfuric acid-hydrochloric acid corrosion resistance, materials requiring relatively thick, such as sulfuric acid dew point corrosion or sulfuric acid-hydrochloric acid composite corrosion, denitrification, desulfurization equipment, boiler piping And it has the effect of greatly extending the life of the peripheral material material, there is an effect that can significantly reduce the cost through low alloy.
이하, 본 발명에 대하여 상세히 설명한다.Hereinafter, the present invention will be described in detail.
본 발명자들은 강판의 조성에 텅스텐(W)를 첨가하고 W 첨가량과 C의 함량을 제어함으로써, 텅스텐 산화물을 이용하여 황산 또는 황산-염산에 대한 내식성을 개선할 수 있음을 인지하고 본 발명에 이르게 되었다.
The inventors have realized that by adding tungsten (W) to the composition of the steel sheet and controlling the amount of W added and the content of C, the corrosion resistance to sulfuric acid or sulfuric acid-hydrochloric acid can be improved by using tungsten oxide. .
이하, 본 발명 열연강판의 조성범위에 대하여 상세히 설명한다(중량%).Hereinafter, the composition range of the hot-rolled steel sheet of the present invention will be described in detail (% by weight).
탄소(C): 0.04~0.15%Carbon (C): 0.04-0.15%
C는 강판의 강도를 확보하기 위해 첨가하는 원소로, 그 함량이 0.04% 미만에서는 내황산강 용도의 열연강판으로 사용하기에 강도가 너무 낮은 문제가 있으며, 0.15%를 초과하게 되면 W 첨가강의 내식성을 크게 저하시키는 W 탄화물의 생성량이 많아져 내식성을 크게 저하시키므로, 그 상한을 0.15%로 하는 것이 바람직하다.
C is an element added to secure the strength of the steel sheet, when the content is less than 0.04%, there is a problem that the strength is too low to be used as a hot-rolled steel sheet for sulfuric acid resistant steel, and when it exceeds 0.15%, the corrosion resistance of W-added steel Since the amount of generation of W carbide which greatly decreases the amount greatly increases the corrosion resistance, the upper limit thereof is preferably 0.15%.
실리콘(Si):0.4~1.0%Silicon (Si): 0.4-1.0%
Si는 C와 마찬가지로, 강도를 향상하기 위한 원소로 0.4% 미만이면 강도가 너무 낮아져 열연강판으로 사용하기에 적합하지 않아, 0.4% 이상 첨가하는 것이 바람직하며, 그 함량이 1.0%를 초과하는 경우에는 실리콘 산화물 생성에 의한 표면 결함 발생율이 높으므로 그 상한을 1.0%로 하는 것이 바람직하다.
Like C, Si is an element for improving strength, and if it is less than 0.4%, the strength is too low to be suitable for use as a hot rolled steel sheet. Therefore, it is preferable to add at least 0.4%, and if the content exceeds 1.0%, Since the surface defect generation rate by silicon oxide production | generation is high, it is preferable to set the upper limit to 1.0%.
망간(Mn): 0.7~1.3%Manganese (Mn): 0.7-1.3%
Mn은 강중 고용 황을 망간황화물로 석출하여 고용 황에 의한 적열취성(Hot shortness)을 방지하는 역할을 한다. 본 발명에서는 상기 적열취성 방지 및 고용강화를 위해 Mn이 첨가된다. 상기 Mn의 함량이 0.7% 미만에서는 강도가 너무 낮아 열연강판으로 사용하기 곤란하고, 1.3%를 초과하는 경우에는 Mn의 증가량에 비해 강도 증가율이 낮아 첨가효율이 매우 낮아져 상한을 1.3%로 하는 것이 바람직하다.
Mn precipitates solid sulfur in steel as manganese sulfide to prevent hot shortness caused by solid sulfur. In the present invention, Mn is added for preventing the red brittleness and strengthening the solid solution. When the Mn content is less than 0.7%, the strength is too low to be used as a hot rolled steel sheet. When the Mn content is more than 1.3%, the increase in strength is low compared to the increase amount of Mn, so the addition efficiency is very low, so the upper limit is preferably 1.3%. Do.
