JP2003515673A - Product manufactured from Cr, Al, Si, Ti and an alloy containing one or more of so-called ODEs, and a method for manufacturing the product - Google Patents

Abstract

(57) Abstract: The present invention provides a method for forming a corrosion-resistant oxide layer on a metal surface in an oxidizing atmosphere, wherein one or more metals in the metals chromium, aluminum, silicon and / or titanium are formed. The present invention relates to a metal product containing a large amount of the metal and a method of manufacturing the product. A feature of the present invention is that the metal product has at least 0.5 ppm by weight of hydrogen and at least an adjacent layer on the metal surface, as an elemental form and / or oxide, an oxide layer of the product and a gas surrounding the layer. 0.01% by weight or more of one or several elements having the ability to efficiently dissociate oxygen at the interface with the phase. The group of metals listed below as ODEs, namely the rare earth metals referred to herein as REMs, namely yttrium, the elements with atomic numbers 57-71 and scandium, hafnium, zirconium, niobium, tantalum, titanium, palladium, platinum and Belongs to rhodium.

Description

Detailed Description of the Invention

TECHNICAL FIELD The present invention relates to a method in which one or several of the metals chromium, aluminum, silicon and / or titanium forms a corrosion resistant oxide layer on the surface of a metal product in an oxidizing atmosphere. It relates to a metal product containing an amount of the metal which forms. The present invention also relates to a method for producing the product and use of the product in various applications.

The present invention is specifically applicable to heat resistant materials. Examples of such materials include heat-resistant ferritic stainless steels, austenitic stainless steels and other alloys, which usually contain high proportions of chromium and nickel. In addition, silicon can also be present in significant amounts in these types of stainless alloys. The metal products according to the invention can withstand very high temperatures and can also be made of heating elements or heating element materials, which generally contain 20 to 25% chromium and about 5% aluminum. Examples of aluminum alloy materials include ferritic stainless steels, such as steels for catalytic combustion of automobiles. Another possible application is metal products made of superalloys, alloys containing chromium as the main component, alloys containing aluminum as the main component, and titanium-based alloys or alloys containing significant amounts of titanium. However, it should be understood that the field of application of the present invention should not be limited to the above material types but only a few of the many possible applications.

BACKGROUND OF THE INVENTION Corrosion resistant alloys rely on their materials to form thin corrosion resistant oxide layers of chromium, silicon, aluminum and / or titanium oxides on metal surfaces. It is well known. But on the other hand, the oxide layer is generally
It is also known that microscopic level microscopic holes and cracks cannot be completely protected. In particular, when metal products made from alloys are exposed to high temperatures in an oxidizing environment, defects in the oxide layer can cause significant oxidation of the metal.

It is also known that the growth and sticking of the oxide overcoat is associated with the removal of metal ions from the alloy. According to SE 462 359, when 0.01 to 0.15% of a rare earth metal is added to an austenitic silicon alloy heat resistant material, exfoliation of oxide at high temperature is suppressed.

[0005] Combining other rare earth metals of silicon cerium and the amount, the growth of the SiO ₂ protective layer on the metal surface results in a favorable effect, the SiO ₂ layer, when exposed to a high temperature in an oxidizing environment, the alloy It resists the removal of metal ions, especially chromium ions, from the oxide and prevents the oxide from peeling.

Furthermore, according to SE 421 325 and SE 446 636 it is known to add yttrium to chromium aluminum iron alloys and chromium aluminum silicon iron alloys for the purpose of high temperature materials with excellent oxidation resistance. ing. However, none of these documents reports on improvement of oxidation resistance by adding yttrium. However, in SE 421 325, GB No. 1
Quoting 045 993, it is reported that alloys with less than 20% by weight of chromium and a small amount of yttrium lose oxidation resistance. US Pat. No. 3,027,252 is cited in SE 446 363, which describes iron, chromium,
Aluminum and yttrium alloys exhibit high temperature resistance and good oxidation resistance.

