JP2009046716A - Gas-exhausting facility manufactured by using structure material which is suitable for diesel engine exhaust system of marine vehicle, and has heat resistance and high corrosion resistance - Google Patents
Gas-exhausting facility manufactured by using structure material which is suitable for diesel engine exhaust system of marine vehicle, and has heat resistance and high corrosion resistance Download PDFInfo
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本発明は、重油、軽油、灯油またはそれらの混合油を燃料とする船舶などに用いられるディーゼルエンジンの排ガス脱硝設備において、排気筒などエンジン排気口から排気筒出口までに用いられる全ての部材の材質に特定の高耐食性オーステナイトステンレス鋼またはＮｉ基合金を使用した耐熱性および高耐食性を有する舶用ディーゼルエンジンのガス排気設備に関する。 The present invention relates to materials for all members used from an exhaust port of an engine, such as an exhaust pipe, to an outlet of an exhaust pipe, in exhaust gas denitration equipment for diesel engines used in ships that use heavy oil, light oil, kerosene, or a mixture thereof as fuel. The present invention relates to a gas exhaust system for a marine diesel engine having heat resistance and high corrosion resistance using a specific high corrosion resistance austenitic stainless steel or Ni-base alloy.
環境問題を論じる場合、船舶などに用いられるエンジンには、船舶推進用エンジン、発電機用補機エンジン、焼却炉が含まれるが、前記２つのエンジンからの排ガス量が圧倒的に多い。エンジンとしては、化石燃料、特に多用される硫黄分の多いＡ，Ｃ重油を燃料とするディーゼルエンジンが主流であり、排ガス中のＮＯＸが規制の対象となりはじめており、徐々に規制は強化されつつある。 When discussing environmental issues, engines used in ships and the like include ship propulsion engines, generator auxiliary engines, and incinerators, but the amount of exhaust gas from the two engines is overwhelmingly large. The engine, fossil fuels, sulfur-rich A to be particularly heavy, diesel engine using C heavy fuel oil is the mainstream, NO X in the exhaust gas is started subject to regulation, while gradually restricting the enhanced is there.
ディーゼルエンジンなどの内燃機関の排気ガス中のＮＯｘを低減する手段としては、触媒を使用しアンモニアや尿素で還元する接触分解方式が広く採用されている。例えば、特許文献１には、内燃機関の排気ガス浄化用の触媒装置や化学プラントの触媒装置に用いられる触媒用メタル担体に関する発明で、ハニカム材としてＦｅ‐Ｃｒ‐Ａｌ合金箔を用いており、表面に酸化アルミニウム皮膜を生じさせ、酸化皮膜の成長によって鋼中のＡｌがＡｌ2Ｏ3として消費し、ＣｒとＦｅの酸化を抑制する原理である。しかしながら、重油、軽油、灯油またはそれらの混合油を燃料とする船舶用ディーゼルエンジンの排気ガス脱硝装置の触媒を対象に考えた場合、エンジン回転数が低下したり、停止するに伴い、排気ガス圧力も低下し燃焼ガス中に含まれる強酸性の物質が逆流したり、停止後の温度低下により生じる結露水に強酸性の物質が溶解するなど、自動車用ディーゼルエンジンや化学プラントの排気ガスと比べ、ガス排気設備全体が極端な腐食環境にさらされる。このため、従来のＦｅ−Ｃｒ−Ａｌ合金箔を用いているメタルハニカム触媒担持体を当該用途に使用すると、ハニカム担持体が腐食し、触媒装置そのものが機能を果たさなくなる危険性があり、これと同様に、触媒担持体を収納する缶体およびその後方に位置する排気筒だけでなく、エンジン回転数の低下や停止時には排気ガスの逆流が生じるので、エンジン排気口から排気筒出口までの全ての部材においても機能を果たさなくなる危険性があった。 As a means for reducing NOx in exhaust gas of an internal combustion engine such as a diesel engine, a catalytic cracking method using a catalyst and reducing with ammonia or urea is widely adopted. For example, Patent Document 1 is an invention relating to a catalyst metal carrier used in a catalyst device for exhaust gas purification of an internal combustion engine or a catalyst device in a chemical plant, and uses an Fe-Cr-Al alloy foil as a honeycomb material. This is the principle that an aluminum oxide film is formed on the surface and Al in the steel is consumed as Al 2 O 3 by the growth of the oxide film and suppresses the oxidation of Cr and Fe. However, when considering the catalyst of exhaust gas denitration equipment for marine diesel engines fueled with heavy oil, light oil, kerosene or a mixture of these, the exhaust gas pressure decreases as the engine speed decreases or stops. Compared with the exhaust gas of automobile diesel engines and chemical plants, such as the strongly acidic substances contained in the combustion gas flow backwards or the strongly acidic substances dissolve in the dew condensation water caused by the temperature drop after the shutdown. The entire gas exhaust system is exposed to an extreme corrosive environment. For this reason, if a metal honeycomb catalyst carrier using a conventional Fe-Cr-Al alloy foil is used for the application, there is a risk that the honeycomb carrier will corrode and the catalytic device itself will not function. Similarly, not only the can body for storing the catalyst carrier and the exhaust pipe located behind the can body, but also exhaust gas backflow occurs when the engine speed is reduced or stopped, so that There was a risk that the member could not perform its function.
