A high-chromium molybdenum age hardenable nickel-based alloy

Abstract

The present application relates to a kind of high-chromium molybdenum aging strengthening type nickel-based alloys, and the weight percentage of each component of the alloy is as follows: C: 0.03-0.1%, Si: 0.3-1.0%, Mn: 0.4-1.0%, Cr: 24.0-30.0%, Mo: 7.0-8.0%, Al: 1.0-2.5%, Ti: 0.5-2.0%, Fe: 0.9-5.0%, Zr≤0.1%, Mg≤0.05%, B≤0.005%, Nb+Ta: 2.0-4.0%, and the balance is Ni, and the alloy satisfies the condition Cr%+1.5×(Mo%+Nb%)≥40.The alloy described in the present application has good corrosion resistance, oxidation resistance, thermal stability and high-temperature mechanical properties, etc.

Description

Technical Field

[0001] This invention relates to a metallic material, and more particularly to a high-chromium-molybdenum age-hardening nickel-based alloy. Background Technology

[0002] Nickel-based alloys can be further classified according to their main properties into nickel-based high-temperature alloys, nickel-based corrosion-resistant alloys, nickel-based wear-resistant alloys, nickel-based precision alloys, and nickel-based shape memory alloys.

[0003] Nickel-based corrosion-resistant alloys typically contain nickel, chromium, molybdenum, iron, copper, and niobium as their main alloying elements. They possess excellent comprehensive properties and are resistant to various acid corrosions and stress corrosion. The earliest application (produced in the United States in 1905) was the nickel-copper (Ni-Cu) alloy, also known as Monel alloy (Ni 70 Cu30). Other alloys include nickel-chromium (Ni-Cr) alloys (nickel-based heat-resistant alloys, specifically heat- and corrosion-resistant alloys within the broader category of corrosion-resistant alloys), nickel-molybdenum (Ni-Mo) alloys (primarily referring to Hastelloy B series), and nickel-chromium-molybdenum (Ni-Cr-Mo) alloys (primarily referring to Hastelloy C series). Meanwhile, pure nickel is also a typical representative of nickel-based corrosion-resistant alloys. These nickel-based corrosion-resistant alloys are mainly used in the manufacture of components for various corrosive environments in the petroleum, chemical, and power industries.

[0004] Nickel-based superalloys were first developed in the late 1830s. Britain first produced the nickel-based alloy Nimonic 75 (Ni-20Cr-0.4Ti) in 1941; to improve creep strength, aluminum was added, resulting in Nimonic 80 (Ni-20Cr-2.5Ti-1.3Al). The United States developed nickel-based alloys in the mid-1940s, the Soviet Union in the late 1940s, and China in the mid-1950s. The development of nickel-based alloys involved two aspects: innovation in alloy composition and production processes. In the early 1950s, the development of vacuum melting technology created conditions for refining nickel-based alloys containing high levels of aluminum and titanium. Early nickel-based alloys were mostly wrought alloys. In the late 1950s, due to the increased operating temperature of turbine blades, higher high-temperature strength was required for alloys. However, high strength made deformation difficult, or even impossible. Therefore, investment casting was adopted, leading to the development of a series of casting alloys with good high-temperature strength. In the mid-1960s, directionally solidified and single-crystal superalloys, as well as powder metallurgy superalloys, with even better performance were developed. To meet the needs of ships and industrial gas turbines, a number of high-chromium nickel-based alloys with good resistance to hot corrosion and stable microstructure have been developed since the 1960s. In the approximately 40 years from the early 1940s to the late 1970s, the operating temperature of nickel-based alloys increased from 700℃ to 1100℃, an average increase of about 10℃ per year.

