CN120265803A

CN120265803A - Nickel-based alloys

Info

Publication number: CN120265803A
Application number: CN202380083381.1A
Authority: CN
Inventors: 马丁·奥斯特伦德; 托马斯·赫兰德; 马茨·哈特斯特兰德; 马茨·伦德伯格; 乌尔丽卡·博尔格伦; 克里斯蒂娜·哈拉德逊
Original assignee: Heruimai Europe Middle East And Africa Ltd
Current assignee: Heruimai Europe Middle East And Africa Ltd
Priority date: 2022-12-07
Filing date: 2023-12-06
Publication date: 2025-07-04
Also published as: JP2025539887A; SE546256C2; EP4630592A1; WO2024123229A1; SE2230398A1

Abstract

The invention relates to an alumina forming dispersion strengthened nickel base alloy comprising, in weight percent (wt.%) C0.08 to 0.28, si 0 to 1.50, mn 0 to 0.50, cr 15.0 to 20.0, al 4.0 to 5.0, fe 15.0 to 25.0, N0.030 to 0.075, O0 to 0.1, B0 to 0.02, Y0.01 to 0.1, at least one of Ta, zr, hf, ti and Nb 1.0 to 2.7, balance Ni and impurities normally present, wherein the alloy meets the following requirements (C+N)/(Ta+Zr+Hf Nb+Ti) > 1.4 (value in atomic%) 1, zr+Hf-N > 0.05 (value in atomic%) 2. The alloy of the present invention has excellent hot ductility.

Description

Nickel-based alloy

The present invention relates to an alumina forming nickel-base alloy and to a powder comprising said alumina forming nickel-base alloy. Furthermore, the invention relates to objects made of said alloy or said powder and to the use thereof.

Background

Nickel-based alloys alloyed with aluminum are used in various high temperature applications, such as heat treatment furnaces, because they form stable and protective aluminum oxides on the surface, which will provide very good oxidation resistance.

It is known that objects (e.g., wires or tubes) of nickel-based alloys forming aluminum oxides are difficult to manufacture due to their poor hot ductility. An important factor contributing to this is the intermetallic phase formed during slow cooling/heating at temperatures below about 900 ℃, for example during heat treatment or during heat processing. These intermetallic phases make the alloy hard and brittle and therefore difficult to process.

The present invention aims to solve these problems.

Disclosure of Invention

The present invention thus relates to a nickel-based alloy which fulfils certain requirements with respect to carbon and carbide and nitride forming elements, since the inventors surprisingly found that, if these requirements are met, an object obtained by the alloy or a powder made of the alloy, or after HIP (hot isostatic pressing) will ensure excellent hot ductility. This excellent hot ductility will in turn ensure that substantially no cracks are formed during the hot working manufacturing process when producing the object. Furthermore, the nickel-base alloys of the present invention will provide excellent oxidation resistance and good creep strength at high temperatures for objects composed of said alloys.

Accordingly, the present invention relates to an alumina forming, dispersion strengthened (dispersion hardening) nickel base alloy comprising in weight percent (wt.%):

C0.08 to 0.28;

Si 0 to 1.5;

mn 0 to 0.50;

cr 15.0 to 20.0;

Al 4.0 to 5.0;

Fe 15.0 to 25.0;

n0.030 to 0.075;

O <0.1;

B <0.02;

Y0.01 to 0.1;

At least one of Ta, zr, hf, ti and Nb 1.0 to 2.7;

The balance being Ni and impurities normally present;

and wherein the alloy meets the following requirements:

(C+N)/(Ta+Zr+Hf+Nb+Ti) > 1.40 (value in atomic%) [1];

Zr+Hf-N is not less than 0.05 (value in atomic%) 2.

The inventors have surprisingly found that if the nickel-based alloy is within the above or below defined element ranges and in addition meets the requirements [1] and [2], an object comprising said alloy will ensure excellent hot ductility, which means that the object will be hot worked in a further process to obtain the desired product without crack formation. Furthermore, the nickel-based alloy will have an austenitic microstructure and will have a very good oxidation resistance, in particular at high temperatures, for example above 900 ℃. In addition, the alloy will provide good creep resistance.

According to an embodiment, the alloy may be converted into a powder, which is then used to make an object. The powder may be used in HIP processes or additive manufacturing processes such as 3D printing.