In alloys in general, hydrogen is usually regarded as an impurity. In some steels, hydrogen dissolved in molten steel may cause cracks, so-called white spots, in the cooling process after hot working. To avoid this risk, steels of this type are usually annealed for several days to remove hydrogen. For example, if hydrogen is absorbed during pickling of steel in a non-oxidizing acid, the material may break under less than normal stress. This is called hydrogen embrittlement and can be avoided by heating the material to remove hydrogen. Furthermore, hydrogen is known to reduce the oxidation resistance of alloys of the type mentioned above. For several reasons, hydrogen is usually considered harmful and does not have a positive effect.

As mentioned above, the corrosion resistance of the type of material pointed out in the introduction depends on the presence or absence of a corrosion resistant oxide layer on the metal surface and also on the adherence of the oxide layer to the metal matrix. And whether defects in the form of holes and / or cracks at the microscopic level are present in the oxide layer. It is considered that the growth of the oxide at the interface between the metal and the oxide enhances the adherence of the oxide. "Oxidation of M
Etals (oxidation of the metal), Vol. 51, No. 3/4, 1999, hydrogen in Chromium: high-temperature oxidation rate in the _{O 2,} in effect "for mechanism and scale of sessile oxide growth, B. Toweten et al. Reported that unwanted oxide growth at the oxide / gas interface depends on whether cat ions are transported through the oxide layer, whereas beneficial oxides at the metal / oxide interface. Have been reported to depend on whether oxygen is transported by diffusion or another process. According to the cited article, hydrogen in the metal enhances the transport of metal in the oxide layer, while suppressing the transport of oxygen in the oxide layer, thus increasing the corrosion resistance of the material in the oxidizing environment. It is also reported to make it worse.

DISCLOSURE OF THE INVENTION The present invention provides that the hydrogen in an alloy of the type described above is in the form of elements and / or oxides,
Has the ability to efficiently dissociate oxygen at the interface between the oxide layer of the product and the surrounding gas phase 1
A kind or a plurality of kinds of elements (herein referred to as an element that dissociates oxygen, ODE,
The following group of metals, namely the rare earth metals referred to herein as REM, yttrium, and elements with atomic numbers 57-71, scandium, hafnium, zirconium, niobium, tantalum, titanium, palladium, platinum and (Which belongs to rhodium), thereby completing the oxide protective layer, that is, making the oxide layer more compact, contributing to the removal of pores and other defects and / or the improvement of oxide stickiness, thereby improving the oxidizing environment. Based on the finding that it improves the corrosion resistance of materials. Furthermore, the low anodic dissolution in the liquid chloride environment suggests improved corrosion resistance in liquid media containing chloride ions. In order to achieve a significant improvement, the metal product should be at least 1 m adjacent to the metal surface.
In layers of thickness m, more than 0.5 ppm by weight of hydrogen and ODE totaling more than 0.01% by weight should be present at the same time. The hydrogen content in the surface layer is preferably at least 1 ppm by weight, more preferably at least 2 ppm by weight and at the same time at least 0.03% by weight, preferably at least 0.05% by weight ODE. Combined with. For best results, the layer adjacent to the metal surface of the metal product should have at least 5 ppm by weight hydrogen and a total amount of 0.
It should contain more than 1% by weight ODE. Higher concentrations of hydrogen and ODE are desirable, as claimed. In a preferred embodiment, the ODE is
Any or some of REM and the metals scandium, hafnium, palladium, platinum and rhodium are possible, or basically only REM.

Experiments have revealed that hydrogen in non-ODE alloys of the type mentioned in the introductory part of the invention reduces the oxidation resistance of the material at high temperatures; The addition of ODE to alloys that do not have the effect of reducing the oxidation resistance of the material at high temperatures also; the addition of both ODE and hydrogen to alloys of the above type at high temperatures and also to some erodible liquid media such as chlorides. In a liquid containing matter, it is possible to improve the oxidation resistance of the material; it is possible to find the optimum hydrogen level which gives the best oxidation resistance to the ODE alloy material of the above type at high temperature, but its optimum hydrogen The level depends on the content of the alloy, and in part on the ODE content and also on the oxide forming metals chromium, aluminum, silicon and / or titanium; The optimum hydrogen level that gives the ODE alloy material the best oxidation resistance should be determined by measuring the time required for oxygen absorbed at high temperature to reach a certain level in samples having different hydrogen contents in the oxidizing environment. The oxidation resistance can be significantly improved both at lower and higher hydrogen content than the optimum hydrogen content of the alloy, ie within a certain hydrogen content range including the optimum hydrogen content of the alloy.