すなわち、船舶用ディーゼルエンジンは、重油、軽油、灯油またはそれらの混合油を燃料として用いることが多く、これらは比較的多く硫黄分を含んでおり、排ガス脱硝装置における還元剤として尿素やアンモニアを用いる場合、その脱硝装置は、極端な腐食環境にさらされ、金属である地金の露出した部分を起点に腐食を引き起こし、脱硝装置等を損傷させてしまう。
本発明は、このような問題を解決し、耐熱性に優れ、かつ極端な腐食環境にも耐え得る船舶用ディーゼルエンジン排気ガス用脱硝触媒装置用缶体および排気筒などエンジン排気口から排気筒出口までの全ての部材に適した構成材料及び該構成材料で構成した船舶用ディーゼルエンジンのガス排気設備を提供することを課題とする。 The present invention solves such a problem, has excellent heat resistance, and can withstand an extreme corrosive environment. A canister for a denitration catalyst device for a diesel engine exhaust gas for a marine vessel and an exhaust tube from an engine exhaust port such as an exhaust tube. It is an object of the present invention to provide a constituent material suitable for all the members described above and a gas exhaust equipment for a marine diesel engine made of the constituent material.
上記の課題を解決するため、舶用ディーゼルエンジンの排ガス脱硝装置の缶体および排気筒などエンジン排気口から排気筒出口までの全ての部材が極端な腐食環境下においても耐久性を確保できる手段として、発明者らは、種々試行を重ねた結果、以下の結論を得た。 In order to solve the above problems, as a means for ensuring durability even in an extremely corrosive environment, all members from the engine exhaust port to the exhaust tube outlet, such as the can body and exhaust tube of the exhaust gas denitration device of a marine diesel engine, The inventors have obtained the following conclusions as a result of various trials.
舶用ディーゼルエンジンの排ガス脱硝装置の缶体および排気筒などエンジン排気口から排気筒出口までの全ての部材において、耐熱性および高耐食性を有する特定の構成材料とすることで、極端な腐食環境下においても優れた耐久性を確保することができることが分かった。 In the extreme corrosive environment, all components from the engine exhaust port to the exhaust tube outlet, such as cans and exhaust tubes of marine diesel engine exhaust gas denitration devices, have heat resistance and high corrosion resistance. It was also found that excellent durability can be secured.
この特定の構成材料は、高耐食性かつ高耐熱性を有するオーステナイト系ステンレス鋼またはＮｉ基合金であり、舶用ディーゼルエンジンの排ガス脱硝装置の缶体および排気筒などエンジン排気口から排気筒出口までの全ての部材に用いる。この部位では、エンジンの始動、停止、回転の高低によって脱硝装置内は、１５０℃以上、５５０℃以下の繰り返し熱サイクルに曝されると共に、エンジン停止時には、内部の温度が急激に低下し滞留する排気ガス中の水分が結露すると共に強酸性の硫化物が溶解し、触媒装置内に滞留してしまうので、その結果、金属製部材を腐食させ、致命的損傷を受ける可能性がある。 This specific constituent material is austenitic stainless steel or Ni-based alloy having high corrosion resistance and high heat resistance, and everything from the engine exhaust port to the exhaust tube outlet such as the can body and exhaust tube of the exhaust gas denitration device of marine diesel engines Used for members. In this part, the inside of the denitration device is exposed to repeated heat cycles of 150 ° C. or more and 550 ° C. or less due to the start, stop, and rotation of the engine, and when the engine is stopped, the internal temperature rapidly decreases and stays. Moisture in the exhaust gas condenses and the strongly acidic sulfide dissolves and stays in the catalyst device. As a result, the metal member may be corroded and fatally damaged.
