Nickel-iron alloy, raw part and component
An iron-based alloy with tailored compositions addresses the challenge of high operating temperatures and material costs, enhancing strength and corrosion resistance, enabling efficient machining and increased machine performance.
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Applications
- Current Assignee / Owner
- SIEMENS ENERGY GLOBAL GMBH & CO KG
- Filing Date
- 2024-11-11
- Publication Date
- 2026-05-13
AI Technical Summary
Current materials for rotor forging discs, such as NiCrMoV and CrMoWVNbN, do not adequately address the need for higher operating temperatures beyond 923K, and nickel-based materials are costly and have longer processing times.
Development of an iron-based alloy with specific compositions, including elements like Chromium, Molybdenum, and Titanium, to enhance strength and corrosion resistance, allowing for a 2- or 3-stage QHT tempering treatment to maintain toughness.
The iron-based alloy achieves higher operating temperatures, reduces material costs, and enables faster machining, expanding the application range and increasing machine power without external cooling.
Abstract
Description
[0001] The invention relates to a nickel-iron alloy, a raw part and / or component made from this alloy.
[0002] Depending on the application conditions, rotor forging discs have so far been manufactured from various forged steels.
[0003] NiCrMoV is used for compressor discs and CrMoWVNbN for turbine discs.
[0004] The choice of forging material depends on the application conditions and design requirements.
[0005] When selecting the forging material, it is always important to ensure a balance between strength and toughness in order to meet the design requirements.
[0006] The iron-based material with the highest operating temperature is currently a martensite.
[0007] There is currently no solution for higher operating temperatures.
[0008] There are considerations to switch to nickel-based discs.
[0009] Theoretically, these should allow operating temperatures greater than 923K.
[0010] However, nickel (Ni) components have the following disadvantages, which is why their use is being discussed: - very high costs compared to a steel disc, - longer processing times in manufacturing.
[0011] It is therefore the purpose of the invention to solve the problem mentioned above.
[0012] The problem is solved by an alloy according to claim 1, as well as a component or a blank according to claim 12.
[0013] The dependent claims list further advantageous measures which can be combined arbitrarily to achieve further advantages.
[0014] The description only presents exemplary embodiments of the invention.
[0015] The validation of an austenitic steel showed its basic applicability for higher application temperatures.
[0016] In principle, the chemistry and heat treatment are sufficient to withstand the challenges of a forged component for use in energy generation plants at temperatures greater than 873K.
[0017] The iron-based composition is as follows (in wt.%): Carbon (C) 0,02% - 0,06%, Silicon (Si) 0,20% - 0,30%, Manganese (Mn) 0,4% - 0,8, Cobalt (Co) up to 2.0% Chromium (Cr) 14,0% - 18,0%, Nickel (Ni) 35, 0% - 49,0% Titanium (Ti) 1,8% - 3,0%, Aluminum (Al) 2,2% - 3,5%, Boron (B) 0,002% - 0,010%, Iron (Fe), optionally molybdenum (Mo) 2,7% - 3,3%, Zircon (Zr) up to 0.2%.
[0018] In particular, the alloy consists of these elements.
[0019] Chromium (Cr) strongly promotes the formation of the sigma phase. Chromium (Cr) is also required as an oxidation inhibitor.
[0020] Cobalt (Co) improves solution annealing and contributes to solid solution hardening.
[0021] Molybdenum (Mo) promotes the formation of Laves and TCP phases. Molybdenum (Mo) can also improve oxidation properties and contributes to the solid solution hardening of the austenite phase.
[0022] Manganese (Mn), silicon (Si), and vanadium (V) promote the formation of TCP phases and reduce the gamma prime phase. Manganese (Mn) improves oxidation resistance in high iron environments.
[0023] Wolfram (W) promotes the formation of the Laves phases.
[0024] Carbon (C), boron (B) and zirconium (Zr) contribute to grain boundary strength.
[0025] The background is as follows: a) Corrosion resistance
[0026] By adjusting the chromium content to 14% to 17% by weight, resistance to HTK2 is increased. This is to ensure the formation of a stable Cr2O3 layer with a sufficiently high chromium (Cr) reservoir.