From the above observations, the hydrogen content of the alloy according to the invention should generally satisfy the following formula: H _min = 0.1 × H _opt ≦ H _opt ≦ 10 × H _opt = H _max. It can be concluded that H _min = 0.3 × H _opt ≦ H _opt ≦ 3 × H _opt = H _max . In the formula, H _opt is within the framework of the composition of the claimed metallic element, when it is exposed to an oxidizing environment at an elevated temperature, for example at a temperature in the range of 800 to 1100 ° C. Represents the hydrogen content that gives the longest time. The most suitable hydrogen level at the surface should be at least 10 ppm by weight, preferably at least 15 ppm, more preferably at least 20 ppm. To obtain a very high effect, the ODE content in the alloy should be above 0.5% and at least 0.8%.

The maximum level of ODE varies somewhat depending on whether the metal product as a whole contains ODE or if ODE is only present in the surface layer. In the former case, the ODE level should be 3%, in the latter case it should be at most 10%. In the former case, the ODE is in the form of a metal, for example yttrium, or in the form of the so-called misch metal, which basically comprises cerium and lanthanum, and / or an oxide, for example yttria, Y ₂ O ₃ , at most. An amount corresponding to an ODE content of 3% by weight is added.
In the latter case, the ODE can be added directly to the metal surface in order to have a fairly high amount of ODE in the surface layer, ie up to 70% by weight. This application can be carried out, for example, by brushing ODE and an irrelevant carrier onto the surface, or by immersing the product in a liquid medium containing ODE followed by heating with fire and / or drying.

[0013]   R_min From the tests carried out, in order to obtain the best corrosion resistance, the hydrogen level and OD on the product surface
Optimal relationship R expressed in ppm O H / wt% ODE between E levels R_min Is present, and the relationship between hydrogen level and ODE level is R_min≤ R_opt≤ R_max According to R_minAnd maximum value R_maxAs related by (where R _min Is 3, preferably 10, and R_maxIs 200, preferably 50), water
It was shown that the elementary and ODE levels should be adjusted relative to each other.

Hydrogen can be added by metallurgical processing of the melt, for example by injecting steam into the molten alloy. Alternatively, or as a more preferable method, hydrogen may be added in the form of diffusing hydrogen into the metal product forming the solid metal phase. If the metal product is a strip or wire, the diffusion of hydrogen into the product is carried out at elevated temperatures, for example 900 to 1200 ° C., preferably 1050 to 1200 ° C., in a hydrogen gas filled furnace, for example a furnace used for bright annealing. It can be done by continuously passing a strip, wire or equivalent.

Further, the alloy can be produced by a usual method such as an ordinary melting method, a casting method and a hot rolling method. It can also be manufactured by a powder metallurgy method, a spray casting method or any other known method. Also, a new known method can be used.

The test conducted will be described with reference to the drawings. Unless otherwise noted, all applicable units in the text and figures are weight percent and weight p.
pm.

[0017]

【Example】

Example 1 The basic material used in this example is a heat-resistant austenitic Fe, Cr, Ni alloy with the trade name Avesta 353MA®, the nominal composition of which is 0.05 C, 0% by weight. .15N, 25Cr, 35Ni, 1.3Si, 0.
At 05 Ce, the rest is iron and impurities. A sample foil having a thickness of 0.1 mm was prepared from this alloy, mechanically polished with 2400 mesh SiC paper, and then washed with 99.5% ethanol. The test piece was then subjected to a hydrogen absorption treatment. Specifically, hydrogen was absorbed in the test piece by diffusion, and the exposure time was changed to prepare test pieces having different hydrogen absorption amounts. The test piece was immersed in an electrolytic solution containing water, and the test piece was used as a cathode to perform electrolysis at room temperature under atmospheric pressure to allow the test piece to absorb hydrogen. The hydrogen absorption time of each test piece was set to 2, 8, 33, 115, and 350 minutes, respectively. A test piece having a hydrogen level of <1 ppm without hydrogen absorption treatment was used as a reference sample. The test piece subjected to the hydrogen absorption treatment was left for a while to homogenize the hydrogen level in the test piece.