陸上の自動車用ディーゼルエンジンにおいても、触媒を用いた脱硝装置の装着が進められているが、使用する燃料としては硫黄分がＡ，Ｃ重油に比べ非常に少ない軽油が主体となっており、比較的軽微な腐食環境であることから、大問題になることは無かった。 On-shore automobile diesel engines are also being equipped with denitration equipment using catalysts, but the fuel used is mainly diesel oil, which has a much lower sulfur content than A and C heavy oils. Because of its mild and corrosive environment, there was no major problem.
これに対し、船舶用内燃機関においては、海洋上においては海塩粒子や海水が、機関内の給排気装置に浸入することが多く、陸用の内燃機関と比べさらに過酷な環境下で使用され、これらを構成する部品は腐食の危険にさらされ、その上、交換の機会も少ない。かつ使用される燃料は、硫黄分の多いＡ、Ｃ重油が多用される環境において、実際に適用した例のない船舶用脱硝装置を将来設置し使用した場合、還元剤として用いる尿素やアンモニアのリーク分を無害化するために、後段に酸化触媒を設置する必要があるが、同時に排気ガス中にある二酸化硫黄も酸化されて硫酸ガスとなり、排気ガス温度低下に伴う結露と共に、強酸性の硫酸に変化してしまう。 On the other hand, in marine internal combustion engines, sea salt particles and seawater often intrude into the air supply / exhaust system in the marine environment, and are used in harsher environments compared to land internal combustion engines. These components are at risk of corrosion and, in addition, there are few opportunities for replacement. In addition, in the environment where heavy A and C heavy oils containing a large amount of sulfur are used, when a ship-use denitration system that has not been applied in the future is installed and used in the future, leakage of urea or ammonia used as a reducing agent In order to make the components harmless, it is necessary to install an oxidation catalyst in the latter stage, but at the same time, sulfur dioxide in the exhaust gas is oxidized to sulfuric acid gas. It will change.
そこで、発明者らは、これらの問題を解消するために、ガス排気設備の改善を試みた。その結果、舶用ディーゼルエンジンの排ガス脱硝設備の缶体および排気筒などエンジン排気口から排気筒出口までの全ての部材において、耐熱性および高耐食性を有する特定組成の構成材料とすることで、極端な腐食環境下においても優れた耐久性を有することを特徴とする耐熱性および高耐食性を有する船舶用脱硝装置等エンジン排気口から排気筒出口までの全ての部材を開発した。 Therefore, the inventors have tried to improve the gas exhaust equipment in order to solve these problems. As a result, in all the members from the engine exhaust port to the exhaust tube outlet, such as the can body and exhaust tube of the exhaust gas denitration equipment for marine diesel engines, by making the constituent material of a specific composition having heat resistance and high corrosion resistance, We have developed all members from the engine exhaust port to the exhaust tube outlet, such as marine denitration equipment with heat resistance and high corrosion resistance, characterized by having excellent durability even in corrosive environments.
本発明でいうガス排気設備とは、ディーゼルエンジン排気口から排気筒出口までの間にあって、排気ガスと直接接触するすべての部材をいう。具体的には、図１に示される、過給器、尿素などの還元剤注入手段、脱硝器、酸化器、熱交換器、排気筒、および排ガス流路中に設けされる各種センサーなどが例示されるが、これに限定されるものではない。 The gas exhaust facility as used in the present invention refers to all members that are between the diesel engine exhaust port and the exhaust tube outlet and are in direct contact with the exhaust gas. Specifically, the supercharger, the reducing agent injection means such as urea, the denitrator, the oxidizer, the heat exchanger, the exhaust pipe, and various sensors provided in the exhaust gas flow path shown in FIG. 1 are exemplified. However, the present invention is not limited to this.
