ASTM A312 stainless steel

304/304L Stainless Steel

Chemical Composition - Stainless Steel 304/304L

304 Resistance To Corrosion

*Maximum carbon content of 0.04% acceptable for drawn tubes

Typical Mechanical Properties-Stainless Steel 304/304L

The main constituents of 304 stainless steel - other than iron - are Chromium and Nickel.

304 contains 18 - 20% Chromium (Cr). Chromium is the essential chemical in all stainless steel and it is that which forms the thin passive layer that makes the metal "stainless"

304 also contains 8-10.5% Nickel (Ni). This is added to make the Austenitic structure more stable at normal temperatures. 

The nickel also improves high-temperature oxidation resistance makes the steel resistant to stress corrosion cracking.

Where the steel is to be stretched formed a lower percentage (8%) of nickel should be selected. If the steel is to be deep drawn a higher percentage is better (9% or more).

In addition a number of other chemicals may be present but these are expressed as maximum permited levels with the exception of the increased quantity of carbon required in 304H - i.e. a minimum of .04% and a maximum of 0.10%

*Maximum carbon content of 0.04% acceptable for drawn tubes

316/316L Stainless Steel

Type 316/316L Stainless Steel is a molybdenum steel possessing improved resistance to pitting by solutions containing chlorides and other halides.

Chemcial Composition - 316/316L stainless steel tubing and pipe

Typical Mechanical Properties- Stainless Steel 316/316L

Physical Properties - 316/316L/316H stainless steel in the Annealed Condition at -20°F to +100°F

Yield Strength

Design Features - 316/316L Stainless Steel

• Type 316 is more resistant to atmospheric and other mild environments than Type 304.  it is resistant to dilute solutions (i.e. 1-5%) of sulfuric acid up to 120°F.  However, in certain oxidizing acids, Type 316 is less resistant than Type 304.
• 316 is susceptible to carbide precipitation when exposed in the temperature range of 800° - 1500°F and therefore is susceptible to intergranular corrosion in the as-welded condition.  Annealing after welding will restore corrosion resistance.
• Type316L has the same composition as Type 316 except the carbon content is held below 0.03%.  Not unexpectedly, its general corrosion resistance and other properties closely correspond to those of Type 316.  However, it does provide immunity to intergranular attack in the as-welded condition or with short periods of exposure in the temperature range of 800° - 1500°F. The use of 316L is recommended when exposure in the carbide precipitation range is unavoidable and where annealing after welding is not practical.  However, prolonged exposure in this range may embrittle the material and make it susceptible to intergranular attack.
• The maximum temperature for scaling resistance in contnuous services is about 1650°F, and 1500°F for intermittent service.
• May be susceptible to chloride stress corrosion cracking.
• Non-hardenable; non-magnetic in the annealed condition, and slightly magnetic when cold worked.
• Improved corrosion resistance to chlorides.

310S Stainless Steel

310S Stainless Steel has excellent resistance to oxidation under constant temperatures to 2000°F.

Chemical Composition - Stainless Steel 310S

Typical Mechanical Properties- Stainless Steel 310S

Specifications - Stainless Steel 310S

• ASTM: A312, A403, A182
• ASME: SA312, SA403, SA182
  

317L Stainless Steel

317L is a molybdenum bearing austenitic chromium nickel steel similar to type 316, except the alloy content in 317L is somewhat higher.

Chemical Composition - Stainless Steel 317/317L

Typical Mechanical Properties- Stainless Steel 317L

Specifications - Stainless Steel 317L

• ASTM: A312, A403, A182
• ASME: SA312, SA403, SA182
  

321/321H Stainless Steel

Type 321 is basic type 304 modified by adding titanium in an amount at least 5 times the carbon plus nitrogen contents.

Specifications -321/321H Stainless Steel

• ASTM:A312, A403, A182
• ASME: SA312, SA403, SA182

Chemical Composition - 321/321H Stainless steel

*The titanium content shall not be less than 5 times the carbon content and not more than 0.60%.  321H requires the titanium content to be not less than 4 times the carbon content and not more than 0.60%.

Typical Mechanical Properties

410 Stainless Steel

Specifications - Stainless Steel 410

• ASTM: A268, A815, A182

Chemical Composition - Stainless Steel 410

Typical Applications - Stainless Steel 410

• Pipelines transporting fluids mixed with solids like coal, sand or gravel.

Tensile Requirements - Stainless Steel 410

Tensile Strength (KSI): 60

Yield Strength (KSI): 30

Duplex 2205 (UNS S31803)

Duplex 2205 (UNS S31803), or Avesta Sheffield 2205 is a ferritic-austenitic stainless steel.

Specifications - Duplex 2205

• ASTM: A790, A815, A182
• ASME: SA790, SA815, SA182

Chemical Composition - Duplex 2205 

Stainless steels are also classified by their crystalline structure:

