فهرست مطالب
In the complex world of industrial material selection, choosing the right alloy is a critical decision that balances performance, cost, and longevity. From the ubiquitous stainless steels to the high-performance nickel-based superalloys, each material offers a unique set of properties tailored for specific challenges. This guide provides a clear and concise comparison of key alloys—including various stainless steels, Hastelloy, Monel, Inconel, Incoloy, copper-nickel, and pure nickel—highlighting their core strengths and typical applications to inform your decision-making process for different corrosive environments and mechanical demands.
Overview of Corrosion-Resistant Alloys
| نام آلیاژ | General Classification | Core Advantage | Typical Application Scenarios |
| 316/316L | فولاد ضد زنگ آستنیتی | Low cost, good versatility, excellent manufacturability | General chemical containers, food equipment, architectural facades, medical implants |
| Duplex (2205) | فولاد ضد زنگ دوبلکس | Extremely high strength, resistance to chloride stress corrosion cracking, cost-effective | Offshore platform pipelines, chemical tanker tanks, pulp mills, pressure vessels |
| Nickel 200/201 | Commercially Pure Nickel | Resistance to caustic alkalis (NaOH), excellent mechanical properties at high temperatures, high thermal/electrical conductivity | Caustic alkali evaporators, electronic components, food processing equipment, synthetic fiber production |
| مونل 400 | Nickel-Copper Alloy | Resistance to seawater and reducing acids (especially HF), high strength | Marine engineering (pump shafts, valve cores), hydrofluoric acid equipment, crude oil distillation columns |
| اینکونل 600 | Nickel-Chromium-Iron Alloy | Resistance to high-temperature oxidation, carburization resistance, stress corrosion cracking resistance | Heat treatment furnace parts, heating element sheaths, nuclear power plant steam generator tubing |
| Incoloy 800/800H | Iron-Nickel-Chromium Alloy | High-temperature strength/creep resistance, oxidation and carburization resistance | Heat exchangers, annealing furnace covers, ethylene cracking furnace tubes |
| اینکونل 625 | Nickel-Chromium-Molybdenum Alloy | High strength, excellent pitting/crevice corrosion resistance, easy welding | Marine engineering, aerospace (engine components), chemical reactors, flue gas desulfurization (FGD) systems |
| هاستلوی C276 | Nickel-Chromium-Molybdenum Alloy | “Universal” extreme corrosion resistance (reducing/oxidizing media) | Most demanding chemical environments (strong acids with Cl竅ｻ, H竄４, F竅ｻ), waste incineration, pharmaceuticals |
| Cu-Ni (70/30, 90/10) | آلیاژ مس نیکل | Seawater corrosion resistance/fouling resistance, excellent thermal conductivity | Seawater desalination pipelines, ship seawater pipelines, offshore platform cooling systems |
Stainless Steel Family (Stainless Steels)
316/316L Stainless Steel:
- Positioning: Economical and practical “all-rounder”. The most widely used stainless steel in industry.
- برنامه های کاربردی: Food processing equipment, pharmaceutical equipment, general chemical containers, architectural facades, surgical implants. Performs well in mild corrosive environments.
- محدودیتها: Susceptible to pitting and stress corrosion cracking (SCC) caused by chloride ions.
Duplex Stainless Steel (e.g., 2205, 2507):
- Positioning: High-strength, high-corrosion resistance upgrade to 316L. The austenite+ferrite duplex structure gives it ultra-high strength and excellent resistance to chloride SCC.
- برنامه های کاربردی: Offshore oil and gas (pipelines, pressure vessels), chemical tanker cargo tanks, pulp mill digesters, high-strength structural components.
- محدودیتها: May precipitate brittle phases at high temperatures (>300°C), unsuitable for very high-temperature applications; not corrosion-resistant in strong reducing acids (e.g., hydrochloric acid).
Commercially Pure Nickel & Nickel-Copper Alloys
Nickel 200 (commercially pure nickel, >99%) / Nickel 201 (low carbon version):
- Positioning: Expert in resisting caustic alkalis. Has unparalleled resistance to high-temperature, high-concentration sodium hydroxide (NaOH) and molten alkalis.
- برنامه های کاربردی: Caustic soda (lye) evaporators, electronic components, food processing equipment (resists organic acids), synthetic fiber production equipment.
- خصوصیات: Ferromagnetic, good electrical and thermal conductivity.
Monel 400 (~66% Ni, ~33% Cu):
- Positioning: King of marine environments and hydrofluoric acid (HF). Inherits the dual advantages of nickel’s resistance to reducing media and copper’s resistance to reducing media; high strength, strong work hardening tendency.