先ず、構成部材は、１５０℃以上、５５０℃以下の繰り返し熱サイクルが作用しても優れた耐久性を有するよう改善した。主な改善点は、船舶用脱硝装置等を構成する部材を高耐食性、特に、表面発銹の無いステンレス素材を適用した点にある。耐熱性、高耐食性ステンレス鋼と言っても多種多様で、フェライト系ステンレス鋼とＳＵＳ３０４に代表されるオーステナイト系ステンレス鋼が挙げられる。特に前者に挙げたフェライト系ステンレス鋼は、鋼種によっては、ニッケル超合金を凌ぐ耐熱性を有する材料もあるが、発銹する危険性がある。 First, the structural member was improved to have excellent durability even when repeated heat cycles of 150 ° C. or higher and 550 ° C. or lower were applied. The main improvement is that high corrosion resistance, in particular, a stainless steel material having no surface erosion is applied to the members constituting the ship denitration device and the like. There are a wide variety of heat-resistant and high-corrosion-resistant stainless steels, and examples include ferritic stainless steel and austenitic stainless steel represented by SUS304. In particular, the ferritic stainless steels mentioned in the former have a heat resistance that exceeds that of nickel superalloys depending on the type of steel, but there is a risk of starting.
また、上記フェライト系ステンレス鋼やオーステナイト系ステンレス鋼は、一般的に使用されている鋼板と比べ、耐熱性及び耐食性に優れているが、熱膨張率が非常に高いため、設置スペースが限られる船舶内では、図１中に記号を付した箇所、すなわち、排気ダクト、過給器、熱交換器、脱硝装置、排気筒の接続部の少なくとも１箇所に、伸縮吸収機構を設ける必要がある。 In addition, ferritic stainless steel and austenitic stainless steel are superior in heat resistance and corrosion resistance compared to commonly used steel sheets, but ships with limited installation space due to their extremely high coefficient of thermal expansion. Inside, it is necessary to provide an expansion / contraction absorption mechanism at a location indicated by a symbol in FIG. 1, that is, at least one location of an exhaust duct, a supercharger, a heat exchanger, a denitration device, and an exhaust pipe connection.
本発明で使用される伸縮吸収機構は、各部材の接続方向への熱による伸縮を吸収できるものであればいずれのものでも構わないが、例えば図２に示されるものが使用できる。
図２に示したものは、本発明材料の使用用途である舶用ディーゼルエンジン排気口以降から排気筒出口までの一部を構成する熱膨張による歪を緩和するための伸縮吸収機構の一例である。
先ず、図２（ａ）に示した伸縮吸収機構は、各装置間に接続した排気装置使用される材質と同等の金属材料、もしくわ、それ以上の熱伸縮挙動に対して優位な低熱膨張特性と優れた延性持ち合わせた金属材料でできた蛇腹を一体化させ、且つ、変形させることにより、直接的に伸縮を吸収させるしくみである。
次に、図２（ｂ）で示すものは、配管をスライド可能に設置することにより伸縮を吸収する機構になっている。この構造は、スライド部分の隙間からのガス漏れを防止するために、耐熱ゴムや、金属製の薄板等で構成された蛇腹でスライド部全体を覆うようにされていることが好ましい。
The expansion / contraction absorption mechanism used in the present invention may be any one as long as it can absorb expansion and contraction due to heat in the connecting direction of each member. For example, the one shown in FIG. 2 can be used.
What was shown in FIG. 2 is an example of the expansion-contraction absorption mechanism for relieving the distortion | strain by thermal expansion which comprises a part from the marine diesel engine exhaust port after the marine diesel engine exhaust port which is a use application of this invention material.
First, the expansion / contraction absorption mechanism shown in FIG. 2 (a) has a low thermal expansion characteristic superior to a metal material equivalent to the material used for the exhaust device connected between the devices, or more than that. It is a mechanism that directly absorbs expansion and contraction by integrating and deforming a bellows made of a metal material having excellent ductility.
Next, what is shown in FIG. 2B is a mechanism that absorbs expansion and contraction by slidably installing the piping. In order to prevent gas leakage from the gap between the slide portions, this structure is preferably configured so as to cover the entire slide portion with a bellows made of heat-resistant rubber, a thin metal plate, or the like.