[0005] With the development of the equipment manufacturing industry, the requirements for materials in terms of corrosion resistance, oxidation resistance, thermal stability and high-temperature mechanical properties are becoming increasingly stringent due to the different application scenarios and equipment performance requirements. Existing materials are struggling to meet these requirements. Summary of the Invention

[0006] The purpose of this invention is to provide a high-chromium-molybdenum age-hardening nickel-based alloy. This material has good corrosion resistance, oxidation resistance, thermal stability and high-temperature mechanical properties, and can be used to manufacture key components such as oil and gas drilling tools (e.g., drill collars, drill pipes, oil well pipes, pressure-bearing shells, fasteners, etc.), combustion chambers and flame tubes of engines or gas turbines.

[0007] The technical solution of this invention is:

[0008] A high-chromium-molybdenum age-hardening nickel-based alloy, the alloy's components by weight percentage are as follows: C: 0.03–0.1%, Si: 0.3–1.0%, Mn: 0.4–1.0%, Cr: 24.0–30.0%, Mo: 7.0–8.0%, Al: 1.0–2.5%, Ti: 0.5–2.0%, Fe: 0.9–5.0%, Zr≤0.1%, Mg≤0.05%, B≤0.005%, Nb+Ta: 2.0–4.0%, balance Ni, the alloy's Cr%+1.5×(Mo%+Nb%)≥40.

[0009] A further technical solution is that the weight percentage of each component in the alloy is as follows: C: 0.03–0.05%, Si: 0.3–1.0%, Mn: 0.6–1.0%, Cr: 27.0–30.0%, Mo: 7.5–8.0%, Al: 1.0–1.5%, Ti: 0.5–0.9%, Fe: 1.2–5.0%, Zr≤0.1%, Mg≤0.05%, B≤0.005%, Nb+Ta: 2.0–4.0%, with the balance being Ni. The alloy's Cr% + 1.5 × (Mo% + Nb%) ≥ 40. This material exhibits excellent corrosion resistance and can be used to prepare products requiring high corrosion resistance.

[0010] A further technical solution is that the weight percentage of each component in the alloy is as follows: C: 0.05–0.1%, Si: 0.3–0.5%, Mn: 0.4–0.6%, Cr: 25.0–27.0%, Mo: 7.0–7.5%, Al: 1.2–1.5%, Ti: 0.8–1.5%, Fe: 2.5–3.0%, Zr≤0.1%, Mg≤0.05%, B≤0.005%, Nb+Ta: 2.5–3.5%, with the balance being Ni. The alloy's Cr% + 1.5 × (Mo% + Nb%) ≥ 40. This material exhibits excellent processing performance, structural stability, and mechanical properties at temperatures ranging from 600℃ to 1000℃, and can be used to prepare products requiring high-temperature resistance.

[0011] A further technical solution is that the weight percentage of each component in the alloy is as follows: C: 0.04–0.08%, Si: 0.5–1.0%, Mn: 0.4–0.5%, Cr: 26.0–29.0%, Mo: 7.0–7.5%, Al: 1.8–2.5%, Ti: 0.5–1.0%, Fe≤3.0%, Zr≤0.1%, Mg≤0.05%, B≤0.005%, Nb+Ta: 2.5–3.7%, with the balance being Ni. The alloy has a Cr% + 1.5 × (Mo% + Nb%) ≥ 40. This material possesses excellent strength, toughness, and oxidation resistance, and can be used to prepare products requiring high-temperature resistance.

[0012] The sum of Al% + Ti% + Nb% + Ta% in the above alloy is 4 to 7.

[0013] The preparation method of the alloy described in this invention is as follows: take each component, smelt it using vacuum induction melting + electroslag remelting or vacuum arc remelting process, and then forge + hot rolling / cold rolling + heat treatment to obtain a high chromium molybdenum age-strengthened nickel-based alloy.

[0014] The main roles of various elements in alloys:

[0015] Nickel: a matrix element; high nickel content ensures resistance to stress corrosion. Solid solution strengthening elements dissolve into the nickel matrix to produce solid solution strengthening, and nickel forms a strengthening phase with age-hardening elements.

