How Corrosion Occurs and What Influences It
Corrosion is the degradation of metals caused by exposure to environmental conditions. It may result from chemical, electrochemical, or mechanical influences. To correctly interpret corrosion resistance tables, it is essential to understand which specific conditions accelerate or decelerate this process.
Key Factors Affecting the Rate of Corrosion
- Chemical Composition of the Environment
The primary parameters include acidity (pH), presence of salts, and dissolved oxygen content. Aggressive acidic environments and high salt concentrations significantly accelerate metal degradation. - Temperature
Increased temperature generally speeds up corrosion reactions due to enhanced molecular and ionic activity in the aggressive medium. - Flow Rate of the Medium
Under conditions of strong fluid movement, especially turbulence, erosion-corrosion may occur—where metal is further degraded by the mechanical impact of particles and fluid flows. - Mechanical Stresses
Constant or cyclic loads can lead to stress corrosion cracking—microcracks that rapidly propagate under corrosive conditions. - Protective Measures
These include applying coatings, forming a passive layer (e.g., on stainless steel), and using chemical inhibitors that slow or fully block corrosion reactions.
Table: Corrosion Resistance of Metals and Alloys Under Normal Conditions
| Seredovishche | Aluminum | Brass | Cast iron and carbon steel | Stainless steel | Alloy | Titanium | |||
| 416 and 440C | 304 (08Х18Н10) | 316 (03Х17Н14М3) | 254 SMO | C276 | |||||
| Acetaldehyde | A | A | C | A | A | A | A | A | A |
| Acetic acid | C | C | C | C | C | A | A | A | A |
| Acetone | B | A | A | A | A | A | A | A | A |
| Acetylene | A | A | A | A | A | A | A | A | A |
| Alcohols | A | A | A | A | A | A | A | A | A |
| Aluminum sulfate | C | C | C | C | A | A | A | A | A |
| Ammonia | A | C | A | A | A | A | A | A | A |
| Naxate | C | C | C | C | C | B | A | A | A |
| Caustic ammonia | A | C | A | A | A | A | A | A | A |
| Ammonium nitrate | B | C | B | B | A | A | A | A | C |
| Ammonium phosphate | B | B | C | B | A | A | A | A | A |
| Ammonium sulphate | C | C | C | C | B | A | A | A | A |
| Ammonium sulfite | C | C | C | C | A | A | A | A | A |
| Aniline | C | C | C | C | A | A | A | A | A |
| Asphalt, bitumen | A | A | A | A | A | A | A | A | A |
| Beer | A | A | B | B | A | A | A | A | A |
| Benzene | A | A | A | A | A | A | A | A | A |
| Benzoic acid | A | A | C | C | A | A | A | A | A |
| Boric acid | C | B | C | C | A | A | A | A | A |
| Bromine dry | C | C | C | C | B | B | A | A | C |
| Bromine wet | C | C | C | C | C | C | C | A | C |
| Bhutan | A | A | A | A | A | A | A | A | A |
| Calcium chloride | C | C | B | C | B | B | A | A | A |
| Calcium hypochlorite | C | C | C | C | C | C | A | A | A |
| Carbon dioxide dry | A | A | A | A | A | A | A | A | A |
| Carbon dioxide vl | A | B | C | C | A | A | A | A | A |
| Carbon disulfide | C | C | A | B | A | A | A | A | A |
| Carbonic acid | A | B | C | C | A | A | A | A | A |
| Carbon tetrachloride | A | A | B | B | A | A | A | A | A |
| Chlorine dry | C | C | A | C | B | B | A | A | C |
| Chlorine wet | C | C | C | C | C | C | C | B | A |
| Chromic acid | C | C | C | C | C | C | A | A | A |
| Citric acid | B | C | C | C | B | A | A | A | A |
| Coke acid | C | B | A | A | A | A | A | A | A |
| Copper sulphate | C | C | C | C | C | B | A | A | A |
| Cotton oil | A | A | A | A | A | A | A | A | A |
| creosote | C | C | A | A | A | A | A | A | A |
| Dowtherm | A | A | A | A | A | A | A | A | A |
| Ethane | A | A | A | A | A | A | A | A | A |
| Ether | A | A | B | A | A | A | A | A | A |
| Ethyl chloride | C | B | C | C | B | B | A | A | A |
| Ethylene | A | A | A | A | A | A | A | A | A |
| Ethylene glycol | A | A | A | A | A | A | A | A | A |
| Ferric chloride | C | C | C | C | C | C | B | A | A |
| Fluorine dry | B | B | A | C | B | B | A | A | C |
| Fluoride wet | C | C | C | C | C | C | C | B | C |
| Formaldehyde | A | A | B | A | A | A | A | A | A |
| Formic acid | B | C | C | C | C | B | A | A | C |
| Freon wet | C | C | B | C | B | A | A | A | A |
| Freon dry | A | A | B | A | A | A | A | A | A |
| Furfural | A | A | A | B | A | A | A | A | A |
| Gasoline is stable | A | A | A | A | A | A | A | A | A |
| Glucose | A | A | A | A | A | A | A | A | A |
| Hydrochloric acid | C | C | C | C | C | C | C | B | С |
| Hydrofluoric acid | C | C | C | C | C | C | C | B | С |
| Hydrogen | A | A | A | C | A | A | A | A | С |
| Hydrogen Peroxide | A | C | C | C | A | A | A | A | A |
| Hydrogen sulphide | C | C | C | C | A | A | A | A | A |
| Iodine | C | C | C | C | A | A | A | A | С |
| Magnesium hydroxide | B | B | A | A | A | A | A | A | A |
| Mercury | C | C | A | A | A | A | A | A | С |
| Methanol | A | A | A | A | A | A | A | A | A |
| Methyl ethyl glycol | A | A | A | A | A | A | A | A | A |
| Milk | A | A | C | A | A | A | A | A | A |
