TW202323549A - High-temperature resistant alloy and method of fabricating the same - Google Patents

Abstract

The present invention provides a high-temperature resistant alloy and a method of fabricating the same. The alloy material with specific element composition can form a dense oxide layer and have anti-nitridation and/or anti-oxidation in a high-temperature environment with nitrogen and/or oxygen. Therefore, an operation life of the alloy material in the high-temperature environment can be lengthened.

Description

High temperature resistant alloy and its manufacturing method

The present invention relates to a high-temperature resistant alloy and a manufacturing method thereof, in particular to a high-temperature resistant alloy with anti-nitridation and/or anti-oxidation effects and a manufacturing method thereof.

Coal in petrochemical fuels usually contains trace amounts of nitrogen (for example, less than 2 wt%). Therefore, during high-temperature thermal cracking, ammonia (NH ₃ ) and hydrogen cyanide (HCN) will be formed through a series of complex reactions. Among them, ammonia Nitrogen oxides (NO _x ), which are harmful to the environment, will be generated after high-temperature combustion. Therefore, ammonia will be decomposed into nitrogen and hydrogen through the action of high-temperature catalysts, as shown in the following formula (1), so as to avoid the problem of environmental pollution. 2NH ₃ →N ₂ +3H ₂ (1)

In addition, because nitrogen is relatively cheap and has low reactivity, it is also commonly used as a protective atmosphere in the process of metal materials. For example, in the annealing process of heat treatment or when the surface mechanical properties of metal components need to be strengthened, it is usually carried out under the atmosphere of nitrogen.

The above-mentioned ammonia decomposition and the process of using nitrogen as a protective atmosphere are generally carried out in a high temperature environment, especially the ammonia decomposition reaction must be carried out at a high temperature of 1000 ° C to 1100 ° C, so the pipe fittings, rods and plates of the heating equipment The alloy material used must be able to withstand nitriding and/or oxidation in a high temperature environment, so as to prevent the alloy material from being subjected to nitriding and/or oxygenation to form nitrides and/or oxides. If nitrides and/or oxides are formed in the alloy material, there will be differences in strength in local areas, and the nitrides and/or oxides distributed on the grain boundaries will easily become stress concentration points, which will induce cracks and cause damage to equipment parts. Wear and tear, must be replaced frequently, thereby affecting production efficiency and process cost.

At present, the heat-resistant stainless steel 310S of the Wostian iron series is widely used in China as the material for the above-mentioned heating equipment. However, the service life of the stainless steel 310S in high temperature environments is limited. The known improvement method includes adding high-temperature-resistant tungsten to the alloy material, and controlling the alloy composition to limit the content ratio of nickel and chromium. Although this method slightly improves the high-temperature resistance of the alloy material, the nitrogen-resistant The effect of transformation is not significant. Therefore, if in a nitrogen-containing environment, the nitrogen-containing gas will contact the alloy on the surface or through defects, diffuse into the substrate in the form of solid-solution nitrogen atoms and precipitate, and the nitriding reaction is more intense than the oxidation reaction, and the alloy material is relatively strong. Not easy to resist nitriding. Furthermore, the conventional process method of adding tungsten is not easy to produce, and the manufacturing cost is high, which is not economical. In addition, it is known that the iron-nickel-based alloy 800H with a higher nickel content is also used, but when the alloy 800H is used at a temperature above 1000° C., its anti-nitridation effect is not good.

In view of this, there is an urgent need to provide a high-temperature resistant alloy and a manufacturing method thereof, so as to obtain an alloy material having an anti-nitridation and/or anti-oxidation effect in a high-temperature environment containing nitrogen and/or oxygen, thereby increasing the Service life in high temperature applications.

One aspect of the present invention is to provide a high-temperature-resistant alloy, which has a specific element composition, and can form a dense oxide layer on the surface of the alloy in a high-temperature environment containing nitrogen and/or oxygen, thereby achieving anti-oxidation and/or Anti-nitridation effect, so it can prolong the service life of the material.

Another aspect of the present invention is to provide a method for manufacturing a high-temperature resistant alloy, which is to sequentially undergo a smelting process and a processing process for an alloy raw material with a specific element composition, and obtain a high-temperature alloy in a nitrogen-containing and/or oxygen-containing high-temperature environment. High-temperature resistant alloys with anti-oxidation and/or anti-nitridation effects.