[0027] Simultaneously, increasing the molybdenum (Mo) content can preferably enhance corrosion resistance to chlorine-containing media under high-temperature corrosion conditions. The effect of molybdenum (Mo) and chromium (Cr) is not limited to high-temperature applications alone, but would also provide increased corrosion protection for marine applications. b) Notch embrittlement
[0028] Increasing the chromium and molybdenum content leads to an increase in strength. This is desirable on the one hand. On the other hand, the choice of tempering conditions must be carefully considered to ensure that the risk of notch embrittlement is low and sufficient toughness is maintained.
[0029] Preferably, a 2- or 3-stage QHT tempering treatment is used.
[0030] Advantages besides its primary use as a forged component in energy generation plants): • Expansion of the application range of “cheap” iron-based alloys compared to “expensive nickel-based materials”. • Faster machining of rotor components made from iron compared to nickel-based materials. • Experience gained from the design, manufacturing, and production of high-alloy iron-based alloys can largely be applied. This is particularly helpful for all probabilistic approaches. • The application temperature can be increased, thus enabling an increase in the machine's power and performance without the need for external cooling.
[0031] Examples of the iron-based (Fe) material are: (e.g. C 0.03% means e.g. 0.03 wt.% carbon (C)): - Alloy A: C 0.03%, Si 0.25%, Mn 0.6%, Co 9%, Cr 15%, Ni 40%, Ti 2%, Al 2%, B 0.005%, Nb 2% - Alloy B: C 0.02%, Si 0.3%, Mn 0.5%, Co 7%, Cr 16%, Ni 45%, Ti 2.5%, Al 3%, B 0.006%, Nb 1% - Alloy C: C 0.03%, Si 0.25%, Mn 0.6%, Cr 16%, Ni 43%, Ti 2.0%, Al 2.4%, B 0.003% - Legierung F: C 0.03%, Si 0.2%, Mn 0.6%, Co 8%, Cr 16%, Ni 48%, Ti 2.2%, Al 3.2%, B 0.007%, Mo 2.8%, Nb 2.8%; - Legierung G: C 0.02%, Si 0.25%, Mn 0.7%, Co 6%, Cr 14.5%, Ni 52%, Ti 2.8%, Al 3.1%, B 0.004%, Mo 2.3%, Nb 2.3%; - Legierung H: C 0.04%, Si 0.3%, Mn 0.5%, Co 10%, Cr 17%, Ni 36%, Ti 1.5%, Al 3.5%, B 0.006%, Mo 1.8%, Nb 1.8%; - Legierung I: C 0.03%, Si 0.25%, Mn 0.6%, Cr 16%, Ni 40%, Ti 2.7%, Al 3.0%, B 0.003%, Col,7 - Legierung J: C 0.01%, Si 0.25%, Mn 0.4%, Co 9%, Cr 16%, Ni 40%, Ti 2.5%, Al 3.6%, B 0.002%, Mo 2%, Nb 2%; - Legierung K: C 0.03%, Si 0.3%, Mn 0.6%, Co 7%, Cr 14%, Ni 45%, Ti 2%, Al 3.5%, B 0.005%, Mo 1.5%, Nb 3.2%; - Legierung N: C 0.03%, Si 0.2%, Mn 0.6%, Co 8%, Cr 16%, Ni 48%, Ti 2.2%, Al 3.2%, B 0.007%, Mo 2.8%, Nb 2.8% - O: C 0.03%, Si 0.25%, Mn 0.6%, Cr 16%, Ni 37%, Ti 2.4%, Al 2.9%, B 0.003%, Co 1.4%, Mo 3.0% - Legierung P: C 0.04%, Si 0.3%, Mn 0.5%, Co 10%, Cr 17%, Ni 36%, Ti 1.5%, Al 3.5%, B 0.006%, Mo 1.8%, Nb 1.8% - Legierung R: C 0.01%, Si 0.25%, Mn 0.4%, Co 9%, Cr 16%, Ni 40%, Ti 2.5%, Al 3.6%, B 0.002%, Nb 2% - Legierung S: C 0.03%, Si 0.3%, Mn 0.6%, Co 7%, Cr 14%, Ni 45%, Ti 2%, Al 3.5%, B 0.005%, Mo 1.5%, Nb 3.2%; - Legierung T: C 0.03%, Si 0.25%, Mn 0.6%, Cr 16%, Ni 47%, Ti 2.2%, Al 3.3%, B 0.003% - Legierung V: C 0.03%, Si 0.2%, Mn 0.6%, Co 8%, Cr 16%, Ni 48%, Ti 2.2%, Al 3.2%, B 0.007%, Mo 2.8%, Nb 2.8%;