すなわち、本発明の実施態様は以下のとおりである。
（１）直接排気ガスと接触する、エンジン排気口から排気筒出口までの部材について、質量％で、Ｎｉ：１４〜６５％、Ｃｒ：１４〜２５％、Ｍｏ：２．５〜２０．０％含有するオーステナイト系ステンレス鋼またはＮｉ基合金により構成されることを特徴とする舶用ディーゼルエンジンのガス排気設備。
（２）高耐食性オーステナイトステンレス鋼またはＮｉ基合金が、質量%で、Ｓｉ：１．０％以下、 Ｍｎ：１．０％以下、Ｃｒ：１４．０〜２５．０％、 Ｎｉ：１４．０〜６５．０％、Ｍｏ：２．５〜２０．０％、Ｎ：０．００１〜０．３０％、Ｃ：０．０３％以下を含有し、残部がＦｅ及び不可避的不純物から成ることを特徴とする（１）記載の舶用ディーゼルエンジンのガス排気設備。
（３）高耐食性オーステナイトステンレス鋼またはＮｉ基合金が、質量％で、Ｓｉ：１．０％以下、Ｍｎ：１．０％以下、Ｃｒ：２０．０〜２５．０％、Ｎｉ：５５．０〜６５．０％、Ｍｏ：８．０〜１０．０％、Ａｌ：０．１〜０．４％、Ｔｉ：０．０４〜０．４％、Ｃ：０．１％以下、および、Ｎｂ％：３．０〜４．２を含有し、残部がＦｅ及び不可避的不純物から成ることを特徴とする（１）記載の舶用ディーゼルエンジンのガス排気設備。
（４）エンジン排気口から排気筒出口までの部材が、排気ダクト、過給器、熱交換器、脱硝装置、排気筒、及びこれら単体もしくはシステムとして制御に用いる計測機器類を含むことを特徴とする（１）ないし（３）の何れかに記載の舶用ディーゼルエンジンのガス排気設備。
（５）排気ダクト、過給器、熱交換器、脱硝装置、排気筒の接続部の少なくとも１箇所に、伸縮吸収機構を設けたことを特徴とする（４）に記載の舶用ディーゼルエンジンのガス排気設備。
That is, the embodiment of the present invention is as follows.
(1) The members from the engine exhaust port to the exhaust tube outlet that are in direct contact with the exhaust gas are in mass%, Ni: 14 to 65%, Cr: 14 to 25%, Mo: 2.5 to 20.0% A gas exhaust system for a marine diesel engine characterized by comprising an austenitic stainless steel or a Ni-base alloy.
(2) High corrosion resistance austenitic stainless steel or Ni-based alloy in mass%, Si: 1.0% or less, Mn: 1.0% or less, Cr: 14.0 to 25.0%, Ni: 14.0 -65.0%, Mo: 2.5-20.0%, N: 0.001-0.30%, C: 0.03% or less, the balance consisting of Fe and inevitable impurities The gas exhaust system for a marine diesel engine as described in (1), which is characterized in that
(3) High corrosion resistance austenitic stainless steel or Ni-based alloy in mass%, Si: 1.0% or less, Mn: 1.0% or less, Cr: 20.0 to 25.0%, Ni: 55.0 -65.0%, Mo: 8.0-10.0%, Al: 0.1-0.4%, Ti: 0.04-0.4%, C: 0.1% or less, and Nb %: A gas exhaust system for a marine diesel engine according to (1), which contains 3.0 to 4.2, and the balance is made of Fe and inevitable impurities.
(4) The member from the engine exhaust port to the exhaust tube outlet includes an exhaust duct, a supercharger, a heat exchanger, a denitration device, an exhaust tube, and measuring instruments used for control as a single unit or a system. The gas exhaust system for a marine diesel engine according to any one of (1) to (3).
(5) Gas for marine diesel engines according to (4), characterized in that an expansion / contraction absorption mechanism is provided in at least one of the exhaust duct, the supercharger, the heat exchanger, the denitration device, and the exhaust pipe connection. Exhaust equipment.
