Selection of corrosion-resistant alloy materials

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General characteristics of nitric acid (HNO3): It is an oxidizing medium. The operating temperature for concentrated HNO₃ is generally below 40°C. Elements Cr and Si contribute to oxidation resistance; therefore, stainless steels and other materials containing Cr and Si are ideal corrosion-resistant materials for concentrated HNO₃. High-silicon cast iron (STSi15R): all temperatures below 93% ； High-chromium cast iron (Cr28): all temperatures below 80% ； Stainless steel (SUS304, SUS316, SUS316L): All temperatures below 80% ； S-05 steel (0Cr13Ni7Si4): all temperatures below 98% ； Industrial pure titanium (TA1, TA2): All temperatures below the boiling point (except in cases of fuming) ； Industrial pure aluminum (Al): All temperatures at room temperature (used only for containers) ； CD-4MCu age-hardening alloy: all temperatures below the boiling point ； Inconel, Hastelloy C, gold, tantalum, etc. all exhibit good corrosion resistance. General properties of sulfuric acid (H₂SO₄): The boiling point increases as the concentration rises. For example: at a concentration of 5%, the boiling point is 101 ℃ ； At a concentration of 50%, its boiling point is 124℃ ； The concentration is 98%, and its boiling point is 332°C. At concentrations below 75%, it is reductive (or neutral); above 75%, it is oxidative. Stainless steel (SUS316, SUS316L): below 40 °C temperature, around 20% concentration ； 904 steel (SUS904, SUS904L): Suitable for temperatures of 40–60 °C and concentrations of 20–75% ； Temperature: 80 °C; concentration: below 60% ； High-silicon cast iron (STSi15R): various concentrations from room temperature to 90 °C ； Pure lead, hard lead: various temperatures at room temperature ； S-05 steel (0Cr13Ni7Si4): concentrated sulfuric acid at temperatures below 90 °C, and high-temperature concentrated sulfuric acid (120–150 °C) ； Ordinary carbon steel: concentrated sulfuric acid at over 70% at room temperature ； Cast iron: Concentrated sulfuric acid at room temperature ； Monel, metallic nickel, Inconel: sulfuric acid at moderate temperature and concentration ； Titanium-molybdenum alloy (Ti-32Mo): below boiling point, in 60% sulfuric acid and below 50 °C in 98% sulfuric acid ； Hastelloy B, D: below 100 °C, 75% sulfuric acid ； Hastelloy C: Various temperatures around 100 °C ； Nickel cast iron (STNiCr202): Sulfuric acid at 60–90% concentration at room temperature. General properties of hydrochloric acid (HCl): It is a reducing medium, with a maximum temperature of 36–37%. Boiling point: At a concentration of 20%, it is 110 ℃ ； When the concentration is between 20% and 36%, it is 50℃ ； Therefore, the maximum temperature for hydrochloric acid is 50 °C. Metallic tantalum (Ta): It is the most ideal material for resisting corrosion in hydrochloric acid, but it is expensive and is often used in measuring devices where precision is required ； Hastelloy B: hydrochloric acid at a temperature of ≤50 ℃ and a concentration of 36% ； Titanium-molybdenum alloy (Ti-32Mo): all temperatures and all concentrations ； Nickel-molybdenum alloy (Chlorimetz, 0Ni62Mo32Fe3): all temperatures and all concentrations ； Industrial pure titanium (TA1, TA2): hydrochloric acid at 10% or less at room temperature ； ZXSNM(L) alloy (00Ni70Mo28Fe2): hydrochloric acid at 50 °C and 36% concentration ； Phosphoric acid (H3PO4): The concentration of phosphoric acid is generally 30–40%, and the temperature is 80–90 °C. Phosphoric acid often contains H2SO4, fluoride ions, chloride ions, silicates, etc. Stainless steel (SUS316, SUS316L): Boiling phosphoric acid with a concentration of 85% or less ； Durimet20 (Alloy No. 20): A corrosion- and wear-resistant alloy with a concentration of 85% or less, at temperatures below its boiling point ； CD-4Mcu: Age-hardening alloy, corrosion- and wear-resistant alloy ； High-silicon cast iron (STSi15R), high-chromium cast iron (Cr28): suitable for nitric acid at various concentrations below its boiling point ； 904, 904L: Nitric acid at various concentrations below the boiling point ； Incolloy825: Nitric acid at various concentrations below its boiling point. General characteristics of hydrofluoric acid (HF): Hydrofluoric acid is highly toxic. High-silicon cast irons, ceramics, and glass are generally resistant to most acids, but hydrofluoric acid corrodes them. Magnesium (Mg): An ideal corrosion-resistant material for hydrofluoric acid, generally used only for containers ； Titanium: Suitable for concentrations of 60–100% (at room temperature); the corrosion rate increases at concentrations below 60% ； Monel alloy: It is an excellent material resistant to hydrofluoric acid, and it can withstand all temperatures and all concentrations (including the boiling point) ； Silver (Ag): Boiling hydrofluoric acid, commonly used in metering devices. General characteristics of caustic soda (NaOH): The corrosiveness of caustic soda increases as the temperature rises. SUS304, SUS304L, SUS316, SUS316L: concentration 42%, room temperature to 100 ℃ ； Nickel cast iron (STNiCr202): concentration below 40%, temperature below 100 ℃ ； Incolloy804, 825: Concentration (NaOH+NaCl) of 42% can reach 150 ℃ ； Pure nickel: The concentration of (NaOH+NaCl) can reach 150 at 42% ℃ ； Monel alloy: high temperatures and high concentrations of caustic soda. The alkali (Na2CO3) soda ash mother liquor contains 20–26% NaCl, 78% Cl2, and 2–5% CO2, with a temperature range of 32–70 °C. High-silicon cast iron: suitable for soda ash at temperatures of 32–70 °C and concentrations of 20–26% ； Industrial pure titanium: At present, several large soda ash plants in China use titanium pumps made of titanium for handling mediums such as mother liquor. Petrochemical, pharmaceutical, food industries, etc. Oil: 0Cr13, 1Cr13, 1Cr17 ； Petrochemical industry: 1Cr18Ni9(304), 1Cr18Ni12Mo2Ti(SUS316) ； Acidic steel: 904, 904L ； Vinegar Acid: Titanium (Ti), 316L ； Medicine: high-silicon cast iron, SUS316, SUS316L ； Materials: 1Cr18Ni9, 0Cr13, 1CR13 ；