인(P): 0.02%이하(0은 제외)Phosphorus (P): 0.02% or less (excluding 0)
P의 함량이 0.02%이상 함유할 경우 황산-염산 복합 내식성이 크게 저하되므로, 그 상한을 0.02%로 하는 것이 바람직하다.
If the content of P is 0.02% or more, sulfuric acid-hydrochloric acid composite corrosion resistance is greatly lowered, so the upper limit is preferably 0.02%.
황(S): 0.02%이하(0은 제외)Sulfur (S): 0.02% or less (excluding 0)
S는 가능한 낮게 첨가하는 것이 바람직하며, 0.02%를 첨가하는 경우에는 열간취성에 의한 결함발생 가능성이 높기 때문에 그 상한을 0.02%로 하는 것이 바람직하다.
It is preferable to add S as low as possible, and when it adds 0.02%, since the possibility of the defect by hot brittleness is high, it is preferable to make the upper limit into 0.02%.
알루미늄(Al): 0.01~0.1%Aluminum (Al): 0.01 ~ 0.1%
Al은 통상 탈산제 역할을 하는데 Al-killed강 제조시 첨가되는 0.01%를 하한으로 하고, 0.1%를 초과하게 되면 표면 결함 발생 확률이 높고 연신율이 저하되므로, 그 상한을 0.1%로 하는 것이 바람직하다.
Al usually acts as a deoxidizer, and the lower limit is 0.01% added during the production of Al-killed steel, and when it exceeds 0.1%, the probability of surface defects is high and the elongation is lowered. Therefore, the upper limit is preferably 0.1%.
텅스텐(W): 0.08~0.15%Tungsten (W): 0.08-0.15%
W은 황산 내식성 및 황산-염산 복합 내식성을 향상시키는 역할을 하며, 이를 위해서 0.08% 이상 첨가해야 황산 또는 황산-염산 분위기에 일정량 이상의 텅스텐 산화물의 생성으로 일반강과 비교하여 2배이상의 내식성을 가질 수 있다. 따라서, W 첨가량이 증가할수록 내식성은 증가하나, 0.15%를 초과하여 첨가량을 증가할수록 텅스텐 탄화물의 생성량이 증가하여 실제 내식성 향상에 주도적인 역할을 하는 텅스텐 산화물의 증가율은 높지 않아 내식성 증가율이 낮아져 첨가량 증가에 따른 첨가 효율이 크게 떨어지게 된다. 이를 위해 그 상한을 0.15%로 하는 것이 바람직하다.
W serves to improve sulfuric acid corrosion resistance and sulfuric acid-hydrochloric acid composite corrosion resistance. For this purpose, at least 0.08% may be added to produce sulfuric acid or a certain amount of tungsten oxide in sulfuric acid-hydrochloric acid atmosphere so that the corrosion resistance can be more than twice that of general steel. . Therefore, as the amount of W added increases, the corrosion resistance increases, but as the amount added exceeds 0.15%, the production of tungsten carbide increases and the increase rate of tungsten oxide, which plays a leading role in improving the corrosion resistance, is not high. The addition efficiency is greatly reduced. For this purpose, the upper limit is preferably made 0.15%.
상기 조성 이외에 나머지는 Fe 및 불가피한 불순물로 이루어진다. 다만, 상기 조성이외에 다른 조성이 포함될 수 없음을 배제하는 것은 아니다.
In addition to the above composition, the remainder consists of Fe and unavoidable impurities. However, it is not to be excluded that no other composition can be included in addition to the above composition.
상기 조성에 있어서, W과 C는 ((W/183)-(C/12)/15)*183≥0을 만족하는 것이 바람직하다. 상기 관계식은 본 발명에서 가장 중요한 내식성 향상 인자인 텅스텐 산화물을 일정량 이상 확보하기 위한 것으로, 그 값이 0 미만이면 텅스텐 산화물의 양이 너무 적어 내식성이 크게 저하되므로, 그 값이 0이상인 것이 바람직하다.