[0016] Chromium: Solid solution strengthening; in high-temperature environments, it forms a dense oxide film, improving oxidation resistance; in corrosive environments, it forms a dense passivation film, improving corrosion resistance, especially pitting corrosion resistance.

[0017] Molybdenum: Solid solution strengthening; improves corrosion resistance, especially pitting corrosion resistance.

[0018] Iron: Reduces the tendency to carburize at high temperatures, thus reducing alloy costs.

[0019] Silicon and manganese: deoxidation; improve processing performance.

[0020] Carbon: Deoxidized during vacuum smelting; forms highly stable carbides such as titanium carbide and niobium carbide, which hinder grain growth at high temperatures, pin grain boundaries, and improve strength.

[0021] Aluminum and titanium: During aging, dispersed reinforcing phases such as Ni3Al, Ni3Ti, and Ni3(Ti, Al) are precipitated, which improves strength; aluminum improves oxidation resistance.

[0022] Niobium: During aging, dispersed Ni3Nb is precipitated, which improves strength; Ni3 (Ti, Al, Nb) is formed, which also improves strength.

[0023] Boron, zirconium, and magnesium: purify grain boundaries; improve high-temperature mechanical properties; improve processing performance.

[0024] The beneficial effects of the alloy described in this invention are as follows:

[0025] (1) The alloy design concept of precipitation strengthening is adopted. By promoting the precipitation of a large number of uniformly dispersed secondary strengthening phases inside the alloy, the alloy can obtain good strength properties. At the same time, under the premise of ensuring the stability of the alloy structure, more chromium elements are added, thereby obtaining excellent oxidation resistance and corrosion resistance.

[0026] (2) In order to improve the solid solution strengthening effect, improve the oxidation resistance and corrosion resistance, the chromium content should be increased as much as possible (the chromium content of conventional high temperature alloys is 10-20%, and the minimum chromium content of this invention is 24% or more); in order to ensure the stability of the material structure during high temperature use, the chromium content should be controlled below 30% to avoid the formation of α-Cr and to prevent the precipitation of TCP phase during aging.

[0027] (3) Under the premise of ensuring the molding and other process performance, the molybdenum content should be increased as much as possible to improve the solid solution strengthening effect and corrosion resistance; carbon, silicon, manganese, boron, zirconium, magnesium and other process elements are used in combination to improve purity and process performance; ensure that enough aging strengthening elements are added, and aluminum, titanium, niobium and other aging strengthening elements are used in combination to generate multiple strengthening phases and improve the strengthening effect; add appropriate amounts of solid solution strengthening and aging strengthening elements to achieve a composite strengthening effect.

[0028] (4) Compared with traditional age-hardening alloys, the alloy material of the present invention has a higher chromium and molybdenum content and better corrosion resistance.

[0029] According to the applicant's experiments, the alloy has a Cr% + 1.5 × (Mo% + Nb%) ≥ 40, high pitting corrosion resistance equivalent, and good mechanical properties. The nickel-based alloy of this invention possesses excellent corrosion resistance, oxidation resistance, thermal stability, and high-temperature mechanical properties. It can be used as a high-temperature alloy, a corrosion-resistant alloy, and also as an alloy material used under conditions of high temperature, high pressure, simultaneous corrosion, and other complex working conditions. It features strong oxidation resistance, good thermal stability, and high strength.

[0030] The present invention will be further described below with reference to specific embodiments, but this does not limit the present invention to the scope of the embodiments described. Attached Figure Description

[0031] Figure 1 The image shows the microstructure of the alloy described in Example 1.

[0032] Figure 2 The image shows the microstructure of the alloy described in Example 2.

[0033] Figure 3 The image shows the microstructure of the alloy described in Example 3.