According to an embodiment, the object defined above or below is a HIPed object, such as a part or product, the HIPed object being an object obtained by a hot isostatic pressing process. According to an embodiment, the object defined above or below has been obtained by using additive manufacturing.

The term "desired product" is intended to include, for example, wires, rods, hollow bars, hollow pieces (hollows), belts, tubes, seamless tubes, strips or plates, all of which will be capable of being produced during a thermal processing process without cracking problems. Examples of hot working processes are rolling, forging and/or extrusion.

The nickel-base alloy according to the invention is a dispersion strengthened alloy. This effect is achieved by adding one or more elements selected from Ta, zr, hf, ti and Nb. These elements will form dispersion strengthened particles with C and/or N and optionally added O. Dispersion strengthening contributes to mechanical strength and provides excellent creep strength. Thus, the alloy of the present invention will have excellent mechanical properties, especially at high temperatures.

The invention also relates to a powder made of the alloy of the invention, thereby having the same requirements (i.e. [1] and [2 ]) and alloying element ranges. The powder can be produced by means of powder metallurgy. The powder metallurgy manufacturing process results in a rapidly setting material in which the brittle phase does not have time to form and large compositional changes do not develop due to segregation. Thus, a mixture of rapidly solidifying powders will give the metal body a substantially uniform composition and a substantially uniform distribution of very small dispersed particles.

Examples of suitable applications of the alloy of the invention are as construction material for heat treatment furnaces, in rolls for roller hearth furnaces, as muffle tubes for annealing in a protective atmosphere, as construction material for heating elements, as combustion chamber material in gas turbines, as gas-to-gas heat exchangers, for example in the glass manufacturing industry or in gas turbines, as wire-woven conveyor belts for heat treatment furnaces, as radiant tubes for heating in heat treatment furnaces or as protective tubes for thermocouples.

Detailed Description

The invention will be described in more detail below with reference to various exemplary embodiments. However, the invention is not limited to the exemplary embodiments discussed, but may vary within the scope of the attached claims.

Furthermore, unless explicitly specified otherwise, the dispersion strengthened nickel-base alloys described herein may exist in any possible form and/or state without departing from the invention.

As mentioned above, nickel-based alloys alloyed with aluminum are generally considered difficult to use in the manufacture of objects and components due to the poor hot ductility. The hot ductility of the alloy is a very important factor in achieving ease of production. The inventors have surprisingly found that a nickel-based alloy comprising the above or below mentioned range of alloying elements and fulfilling the following requirements will have excellent hot ductility under HIP conditions and also in the hot working process used in the manufacturing process:

(C+N)/(Ta+Zr+Hf+Nb+Ti) > 1.4 (value in atomic%) [1];

Zr+Hf-N is not less than 0.05 (value in atomic%) 2,

Thus, the alloy of the present invention can be processed into a desired product without substantial formation of cracks in the final product. Thus, without being bound by any theory, it is believed that these requirements will provide a balance between carbide and nitride forming elements, thereby ensuring that no deleterious brittle phases are formed. Thus, the inventors have through extensive research been able to determine which elements of the nickel-based alloys are necessary and to what extent they need to be controlled in order to ensure good hot ductility without affecting weldability, oxidation and creep properties. According to an embodiment, (c+n)/(ta+zr+hf+nb+ti) is 1.50 to 1.75. According to an embodiment, zr+hf-N is 0.18 to 0.38.

Hot Isostatic Pressing (HIP) is a process in which a powder is subjected to elevated temperature and pressure under an inert gas atmosphere. This converts the powder into a mass/object by plastic deformation, flow and diffusion bonding and eliminates internal cavities and micropores. Suitable process temperatures are 900 to 1250 ℃, suitable pressures are 80 to 200MPa, and suitable incubation times are 1 to 3 hours.

When ranges are described in this disclosure, such ranges include the corresponding ends of the ranges unless expressly stated otherwise. Similarly, when an open range is described, unless explicitly stated otherwise, that open range also includes the individual endpoints of that open range.

The importance of the different alloying elements of the nickel-base alloys described herein will be briefly discussed below. All percentages of chemical compositions are given in weight percent (wt%) unless explicitly stated otherwise. As described below, the upper and/or lower limits of any of the individual elements of the compositions described herein may be freely combined within the broadest definition of the composition of the nickel-base alloys described in the claims unless explicitly stated otherwise.