In the above composition, W and C preferably satisfy ((W / 183)-(C / 12) / 15) * 183 ≧ 0. The above relational formula is for securing a certain amount or more of tungsten oxide, which is the most important corrosion resistance improving factor in the present invention. If the value is less than 0, the amount of tungsten oxide is too small and the corrosion resistance is greatly reduced, so the value is preferably 0 or more.
이하, 본 발명의 제조방법에 대하여 상세히 설명한다.Hereinafter, the production method of the present invention will be described in detail.
상기 조성을 만족하는 강 슬라브를 1200℃ 이상의 온도로 가열한다. 1200℃ 이상에서 가열하는 이유는 슬라브 상태에서 석출한 텅스텐 탄화물을 완전히 재용해시키기 위한 것으로 그 온도가 1200℃ 미만에서는 용해되지 않은 텅스텐 탄화물이 남아있어 황산 또는 황산-염산 복합 분위기에서 고용 텅스텐의 산화로 생성되는 텅스텐 산화물의 양이 적어져 내식 효과가 낮아진다. 상기 가열온도의 상한을 특별히 한정하지 않으나, 공정의 경제성을 고려하면, 1300℃이하로 하는 것이 바람직하다.
A steel slab satisfying the above composition is heated to a temperature of at least 1200 ° C. The reason for heating above 1200 ℃ is to completely re-dissolve the tungsten carbide precipitated in the slab state. If the temperature is below 1200 ℃, the undissolved tungsten carbide remains, so that the oxidation of solid solution tungsten in sulfuric acid or sulfuric acid-hydrochloric acid complex atmosphere The amount of tungsten oxide produced is lowered, which lowers the effect of corrosion. Although the upper limit of the said heating temperature is not specifically limited, Considering the economical process, it is preferable to set it as 1300 degrees C or less.
상기 가열된 슬라브를 열간압연하고, 마무리 압연온도는 880℃ 이하에서 행하는 것이 바람직하다. 상기 마무리 압연온도가 높으면 텅스텐 탄화물의 생성량이 많아지지만, 마무리 압연온도가 880℃이하에서는 석출되는 텅스텐 탄화물의 양이 급격히 줄어들어 내식성을 향상시키기 때문에 그 온도를 880℃이하로 하는 것이 바람직하다. 압연성을 고려하면 하한은 800℃로 행하는 것이 바람직하다.
The heated slab is hot rolled, and the finish rolling temperature is preferably performed at 880 ° C. or lower. When the finish rolling temperature is high, the amount of tungsten carbide produced increases, but since the amount of tungsten carbide precipitated decreases rapidly at 880 ° C. or lower to improve corrosion resistance, the temperature is preferably 880 ° C. or lower. In consideration of rolling property, the lower limit is preferably performed at 800 ° C.
상기 압연 후 권취를 행한다. 이때 권취온도는 650℃이하에서 행하는 것이 바람직하다. 권취온도가 낮을수록 내식성을 저하하는 텅스텐 탄화물 생성량이 적어지기 때문에 가능한 낮은 온도에서 권취를 행하는 것이 바람직하다. 상기 650℃이하에서 상기 텅스텐 탄화물 생성량이 급격히 줄어들어 권취온도의 상한을 650℃로 하는 것이 바람직하다. 한편 상기 권취는 500℃ 미만에서 행하는 경우 연성이 크게 저하하므로 그 하한을 500℃로 하는 것이 바람직하다.
Winding is performed after the said rolling. At this time, it is preferable to perform coiling temperature below 650 degreeC. Since the lower the coiling temperature, the lower the amount of tungsten carbide produced, which lowers the corrosion resistance, it is preferable to wind the coil at the lowest possible temperature. It is preferable that the amount of tungsten carbide production abruptly decreases below 650 ° C, so that the upper limit of the winding temperature is 650 ° C. On the other hand, when said winding is performed at less than 500 degreeC, since ductility falls significantly, it is preferable to make the minimum to 500 degreeC.