• Austenitic stainless steels comprise over 70% of total stainless steel production. They contain a maximum of 0.15% carbon, a minimum of 16% chromium and sufficient nickel and/or manganese to retain an austenitic structure at all temperatures from the cryogenic region to the melting point of the alloy. A typical composition is 18% chromium and 10% nickel, commonly known as 18/10 stainless is often used in flatware. Similarly 18/0 and 18/8 is also available. ¨Superaustenitic〃 stainless steels, such as alloy AL-6XN and 254SMO, exhibit great resistance to chloride pitting and crevice corrosion due to high Molybdenum contents (>6%) and nitrogen additions and the higher nickel content ensures better resistance to stress-corrosion cracking over the 300 series. The higher alloy content of "Superaustenitic" steels means they are fearsomely expensive and similar performance can usually be achieved using duplex steels at much lower cost.
• Ferritic stainless steels are highly corrosion resistant, but far lessdurable than austenitic grades and cannot be hardened by heat treatment. They contain between 10.5% and 27% chromium and very little nickel, if any. Most compositions include molybdenum; some, aluminium or titanium. Common ferritic grades include 18Cr-2Mo, 26Cr-1Mo, 29Cr-4Mo, and 29Cr-4Mo-2Ni.
• Martensitic stainless steels are not as corrosion resistant as the other two classes, but are extremely strong and tough as well as highly machineable, and can be hardened by heat treatment. Martensitic stainless steel contains chromium (12-14%), molybdenum (0.2-1%), no nickel, and about 0.1-1% carbon (giving it more hardness but making the material a bit more brittle). It is quenched and magnetic. It is also known as "series-00" steel.
• Duplex stainless steels have a mixed microstructure of austenite and ferrite, the aim being to produce a 50:50 mix although in commercial alloys the mix may be 60:40. Duplex steel have improved strength over austenitic stainless steels and also improved resistance to localised corrosion particularly pitting, crevice corrosion and stress corrosion cracking. They are characterised by high chromium and lower nickel contents than austenitic stainless steels.

Austenitic stainless steel

Austenitic stainless steel is a specific type of stainless steel alloy. Stainless steels may be classified by their crystalline structure into four main types: austenitic, ferritic, martensitic and duplex. ... Type 316 is the next most common austenitic stainless steel.

Formable tubes for versatile use

Austenitic stainless steel is the most used stainless material in the world. The standard grades for everyday business are covered mainly by 304 and 316L/316Ti types of austenitics. 

Austenitic stainless steel sustains its mechanical values, even at higher temperatures. This sustainability of mechanical values makes it possible to obtain 30-minute fire resistance in stainless steel structures, without any additional fire protection.

Advantages of austenitic stainless steel:

• Excellent formability
• Excellent corrosion resistance
  
• Toughness at low temperatures
  
• Good weldability
  
• Fire resistance
  

Available material grades for austenitic stainless steel rectangular tubes:

• Austenitic metric (1.4301, 1.4307, 1.4404, 1.4571)
  
• Austenitic imperial (304, 304L, 316L, 316 Ti)
  
• Also special project materials by request

Defining Characteristics

Ferritic steels have a body-centered cubic (BCC) grain structure, but the austenitic range of stainless steels are defined by their face-centered cubic (FCC) crystal structure, which has one atom at each corner of the cube and one in the middle of each face. This grain structure forms when a sufficient quantity of nickel is added to the alloy—8 to 10 percent in a standard 18 percent chromium alloy.

In addition to being non-magnetic, austenitic stainless steels are not heat treatable. They can be cold worked to improve hardness, strength, and stress resistance, however. A solution anneals heated to 1045° C followed by quenching or rapid cooling will restore the alloy's original condition, including removing alloy segregation and re-establishing ductility after cold working.

Nickel-based austenitic steels are classified as 300 series. The most common of these is grade 304, which typically contains 18 percent chromium and 8 percent nickel.

Eight percent is the minimum amount of nickel that can be added to a stainless steel containing 18 percent chromium in order to completely convert all the ferrite to austenite. Molybdenum can also be added to a level of about 2 percent for grade 316 to improve corrosion resistance.

Although nickel is the alloying element most commonly used to produce austenitic steels, nitrogen offers another possibility. Stainless steels with a low nickel and high nitrogen content are classified as 200 series. Because it is a gas, however, only limited amounts of nitrogen can be added before deleterious effects arise, including the formation of nitrides and gas porosity that weaken the alloy.

The addition of manganese, also an austenite former, combined with the inclusion of nitrogen allows for greater amounts of the gas to be added. As a result, these two elements, along with copper—which also has austenite-forming properties—are often used to replace nickel in 200 series stainless steels.

The 200 series—also referred to as chromium-manganese (CrMn) stainless steels—were developed in the 1940s and 1950s when nickel was in short supply and prices were high. It is now considered a cost-effective substitute for 300 series stainless steels that can provide an additional benefit of improved yield strength.

Straight grades of austenitic stainless steels have a maximum carbon content of 0.08 percent. Low carbon grades or "L" grades contain a maximum carbon content of 0.03 percent in order to avoid carbide precipitation.

Austenitic steels are non-magnetic in the annealed condition, although they can become slightly magnetic when cold worked. They have good formability and weldability, as well as excellent toughness, particularly at low or cryogenic temperatures. Austenitic grades also have a low yield stress and relatively high tensile strength.

While austenitic steels are more expensive than ferritic stainless steels, they are generally more durable and corrosion resistant.

Applications

Austenitic stainless steels are used in a wide range of applications, including:

• Automotive trim
• Cookware
• Food and beverage equipment
• Industrial equipment

Applications by Steel Grade

304 and 304L (standard grade):

• Tanks
  
• Storage vessels and pipes for corrosive liquids
  
• Mining, chemical, cryogenic, food and beverage, and pharmaceutical equipment
  
• Cutlery
  
• Architecture
  
• Sinks
  

309 and 310 (high chrome and nickel grades):

• Furnace, kiln, and catalytic converter components
  
• 318 and 316L (high moly content grades):
• Chemical storage tanks, pressure vessels, and piping
  

321 and 316Ti ("stabilized" grades):

• Afterburners
  
• Super heaters
  
• Compensators
  
• Expansion bellows
  

200 Series (low nickel grades):

• Dishwashers and washing machines
  
• Cutlery and cookware
  
• In-house water tanks
  
• Indoor and nonstructural architecture
  
• Food and beverage equipment
  
• Automobile parts