Carbon (C)

The carbon in free form will occupy interstitial sites in the crystal structure, locking dislocation mobility at temperatures up to about 400-500 ℃. Carbon also forms carbides with other elements in the alloy (e.g., ta, ti, hf, zr and Nb). In microstructures with finely dispersed carbides, these carbides provide an obstacle to dislocation movement, even at higher temperatures. Carbon is an essential element for improving creep strength. However, too high a content of C may cause the alloy to become difficult to cold work at lower temperatures (e.g., below 300 ℃) due to deterioration of ductility. Thus, the carbon content is 0.08 to 0.28 wt.%. According to an embodiment, the carbon content is 0.15 to 0.28 wt%, for example 0.20 to 0.28 wt%.

Silicon (Si)

Silicon may be present in an amount of up to 1.5% by weight. Too high a level of Si may lead to an increased risk of precipitation of nickel silicide, which will have an embrittling effect on this type of alloy. According to an embodiment, the Si content is not more than 1.0 wt.%. According to an embodiment, the content of Si does not exceed 0.30 wt.%. According to an embodiment, the content of Si is equal to or greater than 0.001 wt%.

Manganese (Mn)

Manganese is present as an impurity. It may be allowed to be up to 0.50% by weight without negatively affecting the properties. According to an embodiment, mn is an impurity and is present in an amount of up to 0.05 wt.%. According to an embodiment, the Mn content is equal to or greater than 0.001 wt%.

Chromium (Cr)

The chromium content should be at least 15.0 wt.% to ensure that an oxide is obtained that has sufficient oxidation resistance at high temperatures. However, nickel-based alloys containing 4.0 wt.% Al should not contain more than about 20.0 wt.% Cr, as higher levels will increase the risk of brittle phase formation. According to an embodiment, the Cr content is 15.0 to 20.0 wt%, e.g. 17.0 to 19.0 wt%.

Aluminum (Al)

Aluminum is an element that produces a dense and protective scale. Thus, the alloy of the present invention contains at least 4.0 wt% Al, which ensures sufficient oxidation resistance at high temperatures and the oxide completely covers the surface. When the Al content is higher than 5.0 wt%, there is a risk that the hot ductility is significantly deteriorated, and thus the maximum Al content is 5.0 wt%. According to an embodiment, the Al content is 4.0 to 4.5 wt%.

Iron (Fe)

According to the invention, it has been shown that a relatively high Fe content in the nickel-based alloys forming aluminum oxides can have a positive effect. The addition of Fe creates a metallic structure that is energetically unfavorable for the formation of brittle γ', which in turn becomes a risk of the alloy becoming hard and brittle. Thus, the nickel-base alloy comprises at least 15.0 wt.% Fe. However, high levels of iron may lead to the formation of undesirable phases. Thus, the alloy contains no more than 25.0 wt% Fe. According to embodiments, the iron content is 17.0 to 23.0 wt%, e.g. 18.0 to 21.0 wt%, e.g. 18.0 to 20.0 wt%, e.g. 19.0 to 20.0 wt%.

Nickel (Ni)

The alloy according to the invention is nickel-based. Nickel is an alloying element that stabilizes the austenitic structure, thereby counteracting the formation of some brittle intermetallic phases (e.g., sigma phases). The austenitic structure is beneficial, for example, when welding is involved. The austenitic structure also contributes to creep strength at high temperatures. Ni is the remainder alloying element.

Nitrogen and nitrogen

In the same way as C, the free N will occupy interstitial positions in the crystal structure, thereby locking dislocation mobility at temperatures up to about 400 to 500 ℃. Nitrogen will also form nitrides and/or carbonitrides with other elements (e.g., ta, ti, hf, zr and Nb). In microstructures in which these particles are finely dispersed, they give resistance to dislocation movement, especially at higher temperatures. Therefore, N is added to improve creep strength. However, when N is added to an aluminum-alloyed alloy, if it is carelessly added, formation of aluminum nitride will be a problem, and thus the content of N is 0.030 to 0.075 wt%. According to an embodiment, the content of N is 0.040 to 0.060 wt.%.