本発明の船舶用脱硝装置の用途である舶用ディーゼルエンジンの排ガス脱硝装置の缶体および排気筒などエンジン排気口から排気筒出口までの全ての部材において必要な性能を発揮させるためには、耐熱性および高耐食性を有する金属材料を適応しなければならず、少なくとも、質量％で、Ｎｉ：１４〜６５％、Ｃｒ：１４〜２５％、Ｍｏ：２．５〜２０．０％を含有するオーステナイト系ステンレス鋼およびＮｉ基合金用いた構成部材とする必要性がある。 In order to exert the required performance in all members from the engine exhaust port to the exhaust tube outlet, such as the can body and exhaust tube of the exhaust gas denitration device of the marine diesel engine which is an application of the ship denitration device of the present invention, And an austenitic system containing at least, by mass, Ni: 14 to 65%, Cr: 14 to 25%, Mo: 2.5 to 20.0%. There is a need for a component using stainless steel and Ni-base alloy.
また、この缶体および排気筒などエンジン排気口から排気筒出口までの全ての部材の金属材質は、質量％で、Ｓｉ：１．０％以下、 Ｍｎ：１．０％以下、Ｃｒ：１４．０〜２５．０％、Ｎｉ：１４．０〜６５．０％、Ｍｏ：２．５〜２０．０％、 Ｎ：０．００１〜０．３％、Ｃ：０．０３％以下を含有し、残部がＦｅ及び不可避的不純物から成る高耐食性オーステナイトステンレス鋼およびＮｉ基合金であっても良い。 Further, the metal materials of all members from the engine exhaust port to the exhaust tube outlet, such as the can body and the exhaust tube, are mass%, Si: 1.0% or less, Mn: 1.0% or less, Cr: 14. 0-25.0%, Ni: 14.0-65.0%, Mo: 2.5-20.0%, N: 0.001-0.3%, C: 0.03% or less Further, the high-corrosion-resistant austenitic stainless steel and Ni-base alloy may be used, the balance being Fe and inevitable impurities.
さらに、質量％で、Ｓｉ：１．０％以下、Ｍｎ：１．０％以下、Ｃｒ：２０．０〜２５．０％、Ｎｉ：５５．０〜６５．０％、Ｍｏ：８．０〜１０．０％、Ｎ：０．００１〜０．３％、Ａｌ：０．１〜０．４％、Ｔｉ：０．０４〜０．４％、Ｃ：０．１％以下、および、Ｎｂ：２．５〜４．１％を含有し、残部がＦｅ及び不可避的不純物から成る高耐食性オーステナイトステンレス鋼およびＦｅ−Ｎｉ合金としても良い。 Furthermore, by mass%, Si: 1.0% or less, Mn: 1.0% or less, Cr: 20.0-25.0%, Ni: 55.0-65.0%, Mo: 8.0 10.0%, N: 0.001 to 0.3%, Al: 0.1 to 0.4%, Ti: 0.04 to 0.4%, C: 0.1% or less, and Nb: It is good also as a highly corrosion-resistant austenitic stainless steel and Fe-Ni alloy which contain 2.5-4.1% and the remainder consists of Fe and an unavoidable impurity.
本発明の素材として用いた合金についての成分組成を上記のように限定した理由を以下に説明する。
≪Ｃ：０．１mass％以下≫
Ｃは、高温強度を確保するのに有効な元素であるが、過剰に含有すると粒界にＣｒの炭化物を形成し耐食性を劣化させるので、０．１mass％以下に限定した。
≪Ｓｉ：１．０％mass％以下≫
Ｓｉは、脱酸に必要な元素であり、さらに耐酸化性を向上させる元素であるが、１．０mass％を超えて添加すると、連続鋳造時に割れが発生しやすくなる他、高温耐久性をも阻害したりする懸念があるため、範囲は１.０mass％以下とする。
≪Ｍｎ：１．０％mass％以下≫
Ｍｎは、Ｓｉと同様、脱酸に必要な元素である。しかし、１．０mass％を超えて添加すると、耐酸化性の劣化を招く。よって、Ｍｎの範囲は１．０mass％以下とする。
≪Ｎｉ：1４.０〜６５.０mass％≫
Ｎｉはσ相やχ相などの金属間化合物の析出を抑制する上で有効な元素であり、また組織をオーステナイトにする場合には必須な元素である。更には耐応力腐食割れ向上にも効果のある元素であるが、その含有量が６５．０mass％を上回ると熱間加工性の劣化や熱間変形抵抗の増大を招く。よって、Ｎｉの含有量は６５．０mass％以下とした。なお、Ｎｉの含有量は１４．０〜６５．０mass％であることが好ましい。
≪Ｃｒ：１４．０〜２５．０mass％≫
Ｃｒは耐すきま腐食性を向上させるのに有効な元素であり、その効果を得るためには１４．０ｗｔmass％以上含有する必要がある。しかしながら、２５．０ｗｔmass％を超えて含有するとσ相やχ相などの金属間化合物の形成を助長し、かえって耐すきま腐食性を劣化させるので、１４．０mass％〜２５．０mass％とした。
≪Ｍｏ：２．５〜２０．０mass％≫
Ｍｏも耐すきま腐食性を向上させるのに有効な元素であり、その効果を得るためには２．５mass％以上含有する必要がある。しかしながら、２０．０mass％を超えて含有すると、金属間化合物の析出を助長し、耐食性を逆に劣化させてしまうので、２．５mass％〜２０．０mass％とした。
≪Ａｌ：０．４mass％以下≫
Ａｌは強力な脱酸剤であるが、０．４mass％を超えて含有させると金属間化合物の析出を助長させるので、その含有量を０．４mass％以下とした。
≪Ｔｉ：０．０４〜０．４mass％≫
Ｔｉは、炭化物または炭・窒化物の生成元素であり、加工性および耐食性の向上を目的として添加する。しかし、過量を添加すると、靱性を低下し、加工性も劣化するので、０．０４〜０．４mass％とする。