[0034] Figure 4 This is a microstructure diagram of the alloy described in Example 4. Detailed Implementation

[0035] Example 1

[0036] (1) According to the weight percentage of each component: C: 0.08%, Si: 0.4%, Mn: 0.5%, Cr: 28.9%, Mo: 7.5%, Al: 1.5%, Ti: 1.1%, Fe: 1.8%, Zr: 0.06%, Mg: 0.01%, B: 0.002%, Nb: 3.1%, Ta: 0.3%, with the balance Ni, each component is taken and smelted by vacuum induction melting + electroslag remelting process, and then forged + hot rolling + heat treatment to obtain a high chromium molybdenum age-strengthened nickel-based alloy.

[0037] (2) Cr%+1.5×(Mo%+Nb%)=44.8, which has high pitting resistance equivalent.

[0038] (3) Good processability, with a forging and hot rolling yield of ≥82%.

[0039] (4) Microstructure: austenite + carbonitrides (see Figure 1 ).

[0040] (5) Mechanical properties: at room temperature, tensile strength ≥930MPa, elongation ≥30%, hardness ≥260HB, impact energy ≥50J; at 850℃, tensile strength ≥380MPa, yield strength ≥300MPa, elongation ≥40%.

[0041] Example 2

[0042] (1) According to the weight percentage of each component: C: 0.03%, Si: 0.3%, Mn: 0.6%, Cr: 29.8%, Mo: 7.8%, Al: 1.2%, Ti: 0.9%, Fe: 1.2%, Zr: 0.04%, Mg: 0.008%, B: 0.002%, Nb: 3.0%, Ta: 0.1%, with the balance Ni, each component is taken and smelted by vacuum induction melting + vacuum consumable remelting process, and then forged + hot rolling + heat treatment to obtain a high chromium molybdenum age-strengthened nickel-based alloy.

[0043] (2) Cr%+1.5×(Mo%+Nb%)=45, with high pitting resistance equivalent, low carbon content, and excellent corrosion resistance.

[0044] (3) Good processability, with a forging and hot rolling yield of ≥75%.

[0045] (4) Microstructure: austenite + carbonitrides (see Figure 2 ).

[0046] (5) Mechanical properties: at room temperature, tensile strength ≥900MPa, elongation ≥30%, hardness ≥250HB, impact energy ≥60J; at 850℃, tensile strength ≥350MPa, yield strength ≥270MPa, elongation ≥60%.

[0047] Example 3

[0048] (1) According to the weight percentage of each component: C: 0.05%, Si: 0.3%, Mn: 0.6%, Cr: 25.3%, Mo: 7.5%, Al: 1.3%, Ti: 0.9%, Fe: 2.5%, Zr: 0.04%, Mg: 0.01%, B: 0.003%, Nb: 2.5%, with the balance Ni, each component is taken and smelted by vacuum induction melting + electroslag remelting process, and then forged + hot rolling + heat treatment to obtain a high chromium molybdenum age-strengthened nickel-based alloy.

[0049] (2) Cr%+1.5×(Mo%+Nb%)=40.3, with high pitting resistance equivalent.

[0050] (3) Good processability, with a forging and hot rolling yield of ≥93%.

[0051] (4) Microstructure: austenite + carbonitrides; after holding at 850~900℃ for 100~500h, the microstructure showed no significant changes and was stable (see Figure 3 ).

[0052] (5) Mechanical properties: at room temperature, tensile strength ≥870MPa, elongation ≥35%, hardness ≥240HB, impact energy ≥60J; at 850℃, tensile strength ≥260MPa, yield strength ≥210MPa, elongation ≥90%.

[0053] Example 4

[0054] (1) According to the weight percentage of each component: C: 0.06%, Si: 0.6%, Mn: 0.4%, Cr: 29.0%, Mo: 7.1%, Al: 2.1%, Ti: 0.8%, Fe: 0.9%, Zr: 0.07%, Mg: 0.01%, B: 0.003%, Nb: 3.3%, Ta: 0.4%, with the balance Ni, each component is taken and smelted by vacuum induction melting + vacuum consumable remelting process, and then forged + hot rolling / cold rolling + heat treatment to obtain a high chromium molybdenum age-strengthened nickel-based alloy.