According to one aspect of the present invention, a high temperature resistant alloy is provided. Based on the weight of this high temperature alloy as 100 wt%, it contains 25 wt% to 40 wt% of nickel, 5 wt% to 20 wt% of chromium, 35 wt% to 50 wt% of iron, 0.1 wt% to 0.8 Si by wt%, Al from 1.0 wt% to 4.5 wt%, carbon not greater than 0.1 wt%, cerium from 0.01 wt% to 0.1 wt%, and solute elements in a total amount of less than 3.0 wt%. This high temperature resistant alloy system can be applied in the temperature environment from 25°C to 1200°C.

According to an embodiment of the present invention, the high temperature resistant alloy further includes 0.1 wt% to 1.0 wt% niobium.

According to an embodiment of the present invention, the above-mentioned solute elements include titanium, manganese, cobalt, copper and/or vanadium.

According to an embodiment of the present invention, at a temperature ranging from 1000° C. to 1200° C., the surface of the above-mentioned high temperature resistant alloy includes an alumina layer.

According to another aspect of the present invention, a method for manufacturing a high temperature resistant alloy is provided, which includes providing alloy raw materials. Based on the total weight of the alloy raw material as 100 wt%, the alloy raw material contains 25 wt% to 40 wt% of nickel, 5 wt% to 20 wt% of chromium, 35 wt% to 50 wt% of iron, 0.1 wt% to 0.8 wt% % of silicon, 1.0 wt% to 4.5 wt% of aluminum, 0.01 wt% to 0.1 wt% of cerium and the total amount of solute elements is less than 3.0 wt%. Next, a smelting process is carried out on the alloy raw material to obtain die casting ingots or continuous casting billets. Then, the die-cast ingot or continuous casting billet is processed to obtain a high-temperature resistant alloy. The high temperature alloy contains no greater than 0.1 wt% carbon.

According to an embodiment of the present invention, the alloy raw material further includes 0.1 wt% to 1.0 wt% of niobium.

According to an embodiment of the present invention, the above-mentioned solute elements include titanium, manganese, cobalt, copper and/or vanadium.

According to an embodiment of the present invention, the smelting process includes smelting in a fuel heating furnace, smelting in a non-vacuum electric furnace, smelting in a vacuum induction furnace or smelting in a vacuum arc melting furnace.

According to an embodiment of the present invention, the above-mentioned smelting process includes a refining operation.

According to an embodiment of the present invention, the refining operation includes argon blowing oxygen decarburization method, vacuum oxygen blowing decarburization method, electroslag remelting method or vacuum arc remelting method.

Apply the high-temperature resistant alloy and its manufacturing method of the present invention to prepare a high-temperature resistant alloy with specific element composition, so as to have anti-oxidation and/or anti-nitridation effects in high-temperature environments, thereby increasing the alloy material's performance in high-temperature application environments. service life.

As used in this disclosure, "around", "about", "approximately" or "substantially" generally means within 20 percent of the value or range stated , or within 10 percent, or within 5 percent.

Based on the above, the present invention provides a high-temperature resistant alloy and a manufacturing method thereof, in order to obtain a high-temperature resistant alloy with a specific element composition, so as to have anti-nitridation and anti-oxidation effects in a high-temperature environment containing nitrogen and/or oxygen , thereby increasing the service life of alloy materials in high temperature application environments.

The high-temperature resistant alloy of the present invention comprises specific element composition, and it is based on the weight of high-temperature resistant alloy 100wt%, and it is the nickel that comprises 25wt% to 40wt%, the chromium of 5wt% to 20wt%, 35wt% Up to 50 wt% iron, 0.1 wt% to 0.8 wt% silicon, 1.0 wt% to 4.5 wt% aluminum, no more than 0.1 wt% carbon, 0.01 wt% to 0.1 wt% cerium and less than 3.0 wt% in total % of solute elements. In some embodiments, the aforementioned solute elements include titanium, manganese, cobalt, copper and/or vanadium, which are unavoidable trace elements in the manufacturing process, because these solute elements will not affect the alloy when the total content is not high. The material has a significant effect, so it is usually not deliberately and costly to remove it. The above-mentioned iron is a balance amount, which changes according to the addition amount of other metal elements.

Compared with the conventional stainless steel 310S, the high temperature resistant alloy of the present invention has a higher content of nickel and a lower content of chromium. For the high-temperature resistant alloy of the present invention, if the nickel content is less than 25 wt%, the structure of the resulting alloy is relatively unstable; however, if the nickel content is greater than 40 wt%, the material cost to be paid is too high, which is not economical . Furthermore, if the content of chromium is less than 5 wt%, the strength of the obtained alloy is too low, and the effect of high temperature resistance is poor; however, if the content of chromium is greater than 20 wt%, the cost of materials will be too high, which is not economical. benefit.