Subsequently, the test piece is 900 containing about 20 mbar O ₂ +2 mbar H ₂ O.
It was exposed to an oxidizing atmosphere at 0 ° C. The amount of oxygen absorbed by the test piece was recorded in μmol O / cm ² while changing the time of exposure to the oxidizing atmosphere. FIG. 1 is a graph showing the amount of oxygen absorbed in μmol O / cm ² with respect to the square root of the time of exposing a test piece to an oxidizing atmosphere.

FIG. 2 is an enlarged view of a portion A surrounded by a frame in FIG. From this graph, the time required for each test piece to absorb oxygen of 11.5 μmol O / cm ² was obtained. FIG. 3 is a graph showing this time against the hydrogen absorption time of each test piece. The time taken to absorb a certain amount of oxygen, in this case 11.5 μmol O / cm ² , is a measure of the corrosion resistance of the test piece in an oxidizing environment.
The longer it takes to absorb oxygen to a certain level, the higher the corrosion resistance. The best values for corrosion resistance were obtained with the test pieces exposed to a hydrogen absorption treatment for 115 minutes. When the hydrogen absorption time was longer than this, the corrosion resistance decreased. 11.
The lowest oxidation resistance indicated by the time required for absorption of 5 μmol O / cm ² was 69 minutes of the test piece which was not subjected to hydrogen absorption treatment, that is, the test piece whose hydrogen absorption time was 0 minutes. The corresponding time for the best specimen exposed to hydrogen absorption for 115 minutes was 89 minutes. This corresponds to an increase in oxygen absorption time of about 30%. The results obtained in this example show that the oxidation resistance can be improved to some extent by the certain amount of hydrogen present in the steel, and the optimum value for the hydrogen content required to obtain the best corrosion resistance. And the improvement in corrosion resistance of this material with 0.05% Ce is relatively small at the total hydrogen level tested of the material.

Example 2 In this example, Fe, Cr, known under the KANTHAL® trademark,
An Al alloy was used. Its nominal basic composition is a maximum of 0.08 C and a maximum of 0.
7Si, maximum 0.4Mn, 22Cr, about 5Al, the rest consisting of iron and inevitable impurities, and yttrium and hydrogen with various contents. The experimental materials were a plate having a thickness of 1 mm and a foil having a thickness of 0.1 mm, respectively. The test piece was prepared in the same manner as in Example 1.

First, a thickness of 1 mm made of a basic hydrogen-free alloy with a low hydrogen content.
Using the above sample as a reference sample, the oxidation resistance of samples containing 0.3% and 1.26% yttrium was examined. The test pieces were vacuum heated to 200-400 ° C., followed by heating under vacuum at 1000 ° C. for 3-4 minutes and then exposed to oxidation at 1000 ° C. at about 20 mbar O ₂ . The oxygen uptake was recorded against the time in the oxidation chamber. The obtained results are graphed and shown in FIG. As can be seen from this graph, the oxidation is dramatically promoted. That is, the oxidation resistance decreases as the yttrium content increases. The sample containing no yttrium showed the highest corrosion resistance.

Next, a 0.1 mm-thick test piece of the same basic alloy containing no yttrium was tested on a sample containing no hydrogen and a sample containing 40 ppm of hydrogen. Oxidation was performed under the same conditions as the above experiment. Again, the hydrogen-free reference material showed the best corrosion resistance. As is clear from FIG. 5, the oxygen absorption amount of the material containing about 40 ppm of hydrogen showed a considerable value.

