JP2007186727A - Metallic material having excellent metal dusting resistance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a material having excellent metal dusting resistance which is suitable as the material for a cracking furnace, a reforming furnace or the like in petroleum refining, a petrochemical plant or the like. <P>SOLUTION: The metallic material has a composition containing, by mass, 0.01 to 0.4% C, 0.01 to 2.5% Si, 0.01 to 2.5% Mn, 15 to 35% Cr, 20 to 65% Ni, 0.05 to 20% Cu, ≤0.1% S, ≤0.25% N, ≤0.02% O (oxygen) and one or more selected from >0.05 to 0.3% P, 0.001 to 1% Sb and 0.001 to 0.5% Bi, and the balance Fe. The metallic material may comprise one or more selected from ≤10% Co, ≤3% Mo, ≤6% W, ≤1% Ti, ≤2% Nb, ≤0.1% B, ≤1.2% Zr, ≤0.5% Hf, ≤0.1% Mg, ≤0.1% Ca, ≤0.8% Al, ≤0.15% Y, ≤0.15% La and ≤0.15% Ce as well. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention has a high temperature strength, excellent corrosion resistance, and particularly a metal material used in a carburizing gas atmosphere containing hydrocarbon gas, CO gas, etc., particularly a cracking furnace or reformer in a petroleum refining or petrochemical plant. The present invention relates to a metal material excellent in metal dusting resistance suitable as a material for a furnace, a heating furnace or a heat exchanger.

  Demand for clean energy fuels such as hydrogen, methanol, GTL (Gas to Liquids) and DME (dimethyl ether) is expected to increase significantly in the future. Therefore, the reformer for producing such synthesis gas is increased in size, and an apparatus having higher thermal efficiency and suitable for mass production is required. In addition, heat exchange for exhaust heat recovery is also required to improve energy efficiency in reformers in conventional oil refining and petrochemical plants, ammonia production equipment that uses petroleum as a raw material, hydrogen production equipment, etc. Is becoming increasingly used.

  In order to effectively utilize the heat of such a high-temperature gas, heat exchange in a temperature range of 400 to 700 ° C., which is lower than that which has been conventionally targeted, has become important. Corrosion associated with the carburization phenomenon of high Cr—high Ni—Fe alloy-based metallic materials used in exchangers and the like is a problem.

Usually, the synthesis gas produced in the reaction apparatus as described above, that is, a gas containing hydrocarbons such as H ₂ , CO, CO ₂ , H ₂ O and methane is around 1000 ° C. It is in contact at higher temperatures. On the surface of the metal material in this temperature range, elements such as Cr and Si, which have a higher tendency to oxidize than Fe and Ni, are selectively oxidized, and a dense film such as Cr oxide and Si oxide is formed. Corrosion is suppressed. However, in parts where the temperature is relatively low, such as heat exchange parts, the diffusion of elements from the inside of the metal material to the surface becomes insufficient, and in addition to this, the formation of an oxide film having a corrosion inhibiting effect is delayed. Since the gas having such a composition containing hydrocarbons changes to carburizing properties, C enters from the surface of the metal material and carburization occurs.

  In an ethylene cracking furnace tube or the like, when carburization proceeds and a carburized layer made of a carbide such as Cr or Fe is formed, the volume of that portion expands. As a result, fine cracks tend to occur, and in the worst case, the steel pipe being used is broken. Further, when the metal surface is exposed, carbon deposition (coking) using the metal as a catalyst occurs on the surface, which is accompanied by a decrease in the flow path area in the tube and a decrease in heat transfer characteristics.

  On the other hand, in an environment where gas carburization is more severe in reforming furnace tubes, heat exchangers, etc., the carbide becomes supersaturated, and then graphite is deposited directly, so that the base metal is peeled off and the base metal is thinned. In other words, corrosion consumption called metal dusting proceeds. Further, the peeled metal powder serves as a catalyst and generates coking.