In some embodiments, at a temperature ranging from 1000° C. to 1200° C., a dense and continuous aluminum oxide protective layer is formed on the surface of the high temperature resistant alloy of the present invention. The known stainless steel 310S will form an oxide layer of chromium oxide (Cr ₂ O ₃ ) at high temperature, but this oxide layer will thicken rapidly at high temperature, and the structure is loose and easy to fall off, so it cannot grow in a high temperature environment. time use. Therefore, the present invention reduces the amount of chromium added (that is, the above-mentioned 5 wt% to 20 wt% of chromium), and by adding aluminum, the alloy material can react with oxygen at high temperature to generate alumina (Al ₂ O ₃ ). In some embodiments, the amount of aluminum added is 1.0 wt% to 4.5 wt%, preferably 1.0 wt% to 2.0 wt%. If the amount of aluminum added is too small (for example, less than 1.0 wt%), a sufficiently dense protective layer cannot be formed at high temperatures, and it cannot have a better high temperature resistance effect; on the contrary, if the amount of aluminum added is too much (for example, more 4.5 wt%), the mechanical properties and ductility of the alloy material will be poor due to the precipitation of brittle intermetallic phases.

The above-mentioned high temperature resistant alloy also contains a small amount of silicon, which is used to increase the reactivity of aluminum, so too little (that is, less than 0.1 wt%) or excessive (that is, more than 0.8 wt%) additions cannot achieve the effect on aluminum. The effect of increased activity. In addition, excess carbon must be removed from the high-temperature resistant alloy of the present invention, and the carbon content is preferably less than 0.1 wt%, so as to avoid generation of carbides and decrease in ductility.

As mentioned above, the high temperature resistant alloy of the present invention contains 0.01 wt% to 0.1 wt% cerium. The addition of cerium can be used to improve the adhesion of the surface oxidation protective layer (namely the above-mentioned aluminum oxide), making it less likely to fall off, thereby improving the high temperature resistance of the alloy material. Therefore, if the amount of cerium added is too small (such as less than 0.01 wt%), the effect of improving the adhesion of the oxide layer cannot be achieved; on the contrary, if the amount of cerium added is too large (such as more than 0.1 wt%), not only the material The cost is too high, and cerium may also form alloy oxides inside the alloy material, which is not conducive to the mechanical properties of the alloy material, and may also lead to a decrease in the effect of increasing the adhesion of the aluminum oxide surface.

In some embodiments, the high temperature resistant alloy may optionally include 0.1 wt% to 1.0 wt% niobium. Adding the aforementioned amount of niobium to the alloy material can reduce the amount of aluminum needed to be added. It should be noted that the addition of the above-mentioned aluminum must reach a certain critical value, so that a dense oxide layer can be effectively formed on the surface of the alloy material, so as to achieve the protection effect in high temperature environment. Furthermore, the addition of niobium can also make the high temperature resistant alloy maintain the compactness of the oxide layer in a nitrogen-containing environment, so as to avoid nitrogen infiltration into the alloy and form nitrides inside. It has better anti-nitridation effect under the high temperature environment of nitrogen.

In some embodiments, the above-mentioned high temperature resistant alloy system can be applied in a temperature environment of 25°C to 1200°C, especially in a temperature environment of 1000°C to 1200°C. In some embodiments, the above-mentioned high temperature resistant alloy can be applied in a high temperature environment (eg, 1000° C. to 1200° C.) including ammonia, nitrogen and/or oxygen.

The manufacturing method of the high temperature resistant alloy of the present invention firstly provides the alloy raw material with specific element composition. In some embodiments, based on the total weight of the alloy raw material is 100 wt%, the alloy raw material comprises 25 wt% to 40 wt% of nickel, 5 wt% to 20 wt% of chromium, 35 wt% to 50 wt% of iron, 0.1 wt% to 0.8 wt% silicon, 1.0 wt% to 4.5 wt% aluminum, 0.01 wt% to 0.1 wt% cerium and solute elements in a total amount of less than 3.0 wt%. In some embodiments, the above-mentioned solute elements include titanium, manganese, cobalt, copper and/or vanadium. In some embodiments, the alloy feedstock may optionally contain 0.1 wt% to 1.0 wt% niobium.

Next, a smelting process is carried out on the alloy raw material to obtain die casting ingots or continuous casting billets. In some embodiments, the melting process includes melting in a fuel-heated furnace, non-vacuum electric furnace (electric arc furnace, EAF) melting, vacuum induction melting (vacuum induction melting, VIM) or vacuum arc melting (vacuum arc melting, VAM) ).

