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Monday 26 October 2020
  • 316 Stainless Steel Data sheet
  • 316 Stainless Steel Data sheet
  • 316 Stainless Steel Data sheet
  • 316 Stainless Steel Data sheet
  • 316 Stainless Steel Data sheet
  • 316 Stainless Steel Data sheet
  • 316 Stainless Steel Data sheet
  • 316 Stainless Steel Data sheet

316

Alloy

UNS Number

SAE Number

  316L

  S31600 

  30316 

 
GENERAL PROPERTIES

 

Types 316 and 316L are molybdenum-bearing austenitic stainless steel which are more resistant to general corrosion and pitting/crevice corrosion than the conventional chromium nickel austenitic stainless steel such as Type 304. These alloys also offer higher creep, stress-to-rupture and tensile strength at elevated temperature. Types 316 and 316L generally contain 2 to 3% molybdenum for improved corrosion resistance. 

In addition to excellent corrosion resistance and strength properties, Types 316 and 316L alloys also provide the excellent fabricability and formability which are typical of the austenitic stainless steels. 

 
RESISTANCE TO CORROSION

 

General Corrosion 
Types 316 and 316L are more resistant to atmospheric and other mild types of corrosion than the 18-8 stainless steels. In general, media that do not corrode 18-8 stainless steels will not attack these molybdenum-containing grades. One known exception is highly oxidizing acids such as nitric acid to which the molybdenum-bearing stainless steels are less resistant. 

Type 316 is considerably more resistant than any of the other chromium-nickel types to solutions of sulfuric acid. At temperature as high as 120° F (49° C), Type 316 is resistant to concentrations of this acid up to 5 percent. At temperatures under 100° F (38° C), this type has excellent resistance to higher concentrations. Service tests are usually desirable as operating conditions and acid contaminants may significantly affect corrosion rate. Where condensation of sulfur-bearing gases occurs, these alloys are much more resistant than other types of stainless steels. In such applications, however, the acid concentration has marked influence on the rate of attack and should be carefully determined. 

The molybdenum-bearing Type 316 stainless steel also provides resistance to a wide variety of other environments. This alloy offers excellent resistance to boiling 20% phosphoric acid. It is widely used in handling hot organic and fatty acids. This is a factor in the manufacture and handling of certain food and pharmaceutical products where the molybdenum-containing stainless steels are often required in order to minimize metallic contamination. 

Generally, the Type 316 grade can be considered to perform equally well for a given environment. A notable exception is in environments sufficiently corrosive to cause intergranular corrosion of welds and heat-affected zones on susceptible alloys. In such media, Type 316L is preferred over Type 316 for the welded condition since low carbon levels enhance resistance to intergranular corrosion. 

Pitting/Crevice Corrosion 
Resistance of austenitic stainless steels to pitting and/or crevice corrosion in the presence of chloride or halide ions is enhanced by higher chromium (Cr), molybdenum (Mo), and nitrogen (N) content. A relative measure of pitting resistance is given by the PREN (Pitting Resistance Equivalent, including Nitrogen) calculation, where PREN = Cr+3.3Mo+16N. The PREN of Type 316 and 316L (24.2) is better than that of Type 304 (PREN=19.0), reflecting the better pitting resistance which Type 316 (or 316L) offers due to its Mo content. 

Type 304 stainless steel is considered to resist pitting and crevice corrosion in waters containing up to about 100 ppm chloride. The Mo-bearing Type 316 alloy on the other hand, will handle waters with up to about 2000 ppm chloride. Although this alloy has been used with mixed success in seawater (19,000 ppm chloride) it is not recommended for such use. The Type 316 alloy is considered to be adequate for some marine environment applications such as boat rails and hardware, and facades of buildings near the ocean which are exposed to salt spray. Type 316 stainless steel performs without evidence of corrosion in the 100-hou, 5% salt spray (ASTM-B-117) test. 

Intergranular Corrosion 
Type 316 is susceptible to precipitation of chromium carbides in grain boundaries when exposed to temperatures in the 800° F to 1500° F (427° C to 816° C) range. This “sensitized” steel is subject to intergranular corrosion when exposed to aggressive environments. 

For applications where heavy cross sections cannon be annealed after welding or where low temperature stress relieving treatments are desired, the low carbon Type 316L is available to avoid the hazard of intergranular corrosion. This provides resistance to intergranular attack with any thickness in the as-welded condition or with short periods of exposure in the 800-1500° F (427-826° C) temperature range. Where vessels require stress relieving treatment, short treatments falling within these limits can be employed without affecting the normal excellent corrosion resistance of the metal. Accelerated cooling from higher temperatures for the “L” grade is not needed when very heavy or bulky section have been annealed. 