≪Ｎｂ：３．０〜４．２mass％≫
Ｎｂは、Ｔｉと同様効果があるが、３．０以上出なければ加工性および耐食性に対する効果がなく、４．２mass％を超えて添加すると熱延板の靱性が低下するので、３．０〜４．２mass％とする。
The reason why the component composition of the alloy used as the material of the present invention is limited as described above will be described below.
≪C: 0.1 mass% or less≫
C is an element effective for ensuring high-temperature strength, but if contained excessively, it forms Cr carbide at the grain boundary and degrades the corrosion resistance, so it was limited to 0.1 mass% or less.
≪Si: 1.0% mass% or less≫
Si is an element necessary for deoxidation, and further improves oxidation resistance. However, if added over 1.0 mass%, cracking is likely to occur during continuous casting, and high temperature durability is also achieved. The range should be 1.0 mass% or less because there is a risk of obstruction.
≪Mn: 1.0% mass% or less≫
Mn is an element necessary for deoxidation like Si. However, addition exceeding 1.0 mass% causes deterioration of oxidation resistance. Therefore, the range of Mn shall be 1.0 mass% or less.
≪Ni: 14.0-65.0 mass% ≫
Ni is an effective element for suppressing precipitation of intermetallic compounds such as σ phase and χ phase, and is an essential element when the structure is austenite. Furthermore, although it is an element that is also effective in improving stress corrosion cracking resistance, if its content exceeds 65.0 mass%, it causes deterioration of hot workability and increase of hot deformation resistance. Therefore, the Ni content is set to 65.0 mass% or less. In addition, it is preferable that content of Ni is 14.0-65.0 mass%.
≪Cr: 14.0 to 25.0 mass% ≫
Cr is an element effective for improving crevice corrosion resistance, and in order to obtain the effect, it is necessary to contain 14.0 wt% or more. However, if the content exceeds 25.0 wt%, the formation of intermetallic compounds such as σ phase and χ phase is promoted, and the crevice corrosion resistance is deteriorated. Therefore, the content is set to 14.0 mass% to 25.0 mass%.
≪Mo: 2.5 to 20.0 mass% ≫
Mo is also an element effective for improving crevice corrosion resistance. In order to obtain the effect, it is necessary to contain 2.5 mass% or more. However, when it contains exceeding 20.0 mass%, precipitation of an intermetallic compound will be promoted and corrosion resistance will be deteriorated conversely, so it was set as 2.5 mass%-20.0 mass%.
≪Al: 0.4 mass% or less≫
Al is a strong deoxidizer, but if contained in excess of 0.4 mass%, it promotes precipitation of intermetallic compounds, so its content was set to 0.4 mass% or less.
«Ti: 0.04 to 0.4 mass%»
Ti is a generated element of carbide or charcoal / nitride, and is added for the purpose of improving workability and corrosion resistance. However, if an excessive amount is added, toughness is lowered and workability is also deteriorated, so 0.04 to 0.4 mass% is set.