  If such cracks, wear, and blockage in the pipe expand, an apparatus failure or the like may occur, and as a result, the operation may be interrupted, and sufficient consideration is required for selecting a material as an apparatus member.

  In order to prevent such corrosion due to carburization or metal dusting, various countermeasures have been conventionally studied.

For example, Patent Document 1 discloses that Cr is 11 to 60% (mass%, the same applies hereinafter) with respect to metal dusting resistance in an atmosphere gas of 400 to 700 ° C. containing H ₂ , CO, CO ₂ , and H ₂ O. .) Fe-based alloys or Ni-based alloys have been proposed. Specifically, an Fe-based alloy containing 24% or more of Cr and 35% or more of Ni, a Ni-based alloy containing 20% or more of Cr and 60% or more of Ni, and an alloy material obtained by adding Nb to these alloys. The invention is shown to be superior. However, merely increasing the Cr or Ni content of the Fe-based alloy or Ni-based alloy does not provide a sufficient carburization suppressing effect, and a metal material having further metal dusting resistance is desired.

  In addition, the method disclosed in Patent Document 2 is based on the group VIII, group IB, group IV and group V of the periodic table for corrosion caused by metal dusting of a high temperature alloy containing iron, nickel and chromium. One or more metals and mixtures thereof are deposited on the surface by conventional physical or chemical means and annealed in an inert atmosphere to form a thin layer having a thickness of 0.01 to 10 μm. This is intended to protect the alloy surface. In this case, Sn, Pb, Bi and the like are particularly effective. However, even if this method is effective in the initial stage, there is a possibility that the thin layer peels off due to long-term use and the effect is lost.

In Patent Document 3, regarding the metal dusting resistance of a metal material in an atmosphere gas of 400 to 700 ° C. containing H ₂ , CO, CO ₂ , and H ₂ O, it is considered that C and C from the viewpoint of solute elements in iron. As a result of investigating the interaction, in addition to enhancing the protection of the oxide film, addition of elements that form stable carbides in metal materials such as Ti, Nb, V, Mo, or Si, Al, Ni, Cu, It is disclosed that an alloy element such as Co having a positive interaction coefficient Ω is effective in suppressing metal dusting. However, increasing Si, Al, etc. may lead to a decrease in hot workability and weldability, and there is room for improvement in terms of manufacturing stability and plant construction.

  Next, in order to block the contact of the carburizing gas with the metal surface, a method of previously oxidizing the metal material and a method of performing the surface treatment are disclosed.

  For example, in Patent Document 4 and Patent Document 5, low Si-based 25Cr-20Ni (HK40) heat-resisting steel and low Si-based 25Cr-35Ni heat-resisting steel are preoxidized in the atmosphere at a temperature in the vicinity of 1000 ° C. for 100 hours or more. And a method for pre-oxidizing austenitic heat-resistant steel containing 20 to 35% Cr in the air is disclosed in Patent Document 6. Further, Patent Document 7 proposes a method for improving carburization resistance by heating a high Ni—Cr alloy in a vacuum to form a scale film. Further, Patent Document 8 proposes a method for improving carburization resistance by forming a concentrated layer of Si or Cr by surface treatment.

Other than the improvement of the metal material itself, a method of suppressing metal dusting by adding H ₂ S to the atmosphere gas in the tube of the synthesis gas reforming apparatus or the manufacturing apparatus has been considered.

Japanese Patent Laid-Open No. 9-78204 JP-A-11-172473 JP 2003-73763 A JP-A-53-66832 JP-A-53-66835 JP 57-43989 A JP 11-29776 A Special Table 2000-509105

  As described above, various techniques for improving the metal dusting resistance of metal materials have been proposed in the past, all of which require special heat treatment and surface treatment, and require cost and labor. . In addition, since there is no scale restoration (scale regeneration) function after the pre-oxidized scale or the surface treatment layer is peeled off, once metal damage occurs, subsequent metal dusting cannot be suppressed.