Type 316L posses the same desirable corrosion resistance and mechanical properties as the corresponding higher carbon Type 316, and offers an additional advantage in highly corrosive applications where intergranular corrosion is a hazard. Although the short duration heating encountered during welding or stress relieving does not produce susceptibility to intergranular corrosion, it should be noted that continuous or prolonged exposure at 800-1500° F (427-816° C) can be harmful from this standpoint with Type 316L. Also, stress relieving between 100-1500° F (593-816° C) may cause some slight Embrittlement of this type. 

Stress Corrosion Cracking 
Austenitic stainless steels are susceptible to stress corrosion cracking (SCC) in halide environments. Although the Type 316 alloy is somewhat more resistant to SCC than the 18 Cr-8 Ni alloys because of the molybdenum content, they still are quite susceptible. Conditions which produce SCC are: (1) presence of halide ion (generally chloride), (2) residual tensile stresses, and (3) temperatures in excess of about 120° F (49° C)

Stresses result from cold deformation or thermal cycles during welding. Annealing or stress relieving heat treatments may be effective in reducing stresses, thereby reducing sensitivity to halide SCC. Although the low carbon “L” grade offers no advantage as regards to SCC resistance, it is a better choice for service in the stress relieved condition in environments which might cause intergranular corrosion. 

 
PHYSICAL PROPERTIES

 

Melting Point 

Density

Specific Gravity

Modulus of Elasticity 
in Tension

  2540-2630° F 
1390-1440° C 

  .29 lb/in³ 
8.027 g/cm³ 

  8.03 

  29 X 106 psi 
200 Gpa 

 
 

MECHANICAL PROPERTIES 

 

Alloy

Temper

Tensile Strength 
Minimum  
(psi)

Yield Strength 
Minimum 0.2% offset  
(psi)

% Elongation 
in 2" Minimum

Notes

316

Annealed

75,000

30,000

40 %

-

All values specified are approximate minimums unless otherwise specified. Values are derived from the applicable AMS and ASTM specifications.

 
 

CHEMICAL PROPERTIES 

 

Alloy

C

Mn

P

S

Si

Cr

Ni

Mo

Cu

N

Other

316

.08

2.00

.040

.030

1.00

16.00-18.00

10.00-14.00

2.00-3.00

.75

-

-

All values are maximum values unless otherwise specified. Values are derived from applicable AMS and ASTM specifications. 

 
 

WELDING 

 

The austenitic stainless steels are considered to be the most weldable of the stainless steels. They are routinely joined by all fusion and resistance welding processes. Tow important considerations for weld joints in these alloys are: (1) avoidance of solidification cracking, and (2) preservation of corrosion resistance of the weld and heat-affected zones. 

Fully austenitic weld deposits are more susceptible to cracking during welding. For this reason Types 316 and 316L "matching” filler metals are formulated to solidify with a small amount of ferrite in the microstructure to minimize cracking susceptibility. 

For weldments to be used in the as-welded condition in corrosive environments, it is advisable to utilize the low carbon Type 316 base metal and filler metals. The higher the carbon level of the material being welded, the greater the likelihood the welding thermal cycles will allow chromium carbide precipitation (sensitization), which could result in intergranular corrosion. The low carbon “L” grade is designed to minimize or avoid sensitization. 

 
 

HEAT TREATMENT 

 

These austenitic stainless steels are provided in the mill annealed condition ready for use. Heat treatment may be necessary during or after fabrication to remove the effects of cold forming or to dissolve precipitated chromium carbides resulting from thermal exposures. For the Type 316 alloy the solution anneal is accomplished by heating in the 1900 to 2150° F (1040 to 1175° C) temperature range followed by air cooling or a water quench, depending on section thickness. Cooling should be sufficiently rapid through the 1500-800° F (816-427° C) range to avoid reprecipitation of chromium carbides and provide optimum corrosion resistance. In every case, the metal should be cooled from the annealing temperature to black heat in less than three minutes.

Contact Us

 

contact phoneT: + 44 (0)1902 409316
Fusion House
The Crescent
Willenhall
West Midlands
WV13 2QR

F: + 44 (0)1902 409304
E: sales@quest4alloys.com