본 발명의 열연강판은 텅스텐 산화물로 이루어진 텅스텐 산화 피막을 포함한다. 상기 텅스텐 산화 피막은 표면층에 생성되어 내식성을 향상시킨다. 텅스텐 탄화물이 생성되면 텅스텐 산화물로 생성되는 텅스텐의 양이 그만큼 줄어들어 텅스텐 탄화물에 의해 내식성이 저하하므로 가능한 텅스텐 탄화물의 생성을 억제하여야 한다. 이를 위해, 본 발명에서는 상기 조성식과 열간압연 조건을 제어하여 텅스텐 탄화물의 생성을 억제하고, 내식성이 우수한 텅스텐 산화물을 생성시킨다.
The hot rolled steel sheet of the present invention includes a tungsten oxide film made of tungsten oxide. The tungsten oxide film is formed on the surface layer to improve the corrosion resistance. When tungsten carbide is produced, the amount of tungsten produced by tungsten oxide is reduced by that amount, and the corrosion resistance is degraded by tungsten carbide, so the production of tungsten carbide should be suppressed as much as possible. To this end, in the present invention, the composition formula and hot rolling conditions are controlled to suppress the production of tungsten carbide and produce tungsten oxide having excellent corrosion resistance.
본 발명의 열연강판은 황산 50부피%용액에 대한 부식 감량이 200㎎/㎠/hr 이하이고, 황산 16.9부피% + 염산 0.35부피%용액에 대한 부식 감량이 50㎎/㎠/hr 이하로서 매우 우수한 내식성을 갖는다.
The hot rolled steel sheet of the present invention has excellent corrosion loss of 50 vol% sulfuric acid solution of 200 mg / cm 2 / hr or less, and corrosion loss of 16.9 vol% sulfuric acid + 0.35 vol% hydrochloric acid solution of 50 mg / cm 2 / hr. Has corrosion resistance.
이하, 본 발명의 실시예에 대하여 상세히 설명한다. 다만 하기 실시예에 의하여 본 발명이 한정되는 것은 아니다.Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited by the following examples.
(실시예)(Example)
하기 표 1의 조성을 갖는 강슬라브를 1250℃의 가열로에서 1시간 유지한 후 열간압연을 실시하였다. 이때 열간 마무리 압연온도는 850℃, 권취온도는 600℃로 하여 최종두께 4.5㎜의 발명강을 제조하였다. 표 1에서 관계식은 ((W/183)-(C/12)/15)*183을 의미한다.The steel slab having the composition shown in Table 1 was maintained in a heating furnace at 1250 ° C. for 1 hour, and then hot rolled. At this time, the hot finish rolling temperature was 850 ℃, the winding temperature was 600 ℃ to produce an invention steel of the final thickness 4.5mm. In Table 1, the relation means ((W / 183)-(C / 12) / 15) * 183.
한편, 표 1의 비교강에서는 공정조건에 따른 변화를 관찰하기 위해, 가열온도(SRT), 마무리압연 온도(FT) 및 권취온도(CT)를 달리하여 제조하였다.
On the other hand, in the comparative steel of Table 1, in order to observe the change according to the process conditions, the heating temperature (SRT), the finish rolling temperature (FT) and the winding temperature (CT) were manufactured by different.
상기 발명강과 비교강의 내식성을 알아보기 위해서, 먼저 황산-염산 복합부식조건에서 부식특성을 조사하기 위해 황산 16.9vol.% + 염산 0.35vol.%용액에 60℃에서 6시간 동안 침적하여 각 시편의 부식감량을 측정하였다. 또한 황산분위기에서 내식성을 평가하기 위하여 황산 50vol.%용액에 70℃에서 1시간 침적하여 부식속도를 측정하고 그 결과를 표 2에 나타내었다.In order to investigate the corrosion resistance of the invention steel and comparative steel, first, the corrosion of each specimen by immersing in 16.9 vol.% Sulfuric acid + 0.35 vol. Loss was measured. In addition, in order to evaluate the corrosion resistance in sulfuric acid atmosphere, the corrosion rate was measured by dipping in 50 vol.% Sulfuric acid solution at 70 ° C. for 1 hour, and the results are shown in Table 2.