In addition, as described above, there is a method of suppressing metal dusting by adding H ₂ S to the atmosphere gas in the tube of the synthesis gas reforming apparatus or the manufacturing apparatus, instead of improving the metal material itself. _{Since 2} S may significantly reduce the activity of the catalyst used for the reforming of hydrocarbons, the metal dusting suppression technology by adjusting the components of the atmospheric gas is only applied to a limited extent.

  As described above, although various studies have been made, no technology capable of sufficiently suppressing metal dusting has been obtained at present.

  The present invention has been made in view of the above situation, and its purpose is to suppress the surface reaction of carburizing gas and metal in an ethylene plant cracking furnace tube, reforming furnace tube, etc. It is to provide a metal material having dusting properties.

  As a result of various studies on methods for suppressing the occurrence of metal dusting, the present inventors have obtained the following findings (a) to (f).

  (a) The occurrence of metal dusting is affected by the protection of the oxide film formed on the surface and the development of the carburized layer formed in the interior. That is, when a crack occurs in the oxide film or the oxide film peels off, C enters the metal material from the surface and a carburized layer is formed. Sting occurs.

  (b) In order to increase the protective property of the oxide film, a method of increasing the Cr content and including an element having a strong affinity for oxygen such as Si and Al, as in the general method for increasing the oxidation resistance However, it only suppresses the penetration of C into the metal material for a certain period. And since it is impossible to realize that the oxide film is not cracked or peeled off for a long time, the penetration of C into the metal material is completely blocked only by improving the protection of the oxide film. It is not possible. Therefore, in addition to enhancing the protective properties of the oxide film, by adding elements that form stable carbides in metallic materials such as Ti, Nb, V, and Mo, the intrusion of C into the metallic materials is suppressed. , C penetration rate can be reduced, and the growth of the carburized layer formed inside the oxide film can be suppressed.

  (c) Alternatively, in addition to enhancing the protective property of the oxide film, a carburized layer formed inside the oxide film by adding an element such as Si, Al, Ni, which seems to have little affinity with carbon. Growth can be suppressed. As an element that seems to have little affinity with carbon, there is an element that has an effect of increasing the activity of C, which is a solute element in Fe, in other words, an alloy element that has a positive interaction assistant coefficient Ω. Conceivable. For example, Co, Cu, Ag, As, P, S, and N can be mentioned. Of these, Co and Cu do not deteriorate the properties such as hot workability and toughness of the metal material, and are within the range of possible contents in terms of cost. Effective for improving metal dusting resistance. However, Ag is difficult to use from the viewpoint of cost, As is difficult to use from the viewpoint of toxicity, and P, S and N are alloys because they deteriorate the properties such as hot workability and toughness of metal materials. It is difficult to contain as a component.

  Note that the above findings (a) to (c) have already been disclosed in Patent Document 3.

  (d) The inventors of the present invention have examined the growth phenomenon of the carburized layer formed inside the oxide film in more detail, and as a result, elements that have little affinity with carbon, in other words, mutual By adding an alloying element that has a positive value for the coefficient of action Ω, the growth of the carburized layer formed inside the oxide film can be suppressed by the adsorption / dissociation of carburizing gas on the metal surface. It has been found that because the reaction can be suppressed, the intrusion of C into the steel can be significantly reduced. In addition to the noble metal elements such as Cu, Ag, and Pt, the alloy elements that can suppress the adsorption / dissociation reaction of the carburizing gas on the metal surface are elements of Group VA or VIA of the periodic table. It has been found through experimentation that, in particular, when P, S, Sb or Bi is included as an alloy component, it can be a metal material having excellent metal dusting resistance. It was. Note that P, S, Sb, and Bi may each be contained alone or in combination.

  Here, since P, S, Sb, and Bi are elements that segregate at the grain boundaries of the metal structure, segregation on the metal surface is also expected, so the surface reaction between the carburizing gas and the metal is efficiently performed. Suppression is expected. Therefore, it is considered that there is no need to add P, S, Sb, Bi in particular excessively.

