Crevice corrosion of 316 stainless steel in desalination

SAE 316L grade

stainless steel Stainless steel, also known as inox, corrosion-resistant steel (CRES), or rustless steel, is an iron-based alloy that contains chromium, making it resistant to rust and corrosion. Stainless steel's resistance to corrosion comes from its chromi ...

, sometimes referred to as A4 stainless steel or marine grade stainless steel, is the second most common

austenitic stainless steel Austenitic stainless steel is one of the five families of stainless steel (along with ferritic, martensitic, duplex and precipitation hardened). Its primary crystalline structure is austenite (face-centered cubic). Such steels are not hardena ...

after 304/A2 stainless steel. Its primary alloying constituents after

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

, are

chromium Chromium is a chemical element; it has Symbol (chemistry), symbol Cr and atomic number 24. It is the first element in Group 6 element, group 6. It is a steely-grey, Luster (mineralogy), lustrous, hard, and brittle transition metal. Chromium ...

(between 16–18%),

nickel Nickel is a chemical element; it has symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive, but large pieces are slo ...

(10–12%) and

molybdenum Molybdenum is a chemical element; it has Symbol (chemistry), symbol Mo (from Neo-Latin ''molybdaenum'') and atomic number 42. The name derived from Ancient Greek ', meaning lead, since its ores were confused with lead ores. Molybdenum minerals hav ...

(2–3%), up to 2%

manganese Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...

, with small (<1%) quantities of silicon, phosphorus & sulfur also present. The addition of molybdenum provides greater corrosion resistance than 304, with respect to localized corrosive attack by

chloride The term chloride refers to a compound or molecule that contains either a chlorine anion (), which is a negatively charged chlorine atom, or a non-charged chlorine atom covalently bonded to the rest of the molecule by a single bond (). The pr ...

s and to general corrosion by reducing acids, and other acids such as

sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, ...

; while sulfur is added to improve ease-of-tooling/machinability. 316L grade is the low carbon version of 316 stainless steel, which improves relative corrosion-resistance. When cold worked, 316 can produce high yield and tensile strengths similar to Duplex stainless grades. It is commonly used in chemical and

petrochemical Petrochemicals (sometimes abbreviated as petchems) are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable s ...

industry, in

food processing Food processing is the transformation of agricultural products into food, or of one form of food into other forms. Food processing takes many forms, from grinding grain into raw flour, home cooking, and complex industrial methods used in the mak ...

pharmaceutical Medication (also called medicament, medicine, pharmaceutical drug, medicinal product, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy ( pharmacotherapy) is an important part of the ...

equipment,

medical devices A medical device is any device intended to be used for medical purposes. Significant potential for hazards are inherent when using a device for medical purposes and thus medical devices must be proved safe and effective with reasonable assura ...

jewellery Jewellery (or jewelry in American English) consists of decorative items worn for personal adornment such as brooches, ring (jewellery), rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the ...

, luxury watches (especially diver's watches), in

potable water Drinking water or potable water is water that is safe for ingestion, either when drunk directly in liquid form or consumed indirectly through food preparation. It is often (but not always) supplied through taps, in which case it is also calle ...

piping,

wastewater Wastewater (or waste water) is water generated after the use of freshwater, raw water, drinking water or saline water in a variety of deliberate applications or processes. Another definition of wastewater is "Used water from any combination of do ...

treatment, in marine applications and architectural applications near the seashore or in urban areas.

Gallery

File:External Thread Galling.png, Pipe fitting of 316 steel (equivalent to A4 steel) File:Schmidt K5 fountain pen converter + 2.5 mm 316 Stainless Steel bearing ball.jpg, A fountain pen converter containing a 316 stainless ball of 2.5 mm diameter File:Orbital Welding 316L Stainless Steel.jpg, Two welded 316L steel pipes. File:316L Stainless Steel Unpolished.jpg, Unpolished 316L steel. File:SCC_of_stainless_steel_UNS_S31603.jpg, Stress corrosion cracking in 316L by synthetic seawater File:Laserengravingonsteel.jpg, Hose barb pipe fitting in 316L File:Citizen Diver's 200m Eco Drive - Diving watch.jpg,

Citizen Citizenship is a membership and allegiance to a sovereign state. Though citizenship is often conflated with nationality in today's English-speaking world, international law does not usually use the term ''citizenship'' to refer to nationality ...

watch in 316L on a rubber strap

References

{{SAE International Stainless steel

Gallery

See also

References