In some embodiments, the smelting process further includes refining the die-cast ingot or the continuous casting billet to obtain the alloy ingot. In the foregoing embodiments, the refining operation includes argon oxygen decarburization (AOD), vacuum oxygen decarburization (VOD), electroslag remelting (ESR) or Vacuum arc remelting (vacuum arc remelting, VAR). Generally speaking, the refining operation can improve the uniformity of the composition and structure of the alloy ingot, reduce coarse inclusions, and have good processing properties, making it easier to carry out subsequent forming and processing.

It should be understood that the above smelting process can be selected according to the element composition of the alloy raw material. For example, after smelting in an electric furnace, the refining operation of decarburization by blowing oxygen with argon is usually used to produce alloy ingots. If the carbon content in the alloy raw material is high, vacuum induction melting can be used, followed by electroslag remelting and refining to reduce the carbon content of the alloy ingot. In addition, if the content of cerium and/or niobium in the alloy raw material is high, it is easy to be lost during smelting due to oxidation. Vacuum induction melting and electroslag remelting can also be used to prevent a large amount of oxidation of cerium and/or niobium , and then obtain an alloy ingot with no hole defect and good quality.

In some embodiments, according to the surface condition of the molded ingot or continuous casting billet (or alloy ingot), a surface treatment step may be optionally performed, which includes surface finishing such as cutting, grinding, and peeling. , to ensure the surface quality of the billet or ingot before subsequent processing.

Then, the mold casting ingot or continuous casting billet (or alloy casting ingot) is processed to produce a high temperature resistant alloy. In some embodiments, the carbon content of the resulting superalloy is no greater than 0.1 wt%. In some embodiments, the processing process includes forging, rolling, wire drawing, pipe threading, welding and other hot or cold processing processes to produce forgings, plates, coils, rods, wires, pipes and other products for the benefit of various types of industrial applications.

The high-temperature-resistant alloy of the present invention has high-temperature-resistant properties, and can have anti-nitridation and/or anti-oxidation effects in high-temperature environments containing ammonia, nitrogen and/or oxygen, so it can be applied to nitrogen-containing high-temperature industrial environments Production equipment (such as heating radiant pipe fittings and heat treatment furnaces), or production equipment that can be applied to the steel pickling industry (such as tanks, load hooks and corrosion-resistant pipelines).

Several examples are used below to illustrate the application of the present invention, but it is not intended to limit the present invention. Those with ordinary knowledge in the technical field of the present invention can make various modifications and changes without departing from the spirit and scope of the present invention. retouch. Embodiment 1 to Embodiment 3 and Comparative Example 1

Example 1 is an alloy ingot made by electric furnace melting and decarburization by blowing oxygen with argon; and Example 2 and Example 3 are alloy ingots made by vacuum induction melting and electroslag remelting. Comparative Example 1 is an alloy ingot obtained by using commercially available tungsten-containing 310S stainless steel. Table 1 shows the composition ratio (wt %) of the alloy ingots of Examples 1 to 3 and Comparative Example 1.

Table 1

The above alloy ingots were forged and rolled to produce high-temperature resistant alloy sheets with a thickness of 10 mm. After the constant temperature oxidation experiment was carried out at 1100 ° C, the oxidation weight gain after 24 hours and 96 hours was observed, as shown in Table 2. Show. Wherein, the oxidation weight gain value represents the mass change of the plate after the aforementioned constant temperature oxidation experiment. The higher the oxidation weight gain value, the faster the oxide layer thickens, so it is easier to fall off, and the alloy material no longer has the ability to resist nitriding or oxidation, and the high temperature resistance is poor.

Table 2

As can be seen from Table 2, the oxidation gain of Comparative Example 1 in 24 hours and 96 hours is far greater than that of Examples 1 to 3, which is due to the oxide layer of chromium trioxide generated by the alloy material of Comparative Example 1, It will thicken rapidly and its structure is loose and easy to fall off, so it cannot be used in a high temperature environment of 1100 °C. In Examples 1 to 3, by adding aluminum, the alloy material forms a protective layer of aluminum oxide at high temperature, and the oxidation weight gain rate is reduced. Furthermore, the addition of cerium in Examples 1 to 3 can improve the adhesion of the oxide layer, making the oxide layer less likely to fall off, thereby improving the high temperature resistance of the alloy material.