  (e) It should be noted that P and S are already cited in Patent Document 3 as elements that have almost no affinity with carbon and can suppress the growth of the carburized layer formed inside the oxide film when added. However, since S and P are grain boundary segregation elements, properties such as hot workability of the metal material are deteriorated, so that it is difficult to contain them as alloy components. P and S have been positioned as harmful elements such as deteriorating the hot workability of steel, promoting exfoliation of oxide scale, and adversely affecting welding. This is because it has been made possible to reduce as much as possible, or to add an element capable of fixing P or S to fix a trace amount of P or S within the grain of the metal material. However, as a result of subsequent examinations and experiments, if P exceeds 0.05%, a metal material having excellent metal dusting resistance can be obtained, and in terms of hot workability and weldability, It has been found that it is acceptable to contain P up to 0.3%. Moreover, regarding S, since it is necessary to make the upper limit of the content 0.1% from the viewpoint of hot workability and weldability, it is insufficient to impart metal dusting resistance only by the inclusion of S. It may be preferable to include P, Sb, or Bi.

  (f) As described above, in order to improve the metal dusting resistance of the metal material, it is effective to suppress the adsorption / dissociation reaction of the carburizing gas on the metal surface. A metal material containing one or more of Sb and Bi as an alloy component is suitable.

  In addition to a method of increasing the metal dusting resistance of a metal material by including one or more of P, Sb and Bi as an alloy component, a protective oxide scale and a thin layer by surface treatment on the metal surface The metal dusting resistance can be further enhanced by combining the conventional methods such as forming an oxide film to enhance the protective property of the oxide film, or by adding an element having a strong affinity for oxygen such as Si or Al. It is also possible to improve carburization and coking resistance.

  The present invention has been completed based on these findings, and the gist thereof is as shown in the following (1) and (2). Hereinafter, the present invention (1) and the present invention (2), respectively. Collectively, the present invention is sometimes referred to.

  (1) By mass%, C: 0.01 to 0.4%, Si: 0.01 to 2.5%, Mn: 0.01 to 2.5%, Cr: 15 to 35%, Ni: 20 -65%, Cu: 0.05-20%, S: 0.1% or less, N: 0.25% or less, and O (oxygen): 0.02% or less, and P: more than 0.05%. 3% or less, Sb: 0.001 to 1% and Bi: 0.001 to 0.5%, or one or more of them, and the balance is Fe and impurities. Metal material with excellent dusting properties.

(2) The resistance of (1) above, further comprising at least one component selected from at least one of the following first group to sixth group Metal material with excellent metal dusting properties.
First group:% by mass, Co: 10% or less,
Second group:% by mass, Mo: 3% or less and W: 6% or less,
Third group:% by mass, Ti: 1% or less and Nb: 2% or less,
Fourth group:% by mass, B: 0.1% or less, Zr: 1.2% or less, and Hf: 0.5% or less,
Fifth group:% by mass, Mg: 0.1% or less, Ca: 0.1% or less, and Al: 0.8% or less,
Sixth group:% by mass, Y: 0.15% or less, La: 0.15% or less, and Ce: 0.15% or less.

  The metal material of the present invention has an effect of suppressing the surface reaction between the carburizing gas and the metal, and is excellent in metal dusting resistance. Therefore, a cracking furnace, a reforming furnace, etc. in a petroleum refining or petrochemical plant, It can be used for materials such as heating furnaces and heat exchangers, and the durability and operating efficiency of the device can be greatly improved.

  In the present invention, the reason for limiting the composition range of the metal material is as follows. In the following description, “%” display of the content of each element means “mass%”.

C: 0.01 to 0.4%
C needs to be contained in an amount of 0.01% in order to ensure high temperature strength. However, if it exceeds 0.4%, the toughness of the alloy becomes extremely poor, so the upper limit is made 0.4%. Preferably, it is 0.03 to 0.35%, and a more preferable range is 0.03 to 0.3%.