division
상기 표 2의 결과에서 알 수 있듯이, 본 발명의 범위에 속하는 강은 황산에 대한 부식감량이 200㎎/㎠/hr 이하로 매우 우수한 내황산 부식 특성을 나타내며, 황산-염산 복합 부식감량도 50㎎/㎠/hr 이하로 매우 우수한 내식 특성을 나타낸다. As can be seen from the results of Table 2, the steel belonging to the scope of the present invention exhibits excellent corrosion resistance of sulfuric acid corrosion resistance of sulfuric acid is less than 200mg / ㎠ / hr, sulfuric acid-hydrochloric acid composite corrosion loss 50mg Very good corrosion resistance is shown below / cm 2 / hr.
이를 보다 자세히 살펴보면, 발명강 1 내지 4는 W의 함량이 증가할수록 황산 부식 및 황산-염산 복합 부식에 대한 내식성이 우수한 것을 알 수 있다. W가 0.093중량% 첨가된 발명강 1만 하더라도 일반강보다 내식성이 5배 이상 우수하며, 발명강 4는 황산 부식감량이 121㎎/㎠/hr, 황산-염산 복합 부식감량이 29.3㎎/㎠/hr로 일반강보다 약 8배 이상의 내식성을 갖는다.
Looking at this in more detail, it can be seen that the invention steels 1 to 4 have excellent corrosion resistance against sulfuric acid corrosion and sulfuric acid-hydrochloric acid composite corrosion as the content of W increases. Even if the invention steel 1 added 0.093% by weight of W, the corrosion resistance was 5 times better than that of ordinary steel, and the invention steel 4 had a loss of sulfuric acid corrosion of 121 mg / cm 2 / hr and a sulfuric acid-hydrochloric acid composite corrosion loss of 29.3 mg / cm 2 Its corrosion resistance is about 8 times higher than that of ordinary steel.
이에 비해, 비교강 1은 W이 전혀 첨가되지 않아 황산 부식감량이 1050㎎/㎠/hr, 황산-염산 복합 부식감량이 249㎎/㎠/hr로 발명강보다 5배 이상의 부식속도를 나타내어 내식성이 매우 낮다. 비교강 2는 W 함량이 본 발명에 미치지 못하고, ((W/183)-(C/12)/15)*183의 값도 0 이하로 본 발명 범위에 벗어나 부식속도가 발명강보다 매우 높은 수준이다.
In comparison, Comparative Steel 1 showed no corrosion at all because W was not added at all, and thus the sulfuric acid corrosion loss was 1050 mg / cm 2 / hr, and the sulfuric acid-hydrochloric acid complex corrosion loss was 249 mg / cm 2 / hr. Very low Comparative steel 2 is less than the W content of the present invention, and the value of ((W / 183)-(C / 12) / 15) * 183 is also 0 or less, which is outside the scope of the present invention, and the corrosion rate is much higher than that of the inventive steel. to be.
비교강 3은 C 및 W가 본 발명의 범위에 속하지만, ((W/183)-(C/12)/15)*183의 값이 0 이하로 낮아 내식성이 크게 낮아졌다. In Comparative Steel 3, C and W were within the scope of the present invention, but the value of ((W / 183)-(C / 12) / 15) * 183 was 0 or less, which greatly lowered the corrosion resistance.
비교강 4는 C, W 및 ((W/183)-(C/12)/15)*183의 값이 본 발명 범위에 포함되지만, 열간 압연 조건이 본 발명 범위를 벗어나 본 발명강에 비해 내식성이 낮음을 확인할 수 있다. 이는 열간압연 중 텅스텐 탄화물의 생성으로 황산 또는 황산-염산 복합 분위기 중 내식성을 향상시키는 텅스텐 산화물 생성량이 적기 때문인 것으로 예상할 수 있다.In Comparative Steel 4, the values of C, W and ((W / 183)-(C / 12) / 15) * 183 are included in the scope of the present invention, but the hot rolling conditions are out of the scope of the present invention and are more corrosion resistant than the inventive steel. You can see that this is low. This may be because the production of tungsten carbide during hot rolling is due to the low amount of tungsten oxide to improve the corrosion resistance in sulfuric acid or sulfuric acid-hydrochloric acid complex atmosphere.