[0055] (2) Cr%+1.5×(Mo%+Nb%)=44.6, high pitting resistance equivalent; high Cr and Al content, excellent antioxidant properties.

[0056] (3) The yield of forging and hot rolling is ≥70%.

[0057] (4) Microstructure: austenite + carbonitrides (see Figure 4 ).

[0058] (5) Mechanical properties: at room temperature, tensile strength ≥950MPa, elongation ≥25%, hardness ≥280HB, impact energy ≥40J; at 850℃, tensile strength ≥400MPa, yield strength ≥320MPa, elongation ≥40%.

[0059] Conclusion: The nickel-based alloy of this invention has high chromium and molybdenum content, resulting in good corrosion resistance; high chromium and aluminum content, resulting in good oxidation resistance; by controlling the content of chromium, molybdenum, titanium, and aluminum, harmful phases such as α-Cr and TCP are effectively controlled; the presence of carbonitrides in the microstructure acts as a pinning agent for grain boundaries, refining the grains. The alloy of this invention exhibits excellent comprehensive mechanical properties: room temperature mechanical properties: tensile strength ≥870MPa, elongation ≥25%, hardness ≥240HB, impact energy ≥40J; 850℃ mechanical properties: tensile strength ≥260MPa, yield strength ≥210MPa, elongation ≥40%. Therefore, the excellent corrosion resistance, oxidation resistance, thermal stability, and high-temperature mechanical properties of the nickel-based alloy of this invention can ensure its service performance under high temperature, high pressure, corrosion, and other complex working conditions.

[0060] This invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of this invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all of these fall within the scope of protection claimed by this invention.

Claims

1. A high-chromium-molybdenum age-hardening nickel-based alloy, characterized in that, The alloy has the following weight percentages: C: 0.03–0.1%, Si: 0.3–1.0%, Mn: 0.4–1.0%, Cr: 25.3–30.0%, Mo: 7.0–7.8%, Al: 1.0–2.5%, Ti: 0.5–2.0%, Fe: 0.9–5.0%, Zr≤0.1%, Mg≤0.05%, B≤0.005%, Nb+Ta: 2.0–4.0%, with the balance being Ni. The alloy has a Cr%+1.5×(Mo%+Nb%)≥40. The alloy is obtained by smelting, followed by forging, hot rolling / cold rolling, and heat treatment.

2. The alloy according to claim 1, characterized in that, The alloy composition by weight percentage is as follows: C: 0.03–0.05%, Si: 0.3–1.0%, Mn: 0.6–1.0%, Cr: 27.0–30.0%, Mo: 7.5–7.8%, Al: 1.0–1.5%, Ti: 0.5–0.9%, Fe: 1.2–5.0%, Zr≤0.1%, Mg≤0.05%, B≤0.005%, Nb+Ta: 2.0–4.0%, with the balance being Ni.

3. The alloy according to claim 1, characterized in that, The alloy composition by weight percentage is as follows: C: 0.05–0.1%, Si: 0.3–0.5%, Mn: 0.4–0.6%, Cr: 25.3–27.0%, Mo: 7.0–7.5%, Al: 1.2–1.5%, Ti: 0.8–1.5%, Fe: 2.5–3.0%, Zr≤0.1%, Mg≤0.05%, B≤0.005%, Nb+Ta: 2.5–3.5%, balance Ni.

4. The alloy according to claim 1, characterized in that, The alloy composition by weight percentage is as follows: C: 0.04–0.08%, Si: 0.5–1.0%, Mn: 0.4–0.5%, Cr: 26.0–29.0%, Mo: 7.0–7.5%, Al: 1.8–2.5%, Ti: 0.5–1.0%, Fe≤3.0%, Zr≤0.1%, Mg≤0.05%, B≤0.005%, Nb+Ta: 2.5–3.7%, with the balance being Ni.

5. The alloy according to any one of claims 1-4, characterized in that, The sum of Al%, Ti%, Nb%, and Ta% in the alloy is 4 to 7.

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