Si: 0.01 to 2.5%
Since Si has a strong affinity with oxygen, it facilitates the uniform formation of a protective oxide scale layer such as Cr ₂ O ₃ . In addition, a Si-based oxide scale is formed in the lower layer of Cr ₂ O ₃ to block the carburizing gas. This effect is exhibited by containing 0.01% or more. However, if it exceeds 2.5%, the toughness decreases, so the upper limit is made 2.5%. A preferable range is 0.1 to 2.5%, and a more preferable range is 0.3 to 2%.

Mn: 0.01 to 2.5%
Mn is necessary for deoxidation and processability improvement, and in order to obtain such an effect, it is necessary to contain 0.01% or more. Further, since Mn is an austenite-forming element, it is possible to substitute a part of Ni with Mn. However, the excessive content of Mn inhibits the carburizing gas barrier performance of the protective oxide scale layer, so the upper limit is made 2.5%. In addition, the preferable range of content of Mn is 0.1 to 2%.

Cr: 15-35%
Cr has an effect of stably forming an oxide scale such as Cr ₂ O ₃ and blocking carburizing gas. In order to obtain such an effect, the content of 15% or more is necessary. However, excessive content degrades the workability and the structure stability, so the upper limit of the content is set to 35%. A preferred range is 18 to 33%. A more preferable range is 23 to 33%.

Ni: 20 to 65%
Ni is an element necessary for obtaining a stable austenite structure depending on the Cr content. Further, when C enters the steel, it has a function of reducing the intrusion rate. Furthermore, it has the function of ensuring the high temperature strength of the metal structure. However, excessive content causes high cost and manufacturing difficulty, so the content of 20 to 65% is appropriate. Preferably it is 25 to 65%, more preferably 28 to 50%.

Cu: 0.05 to 20%
Cu is one of the important elements in the present invention. Cu suppresses the surface reaction between the carburizing gas and the metal, and greatly improves the metal dusting resistance and the like. Further, since it is an austenite-forming element, it is possible to replace part of Ni with Cu. In order to exhibit the effect of improving metal dusting resistance, it is necessary to contain 0.05% or more. However, if the content exceeds 20%, the weldability is remarkably lowered, so the upper limit of the content is made 20%. A preferable content is 0.2 to 15%. A more preferable content is 0.5 to 10%.

S: 0.1% or less S has an effect of suppressing the reaction between the carburizing gas and the metal. However, if excessively contained, hot workability and weldability are remarkably inhibited, so the upper limit of the content needs to be 0.1%. Further, since S has a catalyst poisoning action, it is desirable that the amount of S be as small as possible when a catalyst is used in a plant. In that case, the upper limit of the S content is preferably 0.015%.

  Thus, the upper limit of the S content needs to be 0.1%, and when the catalyst is used in the plant, the upper limit of the S content is preferably 0.015%. The effect of suppressing the reaction between the carburizing gas and the metal may be insufficient with S alone. Therefore, in order to surely obtain the effect of suppressing the reaction between the carburizing gas and the metal, it is necessary to contain one or more of P, Sb and Bi as described later.

  In addition, when one or more of P, Sb, and Bi are contained, it is not necessary to contain S, and therefore, adverse effects due to S cannot be allowed, such as when a catalyst is used in a plant. In some cases, it is desirable to reduce the S content as much as possible. Of course, when the adverse effect due to S can be tolerated, it is possible to contain S if it is 0.1% or less. In this case, if S is contained 0.005% or more, P, The suppression effect by S is added to the effect of suppressing the reaction between the carburizing gas and the metal by containing one or more of Sb and Bi.

N: 0.25% or less N may not be contained. If contained, it has the effect of increasing the high-temperature strength of the metal material. However, if the content exceeds 0.25%, workability is greatly inhibited. Accordingly, the upper limit of the N content is 0.25%. A preferable upper limit is 0.2%. In addition, in order to acquire the effect which raises the high temperature strength of a metal material, it is preferable to make it contain 0.001% or more.