In the next test, test pieces of the same basic material having a thickness of 0.1 mm and containing 1% of yttrium were exposed to a hydrogen absorption treatment at different times, and then tested. The oxidative exposure of the sample was performed by the same method as the sample of Example 1. The oxygen absorption amount was recorded by changing the treatment time in the oxidizing atmosphere. The result is shown as a graph in FIG. Next, with respect to the test pieces that were exposed to hydrogen absorption for a long time at different times, Example 1
Similarly, the time required to absorb a certain amount of oxygen (here, 6.5 μmol O / cm ² ) was calculated. The result is shown as a graph in FIG.

From the graph of FIG. 7, it can be seen that the yttrium-alloyed material is significantly improved in oxidation resistance by the hydrogen absorption treatment in a short time of 9 minutes. When the hydrogen absorption treatment time was further extended, the oxidation resistance was lowered, and when the hydrogen absorption treatment time was made extremely long, the oxidation resistance was further deteriorated as compared with the material which was not subjected to the hydrogen absorption treatment. Importantly, this experiment found that there was an optimal level. It has been shown that when the alloy contains 1% yttrium, the alloy of the basic composition gives the best results. The reason why the Fe, Cr, and Al alloys absorb hydrogen to reach the optimum hydrogen level showing the best corrosion resistance is faster than that of the Fe, Cr, and Ni alloys (Example 1) is that the former has a higher diffusion rate of hydrogen. Seems to be late. Improvement is 6
． Expressed as the time required to absorb 5 μmol O / cm ² of oxygen, it was about 650% compared to the yttrium alloy that was not hydrogen-absorbed.

In the photograph of FIG. 8A, degassing was performed without hydrogen absorption treatment, and the hydrogen level was 1 p
It is an enlargement of the material surface that is less than pm. Numerous defects in the form of pores were observed in the surface layer of the oxidized material, indicating that this material has a limited resistance to oxidation. FIG. 8C is a further enlargement of the surface of the material exposed to a hydrogen absorption treatment for a maximum time of 120 minutes. On the surface of this material, isolated island-shaped thick oxides are scattered, and thinner oxides are present so as to fill the gaps between them. This result indicates that the metal is transported at a high rate in the oxide of the material with the highest hydrogen content. It then explains why the corrosion resistance of this material is inferior compared to non-hydrogen alloyed materials and materials with the best corrosion resistance. The latter exposed to a hydrogen absorption treatment for 9 minutes is shown in Figure 8B. This material consists essentially of an unbroken oxide film, with no apparent pores or other defects.

Example 3 This example uses powder metallurgically produced chromium, specifically so-called Plansee chromium without yttrium and Plansee chromium with yttrium in the form of 1% Y ₂ O ₃ , and hydrogen levels. Was changed and tested. The test piece was prepared and processed in the same manner as in Example 1. Exposure to hydrogen absorption treatment was performed as in Examples 1 and 2.

A test piece with a thickness of 1 mm was subjected to 900 in about 20 mbar O ₂ +2 mbar H ₂ O.
Oxidized at ° C. FIG. 9 shows the oxygen absorption amount in the oxidizing atmosphere recorded at different times.

From the graph of FIG. 9, yttrium-free yttrium-exposed for a long time in air to absorb a “natural amount” of hydrogen, or exposed to a hydrogen absorption treatment for 4 hours, shows a significant amount of hydrogen. It can be seen that the test piece that holds hydrogen has the lowest oxidation resistance. The hydrogen-free alloy material without yttria showed the same tendency for oxygen absorption as that with yttria. The oxidation resistance of the alloy material, which was added yttria and exposed to a hydrogen absorption treatment for a maximum time of 8 hours, was slightly improved, although not significantly. The oxygen absorption was minimal for the yttria-added alloy material that was exposed to the hydrogen absorption treatment for 4 hours.

From the results of this example shown in FIG. 9, it can be seen that the combination of a certain amount of yttrium and the optimum hydrogen level can have a good effect on the corrosion resistance.

The hydrogen content of the material exposed to the hydrogen absorption treatment for 4 hours was measured to be about 25 ppm. From the weight measurements of the comparative controls, the weight increase of the reference material not exposed to the hydrogen absorption treatment contained yttrium in the form of 1% yttria and about 25 ppm hydrogen.
It was found to be 40% larger than the material according to the invention containing it.