Claims (5)
상기 W와 C는 ((W/183)-(C/12)/15)*183의 값이 0 이상을 만족하는 내식성이 우수한 저합금 열연강판.
By weight%, C: 0.04 to 0.15%, Si: 0.4 to 1.0%, Mn: 0.7 to 1.3, S: 0.02% or less, P: 0.02% or less, Al: 0.01 to 0.1%, W: 0.08 to 0.15%, The rest contains Fe and inevitable impurities,
W and C is a low alloy hot rolled steel sheet excellent in corrosion resistance ((W / 183)-(C / 12) / 15) * 183 is equal to or greater than zero.
상기 열연강판은 텅스텐 산화물을 포함하는 내식성이 우수한 저합금 열연강판.
The method according to claim 1,
The hot rolled steel sheet is a low alloy hot rolled steel sheet excellent corrosion resistance containing tungsten oxide.
상기 열연강판은 황산 50부피%용액에 대한 부식 감량이 200㎎/㎠/hr 이하인 내식성이 우수한 저합금 열연강판.
The method according to claim 1,
The hot rolled steel sheet is a low alloy hot rolled steel sheet excellent in corrosion resistance of less than 200mg / ㎠ / hr corrosion loss to 50 vol% sulfuric acid solution.
상기 열연강판은 황산 16.9부피% + 염산 0.35부피%용액에 대한 부식 감량이 50㎎/㎠/hr 이하인 내식성이 우수한 저합금 열연강판.
The method according to claim 1,
The hot rolled steel sheet is a corrosion resistant low alloy hot rolled steel sheet having a corrosion loss of 16.9% by volume of sulfuric acid + 0.35% by volume of hydrochloric acid solution of 50 mg / cm 2 / hr or less.
상기 가열된 슬라브를 열간압연하고, 880℃ 이하에서 마무리 압연하는 단계; 및
상기 압연 후 650℃이하에서 권취하는 단계
를 포함하는 내식성이 우수한 저합금 열연강판의 제조방법.By weight%, C: 0.04 to 0.15%, Si: 0.4 to 1.0%, Mn: 0.7 to 1.3, S: 0.02% or less, P: 0.02% or less, Al: 0.01 to 0.1%, W: 0.08 to 0.15%, The remainder contains Fe and unavoidable impurities, and W and C heat the steel slab having a value of ((W / 183)-(C / 12) / 15) * 183 satisfying 0 or more to a temperature of 1200 ° C. or more. step;
Hot rolling the heated slab and finishing rolling at 880 ° C. or less; And
Winding step below 650 ℃ after the rolling
Method for producing a low alloy hot rolled steel sheet excellent corrosion resistance comprising a.
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| KR100928774B1 (en) | 2007-12-27 | 2009-11-25 | 주식회사 포스코 | Sulfuric acid and hydrochloric acid corrosion resistant steel with excellent sulfuric acid and hydrochloric acid corrosion resistance |
| KR20100023047A (en) * | 2007-07-27 | 2010-03-03 | 제이에프이 스틸 가부시키가이샤 | Hot-rolled shape steel for ships and process for manufacturing the same |
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| KR20100023047A (en) * | 2007-07-27 | 2010-03-03 | 제이에프이 스틸 가부시키가이샤 | Hot-rolled shape steel for ships and process for manufacturing the same |
| KR100928774B1 (en) | 2007-12-27 | 2009-11-25 | 주식회사 포스코 | Sulfuric acid and hydrochloric acid corrosion resistant steel with excellent sulfuric acid and hydrochloric acid corrosion resistance |
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