O (oxygen): 0.02% or less O (oxygen) is an impurity element mixed from the raw material when the metal material is melted, and when a large amount of oxide inclusions are present in the steel, In addition to reducing the workability, it also causes wrinkles on the surface of the metal material, so it is desirable to reduce it as much as possible. In the present invention, the allowable content is up to 0.02%.

P: more than 0.05% and not more than 0.3% P is the most important element in the present invention along with Sb and Bi. All of these elements have a function of suppressing the reaction between the carburizing gas and the metal. These elements are effective even when only one kind is contained, and even if they are contained two or more kinds.

  In order to exhibit this effect, the content of P needs to exceed 0.05%. However, if excessively contained, hot workability and weldability are remarkably impaired, so the upper limit of the P content needs to be 0.3%. A preferable P content is 0.06 to 0.25%, and a more preferable P content is 0.085 to 0.2%.

Sb: 0.001 to 1%
Sb is the most important element in the present invention, along with P and Bi. All of these elements have a function of suppressing the reaction between the carburizing gas and the metal. These elements are effective even when only one kind is contained, and even if they are contained two or more kinds.

  In order to exert this effect, the Sb content needs to be 0.001% or more. However, if excessively contained, hot workability and weldability are significantly impaired, so the upper limit of the Sb content needs to be 1%. A preferable Sb content is 0.005 to 0.8%, and a more preferable Sb content is 0.01 to 0.7%.

Bi: 0.001 to 0.5%
Bi, along with P and Sb, is the most important element in the present invention. All of these elements have a function of suppressing the reaction between the carburizing gas and the metal. These elements are effective even when only one kind is contained, and even if they are contained two or more kinds.

  In order to exert this effect, the Bi content needs to be 0.001% or more. However, if excessively contained, hot workability and weldability are significantly impaired, so the upper limit of the Bi content needs to be 0.5%. A preferable Bi content is 0.005 to 0.3%, and a more preferable Sb content is 0.01 to 0.2%.

  The above has described the present invention (1) relating to a metal material having improved metal dusting resistance by containing one or more of P, Sb and Bi as alloy components.

  Next, in addition to the method of the present invention (1), the present invention (2) relating to a metal material having improved strength, ductility and toughness will be described.

According to the present invention (2), the metal material defined in the present invention (1) includes at least one of components selected from at least one of the following first to sixth groups. A metal material excellent in metal dusting resistance, characterized by further containing a seed.
First group:% by mass, Co: 10% or less,
Second group:% by mass, Mo: 3% or less and W: 6% or less,
Third group:% by mass, Ti: 1% or less and Nb: 2% or less,
Fourth group:% by mass, B: 0.1% or less, Zr: 1.2% or less, and Hf: 0.5% or less,
Fifth group:% by mass, Mg: 0.1% or less, Ca: 0.1% or less, and Al: 0.8% or less,
Sixth group:% by mass, Y: 0.15% or less, La: 0.15% or less, and Ce: 0.15% or less.

  Hereinafter, these optional additive elements will be described in order.

First group (mass%, Co: 10% or less)
Since Co has an effect of stabilizing the austenite phase, a part of the Ni component can be substituted. Therefore, Co may be contained as necessary. However, when the content exceeds 10%, the hot workability is lowered. Therefore, when Co is contained, the content is made 10% or less. From the viewpoint of hot workability, a preferred range is 0.01 to 5%, and a more preferred range is 0.01 to 3%.

Second group (mass%, Mo: 3% or less, W: 6% or less)
Since both Mo and W are solid solution strengthening elements, either one or both of them may be contained as necessary. However, when Mo is contained, if the content exceeds 3%, the workability is deteriorated and the structure stability is inhibited. Therefore, when Mo is contained, the content is 3% or less. The Mo content is preferably 0.01 to 2.5%. Further, when W is contained, if the content exceeds 6%, the workability is deteriorated and the structure stability is inhibited. Therefore, when W is contained, the content is set to 6% or less. The W content is preferably 0.01 to 2.5%.