[Brief description of drawings]

FIG. 1 shows commercially available Fe, Cr, Ni, and Si alloy samples containing 0.05% Ce at different hydrogen absorption treatment times, which were exposed to an O ₂ —H ₂ O atmosphere at 900 ° C. It is a figure which shows the change of the oxygen absorption amount with respect to exposure time at the time of doing.

FIG. 2 is an enlarged view of a portion A surrounded by a frame in FIG.

FIG. 3 is a diagram derived from FIG. 2 showing the time required to absorb a certain amount of oxygen with respect to the hydrogen absorption time for the same sample as described above.

FIG. 4 is a graph showing that F containing essentially no hydrogen and having different yttrium contents.
e, Cr, in 20 mbar O ₂ of Al alloy, is a diagram showing an oxidation rate at 1000 ° C..

FIG. 5 is a diagram showing the oxidation rates of commercially available Fe, Cr, Al alloy specimens with different hydrogen levels at 1000 ° C. in 20 mbar O ₂ .

FIG. 6 is the same as FIG. 1 showing the oxidation of a Fe, Cr, Al alloy test piece containing 1% of yttrium in this figure at different hydrogen absorption treatment times in 20 mbar O ₂ + H ₂ O. FIG.

7 is a diagram derived from FIG. 6, showing the time required to absorb a certain amount of oxygen in the same manner as in FIG. 3 with respect to the hydrogen absorption time.

8A, B, C represent surfaces of test pieces exposed to a hydrogen absorption treatment for 0, 9, and 120 minutes, respectively, and evaluated according to FIGS. 6 and 7. FIG.

FIG. 9 shows oxidation of 900% pure yttrium test pieces containing 1% yttrium and yttrium-free test pieces at various hydrogen levels in an oxidizing atmosphere at 900 ° C. Is.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE, TR), OA (BF , BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, G M, KE, LS, MW, MZ, SD, SL, SZ, TZ , UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, B Z, CA, CH, CN, CR, CU, CZ, DE, DK , DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, J P, KE, KG, KP, KR, KZ, LC, LK, LR , LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, R O, RU, SD, SE, SG, SI, SK, SL, TJ , TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW

Claims (30)