Oxygen gas

Oxygen may be present in the alloy of the present invention at up to 0.1 wt.%.

Oxygen can help to increase the creep strength of the alloy by forming small oxide dispersoids with Zr, hf, ta and Ti, which when finely distributed in the alloy will improve creep strength. These oxide dispersions have a higher dissolution temperature than the corresponding carbides and nitrides, so oxygen is preferably added for use at high temperatures. Oxygen can also form dispersoids with Al, group 3 elements of the periodic table, sc, Y, and La, and fourteen lanthanoids, and form dispersoids in the same manner as the elements identified above, contributing to higher creep strength of the alloy. According to an embodiment, the nickel-based alloy comprises 20 to 1000 ppm O, for example 50 to 300 ppm O.

Tantalum, hafnium, zirconium, titanium and niobium

The elements Ta, hf and Zr form very small and stable particles with carbon and nitrogen. If these particles are finely dispersed in the tissue, they help lock dislocation movement, thereby increasing creep strength, i.e. providing dispersion strengthening. Such an effect can also be achieved by adding Ti. Niobium also forms stable dispersoids with C and/or N and can therefore be suitably added to the present invention. Based on the above, the combined content of Ta, zr, hf, ti and Nb is 1.0 to 2.7 wt%. According to an embodiment, the combined content of Ta, zr, hf, ti and Nb is 1.4 to 2.3 wt%, for example 1.6 to 2.0 wt%.

Although the combined content is as mentioned above, there are still some limitations in the content of each element, and according to an embodiment, the content of Hf may be 0.3 to 0.7 wt%, according to another embodiment, the content of Zr may be 0.3 to 0.7 wt%, according to an embodiment, the content of Ta may be 0.3 to 0.7 wt%, and according to an embodiment, the content of Nb may be 0.3 to 0.7 wt%.

Yttrium (Y)

Y affects the oxidation properties by doping the oxide formed. Too much alloying of this element generally results in the oxide tending to flake off the surface (spall), and too low an addition of these elements tends to result in poor adhesion of the oxide to the metal surface. Too much alloying of Y also deteriorates hot ductility. Therefore, the content of Y is limited to 0.10% by weight. According to an embodiment, the yttrium is present in an amount of 0.005 to 0.10 wt.%.

Boron (B)

The addition of B has been shown to improve the hot ductility of the nickel-base alloys. However, too high a content of B will lower the melting point, thereby reducing hot workability by narrowing the temperature range in which the material can be processed. Too high a content of B may also deteriorate the required high temperature performance. The powder may contain B in a content of up to 0.02 wt.%. According to an embodiment, B is 0.0001 wt% to 0.02 wt%.

In addition, one of Ca or Mg may be added to improve the hot ductility of the material during the production process. Preferably, the calcium content is at most 0.05 wt.%, suitably equal to or less than 0.01 wt.%. The Mg content may suitably be up to 0.05 wt%.

The nickel-base alloys according to the present invention may also contain impurities that are normally present due to the raw materials used or the manufacturing process chosen. Examples of impurities are S and P. In addition to the elements already specified and discussed above, the alloys described herein may contain up to 0.8 wt.% total of commonly present impurities. In the present invention, impurities that are generally present are understood to mean impurities resulting from the manufacturing process and/or the raw materials used. According to embodiments, the amount of impurities typically present may suitably amount to equal to or less than 0.6 wt%, or to equal to or less than 0.5 wt%.

Furthermore, an alloy, powder or object as defined above or below may contain or consist of the elements defined above or below at any value in the ranges mentioned herein.

Products (e.g. parts) made from the powders defined above or below are mainly intended for use at high temperatures. Examples of applications are structural materials for heat treatment furnaces, rolls for roller hearth furnaces, muffle tubes for annealing in a protective atmosphere, structural materials for heating elements, combustion chamber materials in gas turbines, gas-to-gas heat exchangers, for example in the glass manufacturing industry or in gas turbines, tube reactors in high temperature processes, wire-braid conveyor belts for heat treatment furnaces, heated radiant tubes for heat treatment furnaces or protective tubes for thermocouples.

The invention is illustrated by the following non-limiting examples.