Third group (mass%, Ti: 1% or less, Nb: 2% or less)
Ti and Nb both have the effect of improving the high temperature strength and ductility and toughness when contained in a very small amount, and when P, S or Bi coexist, they have the effect of improving the creep strength. Or you may contain both as needed. However, when Ti is contained, if the content exceeds 1%, workability and weldability are deteriorated. Therefore, when Ti is contained, the content is 1% or less. The Ti content is preferably 0.01 to 1%. Further, when Nb is contained, if the content exceeds 2%, workability and weldability are deteriorated. Therefore, when Nb is contained, the content is 2% or less. The Nb content is preferably 0.01 to 2%.

4th group (mass%, B: 0.1% or less, Zr: 1.2% or less, Hf: 0.5 or less%)
B, Zr, and Hf all have the effect of strengthening grain boundaries and improving hot workability and high-temperature strength characteristics. Therefore, one or more of these may be contained as necessary. Good. However, when B is contained, if the content exceeds 0.1%, the weldability is lowered. Therefore, when B is contained, the content is 0.1% or less. The Zr content is preferably 0.001 to 1.0%. Further, when Zr is contained, if the content exceeds 1.2%, the weldability is lowered. Therefore, when Zr is contained, the content is 1.2% or less. The B content is preferably 0.001 to 0.1%. Further, when Hf is contained, the weldability is lowered when the content exceeds 0.5%. Therefore, when Hf is contained, the content is set to 0.5% or less. The Hf content is preferably 0.001 to 0.5%.

5th group (mass%, Mg: 0.1% or less, Ca: 0.1% or less, Al: 0.8% or less)
Since Mg, Ca, and Al all have the effect of improving hot workability, one or more of these may be included as necessary. However, when Mg is contained, if its content exceeds 0.1%, weldability is deteriorated. Therefore, when Mg is contained, its content is 0.1% or less. The Mg content is preferably 0.0005 to 0.1%. Further, when Ca is contained, if the content exceeds 0.1%, weldability is lowered. Therefore, when Ca is contained, the content is 0.1% or less. The Ca content is preferably 0.0005 to 0.1%. Further, when Al is contained, if the content exceeds 0.8%, the weldability is lowered. Therefore, when Al is contained, the content is set to 0.8% or less. The Al content is preferably 0.001 to 0.8%.

6th group (mass%, Y: 0.15% or less, La: 0.15% or less, Ce: 0.15% or less)
Since Y, La, and Ce all have the effect of improving oxidation resistance, one or more of them may be contained as necessary. However, when these elements are contained, the workability is lowered when the content exceeds 0.15%. Therefore, when the contents are contained, the content is 0.15% or less. Preferably it is 0.0005 to 0.15%.

  In particular, the metal material according to the present invention contains hydrocarbon and carbon monoxide alone or in total at least 1 vol%, hydrocarbon, carbon monoxide and hydrogen alone or in total at least 25 vol%, and in an atmosphere of 1000 ° C. or less. Excellent in metal dusting resistance. For this reason, if this welded joint is applied to a member such as a reaction tube or peripheral equipment in an oil refining heat exchange type hydrocarbon reformer or waste heat recovery unit, the welding workability, durability and safety of the device are improved. It can be greatly improved.