«Nb: 3.0-4.2 mass%»
Nb has the same effect as Ti, but unless it exceeds 3.0, there is no effect on workability and corrosion resistance, and if added over 4.2 mass%, the toughness of the hot-rolled sheet decreases, so 3.0 to 4.2 mass%.
しかしながら、高腐食環境下での使用という観点から見た上記の材料選定は、同時に高温サイクルが付加される本用途の熱的環境においても、好適であるとは言い切れない。 However, the above material selection from the viewpoint of use in a highly corrosive environment cannot be said to be suitable in the thermal environment of this application to which a high temperature cycle is added at the same time.
実際に、脱硝装置の酸化器の後段に当る排気筒内に設置した試験片の腐食に関する結果を、表１に示した。性能試験において耐食性・耐熱性の両特性において最良の結果を得ることができた。 Table 1 shows the results relating to the corrosion of the test pieces installed in the exhaust pipe, which is actually the latter stage of the oxidizer of the denitration apparatus. In the performance test, the best results were obtained in both the corrosion resistance and heat resistance characteristics.
Claims (5)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2007212556A JP2009046716A (en) | 2007-08-17 | 2007-08-17 | Gas-exhausting facility manufactured by using structure material which is suitable for diesel engine exhaust system of marine vehicle, and has heat resistance and high corrosion resistance |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2007212556A JP2009046716A (en) | 2007-08-17 | 2007-08-17 | Gas-exhausting facility manufactured by using structure material which is suitable for diesel engine exhaust system of marine vehicle, and has heat resistance and high corrosion resistance |
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| JP2009046716A true JP2009046716A (en) | 2009-03-05 |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2013040379A (en) * | 2011-08-17 | 2013-02-28 | Sanyo Special Steel Co Ltd | Corrosion resistant alloy excellent in workability |
| JP2013199661A (en) * | 2012-03-23 | 2013-10-03 | Nisshin Steel Co Ltd | Austenitic stainless steel for member of exhaust gas flow channel |
| WO2015129037A1 (en) * | 2014-02-28 | 2015-09-03 | 三菱重工業株式会社 | Sheet metal turbine housing |
| JP2021031720A (en) * | 2019-08-22 | 2021-03-01 | 日本冶金工業株式会社 | HIGH CORROSION RESISTANT Ni-Cr-Mo STEEL EXCELLENT IN WELDABILITY AND SURFACE PROPERTY, AND METHOD FOR MANUFACTURING THE SAME |
| JP7469636B2 (en) | 2020-05-13 | 2024-04-17 | 日本製鉄株式会社 | Stainless Steel Pipes and Welded Fittings |
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2007
- 2007-08-17 JP JP2007212556A patent/JP2009046716A/en not_active Withdrawn
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2013040379A (en) * | 2011-08-17 | 2013-02-28 | Sanyo Special Steel Co Ltd | Corrosion resistant alloy excellent in workability |
| JP2013199661A (en) * | 2012-03-23 | 2013-10-03 | Nisshin Steel Co Ltd | Austenitic stainless steel for member of exhaust gas flow channel |
| WO2015129037A1 (en) * | 2014-02-28 | 2015-09-03 | 三菱重工業株式会社 | Sheet metal turbine housing |
| CN105940203A (en) * | 2014-02-28 | 2016-09-14 | 三菱重工业株式会社 | Sheet metal turbine housing |
| JPWO2015129037A1 (en) * | 2014-02-28 | 2017-03-30 | 三菱重工業株式会社 | Sheet metal turbine housing |
| CN105940203B (en) * | 2014-02-28 | 2019-08-06 | 三菱重工发动机和增压器株式会社 | Metal plate turbine shroud |
| US10400617B2 (en) | 2014-02-28 | 2019-09-03 | Mitsubishi Heavy Industries Engine & Turbocharger, Ltd. | Sheet-metal turbine housing |
| JP2021031720A (en) * | 2019-08-22 | 2021-03-01 | 日本冶金工業株式会社 | HIGH CORROSION RESISTANT Ni-Cr-Mo STEEL EXCELLENT IN WELDABILITY AND SURFACE PROPERTY, AND METHOD FOR MANUFACTURING THE SAME |
| JP7469636B2 (en) | 2020-05-13 | 2024-04-17 | 日本製鉄株式会社 | Stainless Steel Pipes and Welded Fittings |
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