| 介绍 | Austenitic stainless steel
Type X5CrNi18-10 stainless steel
EN 1.4301, AISI 304
Applications
- These are the most commonly used stainless steels, those resistant against corrosion is utilized e.g. in chemical, paper and food industry. These steels are also popular in household wares, architecture and transportation.
- Can be used at low temperatures down to -196°C even as welded structures.
- Moderate strengths can be reached at elevated temperatures (~550°C). Temperatures for excessive scaling are close to 850°C.
Welding
- Weldability is good. The thermal expansion is 1,5-times larger compared with carbon steels.
- Chromium and nickel contents of the filler metal have to match or to be higher than the composition of the base metal, e.g. type 19-9.
- In welded plates with wall thickness exceeding 6 mm, steels with low carbon content (1.4307, AISI 304L) or (1.4541, AISI 321) are recommended.
- Cleaning the weld seam has a significant importance for corrosion resistance. Pickling is recommended.
Forming and machining
- Formability is good, thus forces needed and the elastic return is bigger compared with carbon steels.
- Because of a high ductility and a strong work hardening it is recommended to use sharp tools, an effective cooling and adequate feed of tool.
- Higher austenite stability and a lower work hardening rate can be achieved by an increase of nickel and some other alloying elements.
Corrosion resistance
- Resistance to atmospheric corrosion is adequate for several applications. Special attention should be paid on surface finish and regular cleaning procedures in marine and industrial environments.
- These steels have a good resistance against oxidizing acids. Corrosion resistance in non-oxidazing acids like sulphuric acid, hydrofluoric acid and hydrochloride acid is limited.
- Can be used e.g. in the following chemically pure, boiling solutions: acetic acid (=5%), acetone, ammonia, ammonia sulphate, benzene, benzene, citric acid (=10%), copper sulphate, ethanol, ethylic ether, formaldehyde, fruit juice, HNO 3 (=45%), lactic acid (=10%), NaOH (=30%), Na 2 SO 3 (=50%), oil, phosphoric acid (=20%), potassium- and sodium-carbonate, tartaric acid (=15%), toluene, wine (when SO 2 used for preservation grade 1.4404, AISI 316L or 1.4432 is recommended), xylene and yeast.
- In chloride containing solutions pitting and crevice corrosion is possible depending on various parameters like chloride concentration, temperature, pH value, redox potential, crevice geometry and others. For instance in drinking water supply systems chloride concentration up to 200 mg/l are usually tolerable.
- When the temperature of chloride containing solutions exceeds 50°C and the construction is loaded, stress corrosion cracking is possible.
- The best material performance is reached usually with the help of adequate design, correct post-weld treatment and regular cleaning during use (if applicable).
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