  The metal material according to the present invention is formed into a required shape such as a thick plate, a thin plate, a seamless pipe, a welded pipe, a forged product, a wire rod, or the like by means of melting, casting, hot working, cold working, welding or the like. be able to. Further, it can be formed into a required shape by a technique such as powder metallurgy or centrifugal casting. Surface processing such as pickling, shot blasting, shot peening, mechanical cutting, grinder polishing, and electrolytic polishing can be performed on the surface of the metal material after the final heat treatment. In addition, the metal material according to the present invention can be formed into an irregular shape having one or two or more protrusion shapes on the surface. Furthermore, the metal material according to the present invention can be combined with various carbon steels, stainless steels, Ni-base alloys, Co-base alloys, Cu alloys, etc. to form a multilayer or composite material, and the shape after molding is also exceptional. There are no restrictions. In this case, there are no restrictions on the joining method of the metal material according to the present invention and various steels or alloys, for example, a shape that has been subjected to mechanical joining such as pressure welding or “caulking” or thermal joining such as welding or diffusion treatment. It is also possible.

  EXAMPLES Next, although an Example demonstrates this invention more concretely, this invention is not limited to these Examples.

  A metal material having the chemical composition shown in Table 1 and Table 2 is melted using a high-frequency heating vacuum furnace, a billet is formed, the billet is subjected to hot forging and cold rolling, an outer diameter of 56 mm, and a wall thickness of 6 mm. A steel pipe was prepared. The steel pipe was subjected to solution heat treatment under the following conditions, and a test piece was produced by cutting a part of the steel pipe. The solution heat treatment was performed under conditions of 1160 to 1230 ° C./10 min. Moreover, about some invention steel, it pressed with alloy800H alloy to make clad steel, and produced the test piece similarly.

A test piece having a width of 15 mm and a length of 20 mm was cut out from the metal materials described in Tables 1 and 2. This test piece is kept in a gas atmosphere of 60% CO−26% H ₂ −11.5% CO ₂ −2.5% H ₂ O by volume% at an isothermal temperature of 620 ° C. for a maximum of 1000 hours. The test piece was taken out every time, the surface of the test piece was observed, and the time when occurrence of pitting corrosion (pit) was confirmed was defined as the Pit generation time of the test piece. The results are summarized in Table 3 and Table 4.

  As shown in Table 3, the metal materials having test numbers 21 to 24 whose chemical compositions deviate from the conditions specified in the present invention have a short pitting corrosion (pit) generation time of 500 hours or less and are inferior in metal dusting resistance. . On the other hand, the metal materials of test numbers 1 to 20 and 25 to 44 according to the present invention have a pitting corrosion (pit) generation time of 1000 hours or more as shown in Tables 3 and 4, and are resistant to metal. Excellent dusting properties.

The metal material of the present invention has an effect of suppressing the surface reaction between the carburizing gas and the metal, and has excellent metal dusting resistance. Therefore, a cracking furnace and a reforming furnace in petroleum refining and petrochemical plants, etc. It can be used for materials such as heating furnaces and heat exchangers, and the durability and operational efficiency of the apparatus can be greatly improved.

Claims (2)

  In mass%, C: 0.01 to 0.4%, Si: 0.01 to 2.5%, Mn: 0.01 to 2.5%, Cr: 15 to 35%, Ni: 20 to 65% Cu: 0.05-20%, S: 0.1% or less, N: 0.25% or less and O (oxygen): 0.02% or less and P: more than 0.05% and 0.3% or less , Sb: 0.001 to 1% and Bi: 0.001 to 0.5%, or one or more of them, and the balance consisting of Fe and impurities. Excellent metal material. The metal-resistant metal dab according to claim 1, further comprising at least one component selected from at least one of the following first group to sixth group. Metal material with excellent sting properties.
First group:% by mass, Co: 10% or less,
Second group:% by mass, Mo: 3% or less and W: 6% or less,
Third group:% by mass, Ti: 1% or less and Nb: 2% or less,
Fourth group:% by mass, B: 0.1% or less, Zr: 1.2% or less, and Hf: 0.5% or less,
Fifth group:% by mass, Mg: 0.1% or less, Ca: 0.1% or less, and Al: 0.8% or less,
Sixth group:% by mass, Y: 0.15% or less, La: 0.15% or less, and Ce: 0.15% or less.