- برنامه های کاربردی: Marine engineering (pump shafts, propellers, valve cores, seawater pipelines), hydrofluoric acid production and storage equipment, crude oil distillation columns, gasoline storage tanks.
- خصوصیات: Excellent corrosion resistance to fast-flowing seawater.
Nickel-Chromium-Iron Family (Nickel-Chromium-Iron)
This family of alloys gains resistance to oxidizing media and high-temperature oxidation by adding chromium.
Inconel 600 (~76% Ni, 15% Cr, 8% Fe):
- Positioning: Excellent resistance to high-temperature oxidation and carburization, along with good stress corrosion cracking resistance.
- برنامه های کاربردی: Heat treatment industry (furnace rollers, retorts, radiant tubes), electronic heat exchangers, nuclear power plant steam generator tubing, nitric acid production equipment.
Incoloy 800 (~32% Ni, 21% Cr, balance Fe) / 800H (high-temperature version):
- Positioning: High-temperature material between stainless steel and nickel-based alloys. High iron content, relatively low cost, good high-temperature strength and creep resistance.
- برنامه های کاربردی: Heat exchangers, heater tubes, annealing furnace covers, ethylene cracking furnace tubes (core application).
High-Performance Nickel-Chromium-Molybdenum Family (High-Performance Ni-Cr-Mo Alloys)
This family gains top-tier resistance to pitting, crevice corrosion, and general corrosion by adding large amounts of Molybdenum (Mo).
Inconel 625 (~58% Ni, 21% Cr, 9% Mo, with Nb):
- Positioning: Perfect combination of strength and corrosion resistance. Strengthened by molybdenum and niobium (Nb), making it very high strength with excellent weldability.
- برنامه های کاربردی: Aerospace (engine exhaust sections, honeycomb seals), marine engineering (propellers, submarine components), chemical reactors, hydrometallurgy, flue gas desulfurization (FGD) systems.
Hastelloy C276 (~57% Ni, 16% Cr, 16% Mo, with W):
- Positioning: The “ultimate weapon” for tackling the most苛刻 (kēkè – harsh/demanding) corrosive environments. Among all alloys, its resistance to general corrosion is top-ranked, especially in reducing media.
- برنامه های کاربردی: Chemical process industry (strong acid environments with chloride ions, fluoride ions), wet chlorine gas, waste incinerators, pharmaceutical industry API production equipment, sour gas fields (high H₂S/CO₂).
Copper-Nickel Alloys (Copper-Nickel Alloys)
Cu-Ni 90/10 (90% Cu, 10% Ni) / 70/30 (70% Cu, 30% Ni):
- Positioning: Experts in seawater systems. Extremely high resistance to seawater corrosion and effectively inhibits marine biofouling (anti-fouling properties).
- برنامه های کاربردی: Seawater desalination plant piping systems, ship seawater cooling lines, offshore platform firefighting systems, heat exchanger tubes.
- خصوصیات: Excellent thermal conductivity, mechanical properties similar to mild steel, easy to process.
How to Choose? A Concise Guide
Consider the Medium:
- Seawater/Marine Environment: Prefer مونل 400 یا Cu-Ni; consider دوبلکس 2205 یا اینکونل 625 (when strength is required).
- Caustic Alkali (NaOH/KOH): Prefer Nickel 200/201.
- Dilute Sulfuric Acid/Hydrochloric Acid (reducing acids): Prefer هاستلوی C276.
- Nitric Acid (oxidizing acid): Stainless steel or اینکونل 600 might suffice.
- Hydrofluoric Acid (HF): Prefer مونل 400.
- Chloride Ion Environment: Avoid 316L, choose دوبلکس, اینکونل 625، یا C276 (escalating based on severity).
Consider Temperature:
- < 300°C: Most materials can be considered.
- > 300°C, Oxidizing Atmosphere: Choose اینکونل 600 یا Incoloy 800H.
- Load-bearing components at high temperature: Choose Incoloy 800H (creep resistance).
Consider Mechanical Requirements:
- Need weight reduction/high pressure: Choose دوبلکس (highest strength).
- Need excellent impact toughness: Choose nickel-based alloys (e.g., 625, C276).
Consider Budget:
- Cost-sensitive: Start evaluation with 316 لیتر یا دوبلکس.
- Performance paramount: Directly consider اینکونل 625 یا هاستلوی C276.
The final choice must be based on a comprehensive evaluation of the specific process environment (temperature, pressure, medium composition and concentration), equipment design life, and total project cost, often requiring reference to corrosion data manuals or conducting corrosion tests.
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