[Claims] 1. At least a metal of one or more of the metals chromium, aluminium, silicon and / or titanium in an oxidizing atmosphere to a level that forms a corrosion resistant oxide layer on the metal surface. The ability to efficiently dissociate oxygen at the interface between the oxide layer of the product and the surrounding gas phase, in the form of elemental and / or oxide, with 0.5 wt. 0.01% by weight or more of one or more elements (wherein the element that dissociates oxygen is
ODE, the group of metals listed below, namely the rare earth metals referred to herein as REM: yttrium, elements with atomic numbers 57-71 and scandium,
Hafnium, zirconium, niobium, palladium, platinum, and rhodium) at the same time. 2. The level of ODE in the surface layer is at least 0.03.
%, Preferably at least 0.05% by weight.
Metal products described in. 3. The hydrogen level in the surface layer is at least 1 ppm by weight.
And preferably at least 2 ppm by weight.
Metal products described in. 4. The metal product according to claim 1, wherein the level of ODE is at least 0.1% by weight. 5. The hydrogen level in the surface layer is at least 5 ppm,
Metal product according to claim 3, characterized in that it is preferably at least 10 ppm by weight. 6. Metal product according to claim 5, characterized in that at least the hydrogen content in adjacent layers of the metal surface is at least 15 ppm by weight, preferably 20 ppm by weight. 7. Metal product according to claim 1, characterized in that the alloy contains at least 0.2% by weight of ODE. 8. The alloy comprises at least 0.5% by weight ODE, preferably 0.
Metal product according to claim 7, characterized in that it comprises 8% by weight of ODE. 9. The ODE is basically present only in the surface layer of the metal product,
Metal product according to claim 8, characterized in that the ODE level in its surface layer is at most 5-80% by weight. 10. Metal product according to claim 1, characterized in that the ODE is evenly distributed in the product and is present at a level of 3% by weight. Hydrogen content of 11. alloy _satisfy the relationship of _{H min = 0.1 × H opt ≦} H op t ≦ 10 × H opt = H max, _preferably, H min = 0.3
X H _opt ≤ H _opt ≤ 3 x H _opt = H _max relationship, wherein H _opt is the hydrogen content in the alloy, when the alloy is exposed to an oxidizing environment at high temperature. In each alloy within the range of the composition of the metal element, the hydrogen content is represented such that a certain period of absorbing oxygen becomes the longest) is satisfied. Metal products. 12. The ratio of hydrogen content and ODE content in the surface _{layer, R m in} ≦ wt ppm / ODE weight% ≦ _{R max} of the relationship between hydrogen _{(R min} is 3, preferably 10 and _{R max,} Satisfying the requirement of 200, preferably 50). 13. The metal according to claim 1, wherein the ODE is basically composed of REM and / or one of the metals scandium, hafnium, palladium, platinum and rhodium. Product. 14. The ODE comprises REM.
The metal product according to item 3. 15. One or more of the metals chromium, aluminium, silicon and / or titanium, which are present in an oxidizing environment in such a large amount that they form a corrosion-resistant oxide layer on the surface of the metal. What is claimed is: 1. A method for producing a metal product of an alloy containing one kind or a plurality of kinds, wherein the metal product has at least a layer adjacent to the metal surface,
． It has the ability to efficiently dissociate oxygen at the boundary between the oxide layer of the product and the surrounding gas phase as hydrogen in an amount of 5 ppm by weight or more, and in the form of element and / or oxide, and the total amount is 0. 01% by weight or more, one or several elements (in this specification, the element that dissociates oxygen is ODE, and the group of metals listed below, that is, the rare earth metal, yttrium, atomic number referred to herein as REM) Nos. 57 to 71 and scandium, hafnium, zirconium, niobium, tantalum, titanium, palladium, platinum and rhodium) are contained at the same time. 16. Process according to claim 15, characterized in that the metal product contains at least 1 ppm hydrogen, preferably at least 2 ppm hydrogen. 17. A method according to claims 15 and 16, characterized in that the metal product comprises at least 0.1% ODE in the surface layer. 18. The method according to claim 12, characterized in that the metal product comprises at least 5 ppm hydrogen, preferably at least 10 ppm hydrogen. 19. The method according to claim 18, characterized in that the metal product comprises at least 15 ppm hydrogen, preferably at least 20 ppm hydrogen. 20. The method of claim 17, wherein the metal product comprises at least 0.2% ODE. 21. A metal product according to claim 17, wherein the surface layer comprises at least 0.5% ODE, preferably at least 0.8% ODE. the method of. 22. The method according to claim 15, wherein the ODE is added to the alloy in the essentially molten state. 23. The ODE is added to the surface layer of the product essentially by being applied to the surface of the product, in this case up to a level of 5-80% by weight. 22. A method according to any of claims 15-21. 24. The hydrogen of the surface layer is added by diffusion into the material at an elevated temperature, at least to the essential part, preferably at a temperature in the range of 900 to 1200 ° C. 23. The method according to any one of 15 to 22. 25. The method according to claim 15, wherein hydrogen of the surface layer is added to at least the essential part by electrochemical means, preferably by electric polarization / electrolysis in an aqueous solution. The method described in crab. 26. The ODE added is essentially REM and / or the metal scandium, hafnium, palladium, platinum and rhodium, preferably essentially REM only. The method according to any one of 15 to 25. 27. Use of the metal product according to any one of claims 1 to 14 as a material which is an electric resistance material. 28. Use of the metal product according to any one of claims 1 to 14 as a material which is a carrier of a catalyst. 29. Use of a metal product according to any of claims 1 to 14 as a material for some of the structural elements intended for use in oxidizing environments at temperatures above 400 ° C. 30. A material which is part of a structural element, vessel or pipe designed for a liquid medium containing chloride or halogen ions.
Use the metal product described in any of.