Examples

The different powders were produced by gas atomization in which the original raw material was melted, poured through a ceramic nozzle, and thereafter the melt stream was subjected to high flow of nitrogen. The gas stream breaks the melt stream into small droplets that solidify rapidly into spherical powder particles. The powder is filled into welded sheet metal cans, degassed, sealed and subjected to Hot Isostatic Pressing (HIP). In the HIP process, the filled powder tank was subjected to high temperature (1150 ℃) and high pressure argon atmosphere (100 MPa) for a hold time of 3 hours duration. This process densifies the powder filling the tank into a fully dense body. The HIPed block was then hot rolled in several passes with a total reduction of 70%. From the hot rolled material, a sample for a Gleeble hot ductility tensile test was extracted in the rolling direction.

The composition of the powder produced is shown in table 1 below.

Thermal ductility tests were performed accordingly in the Gleeble system:

The tensile test specimens were heated to a set temperature at a specific heating profile/rate, measured by thermocouples. The set temperature may be reached by heating to the desired temperature (ONH) or by cooling from a higher temperature (ONC). After a specified time at the desired temperature, a tensile test is performed. The area reduction of the tensile specimen at the breaking point was then measured, which provided a measure of the hot ductility. The results of the test are shown in table 2 below.

The hot ductility test in the Gleeble system constitutes a measure of the ability of a material to withstand deformation at high temperatures without crack formation, i.e. hot ductility. As can be seen from table 2, the heating element satisfying all the requirements defined above or below shows good hot ductility in the form of a high value of area reduction at elevated high temperatures in the Gleeble test results. It should be noted that it is believed that good hot ductility of the heating element requires an area reduction of 50% or more at 1150 ℃ and an area reduction of 35% or more at 1050 ℃ in the Gleeble test results.

Claims

1. An alumina-forming dispersion-strengthened nickel-based alloy, the alloy comprising, in weight percent (wt %):

C 0.08 to 0.28;

Si 0 to 1.50;

Mn 0 to 0.50;

Cr 15.0 to 20.0;

Al 4.0 to 5.0;

Fe 15.0 to 25.0;

N 0.030 to 0.075;

O 0 to 0.1;

B 0 to 0.02;

Y 0.01 to 0.1;

At least one of Ta, Zr, Hf, Ti and Nb 1.0 to 2.7;

The balance is Ni and commonly present impurities;

The alloy meets the following requirements:

(C+N)/(Ta+Zr+Hf+Nb+Ti)≥1.4 (value in atomic %) [1];

Zr+Hf-N≥0.05 (value in atomic %) [2].

2. The alumina forming dispersion strengthened nickel-based alloy according to claim 1, wherein the C content is 0.15 wt. % to 0.28 wt. %, such as 0.20 wt. % to 0.28 wt. % C.

3. The alumina forming dispersion strengthened nickel-based alloy according to claim 1 or 2, wherein the Si content does not exceed 0.30 wt. %.

4. The alumina forming dispersion strengthened nickel-based alloy according to any one of claims 1 to 3, wherein Mn is an impurity and its content is at most 0.05 wt%.

5. The alumina forming dispersion strengthened nickel-based alloy according to any one of claims 1 to 4, wherein the content of Cr is 17.0 wt% to 19.0 wt%.

6. The alumina forming dispersion strengthened nickel-based alloy according to any one of claims 1 to 5, wherein the content of Fe is 18.0 wt. % to 21 wt. %, such as 18.0 wt. % to 20.0 wt. %.

7. The alumina forming dispersion strengthened nickel-based alloy according to any one of claims 1 to 6, wherein the oxygen content is 20 ppm to 1000 ppm, such as 50 ppm to 300 ppm O.

8. The alumina forming dispersion strengthened nickel-based alloy according to any one of claims 1 to 7, the combined content of Ta, Zr, Hf, Ti and Nb being 1.4 to 2.3 wt. %, such as 1.6 to 2.0 wt. %.

9. A powder consisting of the alumina-forming dispersion-strengthened nickel-based alloy according to any one of claims 1 to 8.

10. An object made from the alumina forming dispersion strengthened nickel-based alloy or powder as claimed in any one of claims 1 to 9.

The object according to claim 10 , wherein the object is a HIPed object.

12. An object according to claim 10 or claim 11, wherein the object is in the form of a tube, hollow piece, block, rod, strip, ribbon, plate or wire.