Example 1 has good anti-oxidation and anti-nitridation effects due to the addition of a relatively large amount of aluminum. In order to observe the anti-nitridation effect of the alloy material in the case of lower aluminum content, the aluminum content added was reduced in Example 2 and Example 3, but niobium was added in addition in Example 3, and the addition of niobium was added in Example 2 and Example 3. The superalloy 3 was heat-treated at 1100° C. for 96 hours in a nitrogen-containing environment, and its surface microstructure was observed, as shown in FIG. 1A and FIG. 1B . In Example 2, because the amount of aluminum added is reduced, it can be seen from FIG. 1A that a small amount of nitride 100 is produced in the surface microstructure. However, compared with Example 2, Example 3 additionally added niobium, as can be seen from Figure 1B, no nitrides were observed in the surface microstructure of Example 3, so Example 3 does have a better anti-nitridation effect . In other words, in Example 3, by adding niobium, the alloy material still has good anti-nitridation and anti-oxidation effects at a lower aluminum content.

According to the above-mentioned embodiments, compared with the commercially available 310S stainless steel products, the high-temperature-resistant alloy and its manufacturing method provided by the present invention, through the composition of specific elements, allow the alloy material to withstand high-temperature environments containing nitrogen and/or oxygen , can form a dense oxidation protective layer on its surface, and has the effect of anti-nitridation and/or anti-oxidation, so it can prolong the service life of the alloy material.

Although the present invention has been disclosed above with several embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field of the present invention can make various embodiments without departing from the spirit and scope of the present invention. Changes and modifications, so the scope of protection of the present invention should be defined by the scope of the appended patent application.

100: Nitride

According to the following detailed description and reading together with the accompanying drawings, the aspects of the present disclosure can be better understood. It is to be noted that, as is the standard practice in the industry, many features are not drawn to scale. In fact, the dimensions of many of the features are arbitrarily scaled for clarity of discussion. [FIG. 1A] and [FIG. 1B] are surface microstructures of high temperature resistant alloys in some embodiments of the present invention after high temperature heat treatment in a nitrogen-containing environment.

Domestic deposit information (please note in order of depositor, date, and number) none Overseas storage information (please note in order of storage country, institution, date, and number) none

Claims (10)

A high temperature resistant alloy, based on 100 wt% of one of the high temperature resistant alloys, comprising: 25 wt% to 40 wt% nickel; 5 wt% to 20 wt% chromium; 35 wt% to 50 wt% iron; 0.1 wt% to 0.8 wt% silicon; 1.0 wt% to 4.5 wt% aluminum; Not more than 0.1 wt% carbon; 0.01 wt% to 0.1 wt% cerium; and Solute elements whose total amount is less than 3.0 wt%, Wherein the high temperature resistant alloy can be applied in a temperature environment ranging from 25°C to 1200°C. The high temperature resistant alloy as described in Claim 1, further comprising: 0.1 wt% to 1.0 wt% niobium. The high temperature resistant alloy according to claim 1, wherein the solute element includes titanium, manganese, cobalt, copper and/or vanadium. The high temperature resistant alloy according to claim 1, wherein at a temperature of 1000°C to 1200°C, one surface of the high temperature resistant alloy includes an alumina layer. A method of manufacturing a high temperature resistant alloy, comprising: An alloy raw material is provided, wherein the total weight based on one of the alloy raw materials is 100 wt%, and the alloy raw material comprises: 25 wt% to 40 wt% nickel; 5 wt% to 20 wt% chromium; 35 wt% to 50 wt% iron; 0.1 wt% to 0.8 wt% silicon; 1.0 wt% to 4.5 wt% aluminum; 0.01 wt% to 0.1 wt% cerium; and Solute elements whose total amount is less than 3.0 wt%; performing a smelting process on the alloy raw material to obtain a mold ingot or a continuous casting billet; A processing process is performed on the mold ingot or the continuous casting billet to obtain the high temperature resistant alloy, wherein the high temperature resistant alloy contains not more than 0.1 wt% carbon. The method for manufacturing a high-temperature-resistant alloy as described in Claim 5, wherein the alloy raw material further includes: 0.1 wt% to 1.0 wt% niobium. The method for manufacturing a high temperature resistant alloy according to claim 5, wherein the solute element includes titanium, manganese, cobalt, copper and/or vanadium. The method for manufacturing a high-temperature resistant alloy according to claim 5, wherein the melting process includes melting in a fuel heating furnace, melting in a non-vacuum electric furnace, melting in a vacuum induction furnace or melting in a vacuum electric arc melting furnace. The method for manufacturing a high temperature resistant alloy as claimed in claim 5, wherein the smelting process includes a refining operation. The method for manufacturing a high temperature resistant alloy according to claim 9, wherein the refining operation includes an argon blowing oxygen decarburization method, a vacuum oxygen blowing decarburization method, an electroslag remelting method or a vacuum arc remelting method.

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