| Natural gas | A | A | A | A | A | A | A | A | A |
| Nitric acid | C | C | C | C | A | A | A | B | A |
| Oleic acid | C | C | C | B | B | A | A | A | A |
| Oxalic acid | C | C | C | C | B | B | A | A | С |
| Oxygen | C | A | C | C | B | B | B | B | С |
| Mineral oil | A | A | A | A | A | A | A | A | |
| Phosphoric acid | C | C | C | C | A | A | A | A | С |
| Picric acid | C | C | C | C | B | A | A | A | A |
| Potassium carbonate | C | C | B | B | A | A | A | A | A |
| Potassium chloride | C | C | B | C | B | B | A | A | A |
| Potassium hydroxide | C | C | B | B | A | A | A | A | A |
| Propane | A | A | A | A | A | A | A | A | A |
| Rosin, resin | A | A | B | A | A | A | A | A | A |
| Silver nitrate | C | C | C | C | A | A | A | A | A |
| Sodium acetate | A | A | A | A | A | A | A | A | A |
| Sodium carbonate | C | C | A | B | A | A | A | A | A |
| Sodium chloride | С | A | C | C | B | B | A | A | A |
| Sodium hydroxide | С | С | A | B | B | A | A | A | A |
| Sodium hypochlorite | C | C | C | C | C | C | C | A | A |
| Sodium thiosulfate | C | C | C | C | B | A | A | A | A |
| Tin chloride | C | C | C | C | C | B | A | A | A |
| Water vapor | A | A | A | A | A | A | A | A | A |
| Stearic acid | C | B | B | B | A | A | A | A | A |
| Sulphur | A | B | A | A | A | A | A | A | A |
| Sulphur dioxide dry | C | C | C | C | C | B | A | A | A |
| Sulphur trioxide dry | C | C | C | C | C | B | A | A | A |
| Sulfuric acid | C | C | C | C | C | C | A | A | С |
| Sulfuric acid | C | C | C | C | B | B | A | A | A |
| tar | A | A | A | A | A | A | A | A | A |
| Trichloroethylene | B | B | B | B | B | A | A | A | A |
| Turpentine | A | A | B | A | A | A | A | A | A |
| Vinegar | B | B | C | C | A | A | A | A | A |
| Chemically treated water | A | A | A | A | A | A | A | A | A |
| Distilled water | A | A | C | C | A | A | A | A | A |
| Sea water | С | A | C | C | C | B | A | A | A |
| Whiskey, vodka, wine | A | A | C | C | A | A | A | A | A |
| Zinc chloride | C | C | C | C | C | C | B | A | A |
| Zinc sulfate | С | С | С | С | А | А | А | А | А |
This table shows the resistance of various metals to specific environmental exposures. Please note that resistance is also influenced by concentration, temperature, pressure, and other parameters.
Legend: A – Generally non-corrosive, B – Minimal to slight corrosion, C – Not suitable
Extended corrosion performance table
| Material | Application Areas | Medium | Corrosion Rate, mm/year | Recommended Inhibitors | Temperature Range, °C |
|---|---|---|---|---|---|
| Stainless Steel 304 | DHW systems, food industry, ITP | Fresh water | 0.02–0.1 | NaNO₂, nitrites | –50 … +300 |
| Stainless Steel 316L | Chemical plants | Acidic solutions (pH<3) | 0.1–0.5 | Phosphates, silicates | –50 … +400 |
| Titanium Gr2 | Seawater, acids | Seawater | 0.005–0.02 | Rarely required | –200 … +350 |
| Super Duplex 2507 | Chlorides, seawater | Pumping stations | 0.01–0.05 | Molybdates | –50 … +300 |
| Graphite Composite | Aggressive acids | Sulphuric acid 10% | 0.005–0.02 | Not required | 0 … +150 |
| Grey Cast Iron | Mineral water | Water with CO₂ | 0.1–0.3 | Phosphates | 0 … +120 |
Note:
– Corrosion rates are provided as indicative ranges based on standard laboratory tests.
– Recommended inhibitors significantly reduce degradation during operational use.
Standards and Regulatory Documents
Accurate assessment of corrosion resistance, testing procedures, and protection strategies must rely on recognized international and national standards. The following documents are widely used in industrial and scientific practices related to metal corrosion:
- DSTU EN ISO 9022 — “Optics and optical instruments – Environmental test methods”
Adapted in Ukraine from ISO 9022, this standard defines testing methods for materials and products under environmental influences. It emphasizes simulating operational conditions and assessing corrosion resistance under various temperature and humidity regimes, salt spray exposure, and polluted or aggressive gases. - ASTM G31 — “Standard Guide for Laboratory Immersion Corrosion Testing of Metals”
One of the most commonly used global standards for determining corrosion rates through immersion testing. It details sample preparation, selection of corrosive media, test parameters (temperature, concentration, exposure time), and methods for calculating average corrosion rates. Widely used for comparing alloy performance. - API 571 — “Damage Mechanisms Affecting Fixed Equipment in the Refining Industry”
A guide from the American Petroleum Institute providing comprehensive information on damage mechanisms, including various corrosion and erosion forms observed in petrochemical and refining industries. It covers over 60 damage types, such as wet H₂S corrosion, stress corrosion cracking (SCC), chloride-induced corrosion, and more. Essential for inspections, residual life assessments, and maintenance planning.
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Last Updated on by Микола Фролкин
