After 304, this is the most common stainless steel on the market. Again it is an austenitic grade with the addition of 2-3% molybdenum which further improves corrosion resistance. It is often referred to as a marine grade stainless steel because of its effective resistance to chloride corrosion in comparison to other stainless steel grades.
The material has superior welding and forming qualities. Grade 316 will require post-weld annealing to promote maximum corrosion resistance, though this is not necessary if Type 316L is used.
Origins from the Paper Industry
The steel was initially produced for the paper producing industry as it has been shown to be highly resistant to the sulphur compounds used in paper processing.
Typical applications for this material are now widespread due to its superior corrosion resistance properties when compared to Grade 304. Type 316 stainless can be found in heat exchangers, pharmaceutical equipment, dairies and breweries, marine fittings, coastal architectural fascia and fittings and in food preparation areas.
316 & 316L steel plate and pipes have common properties and are often stocked with Dual Certification, where it is determined that both have properties and composition which comply with both steel types.
Type 316H is excluded from this scenario by virtue of the fact that unlike 316 & 316L, 316H is engineered to work in elevated working temperatures.
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Product Range
Specifications: ASTM A269 / ASTM A312
Sizes (Seamless): 1/2" NB - 24" NB
Sizes (ERW): 1/2" NB - 24" NB
Sizes (EFW): 6" NB - 100" NB
Wall Thickness available:Schedule 5S - Schedule XXS (heavier on request)
Other Materials Testing:
NACE MR0175, H2 SERVICE, OXYGEN SERVICE, CRYO SERVICE, etc.
Dimensions:
All Pipes is manufactured and inspected/tested to the relevant standards including ASTM A269 / ASTM A312
Background of 316
Grade 316 is the standard molybdenum-bearing grade, second in importance to 304 amongst the austenitic stainless steels. The molybdenum gives 316 better overall corrosion resistant properties than Grade 304, particularly higher resistance to pitting and crevice corrosion in chloride environments. It has excellent forming and welding characteristics. It is readily brake or roll formed into a variety of parts for applications in the industrial, architectural, and transportation fields. Grade 316 also has outstanding welding characteristics. Post-weld annealing is not required when welding thin sections.
Grade 316L, the low carbon version of 316 and is immune from sensitisation (grain boundary carbide precipitation). Thus it is extensively used in heavy gauge welded components (over about 6mm). Grade 316H, with its higher carbon content has application at elevated temperatures, as does stabilized grade 316Ti.
The austenitic structure also gives these grades excellent toughness, even down to cryogenic temperatures.
Composition of 316
Table 1. Composition ranges for 316 grade of stainless steels.
Grade |
|
C |
Mn |
Si |
P |
S |
Cr |
Mo |
Ni |
N |
316 |
Min |
- |
- |
- |
0 |
- |
16.0 |
2.00 |
10.0 |
- |
Max |
0.08 |
2.0 |
0.75 |
0.045 |
0.03 |
18.0 |
3.00 |
14.0 |
0.10 |
316L |
Min |
- |
- |
- |
- |
- |
16.0 |
2.00 |
10.0 |
- |
Max |
0.03 |
2.0 |
0.75 |
0.045 |
0.03 |
18.0 |
3.00 |
14.0 |
0.10 |
316H |
Min |
0.04 |
0.04 |
0 |
- |
- |
16.0 |
2.00 |
10.0 |
- |
max |
0.10 |
0.10 |
0.75 |
0.045 |
0.03 |
18.0 |
3.00 |
14.0 |
- |
Mechanical Properties
Table 2. Mechanical properties of 316 grade stainless steels.
Grade |
Tensile Str
(MPa) min |
Yield Str
0.2% Proof
(MPa) min |
Elong
(% in 50mm) min |
Hardness |
Rockwell B (HR B) max |
Brinell (HB) max |
316 |
515 |
205 |
40 |
95 |
217 |
316L |
485 |
170 |
40 |
95 |
217 |
316H |
515 |
205 |
40 |
95 |
217 |
Note: 316H also has a requirement for a grain size of ASTM no. 7 or coarser.
Physical Properties
Table 3. Typical physical properties for 316 grade stainless steels.
Grade |
Density
(kg/m3) |
Elastic Modulus
(GPa) |
Mean Co-eff of Thermal Expansion (µm/m/0C) |
Thermal Conductivity
(W/m.K) |
Specific Heat 0-1000C
(J/kg.K) |
Elec Resistivity
(nΩ.m) |
0-1000C |
0-3150C |
0-5380C |
At 1000C |
At 5000C |
316/L/H |
8000 |
193 |
15.9 |
16.2 |
17.5 |
16.3 |
21.5 |
500 |
740 |
Grade Specification Comparison of 316
Table 4. Grade specifications for 316 grade stainless steels.
Grade |
UNS
No |
Old British |
Euronorm |
Swedish
SS |
Japanese
JIS |
BS |
En |
No |
Name |
316 |
S31600 |
316S31 |
58H, 58J |
1.4401 |
X5CrNiMo17-12-2 |
2347 |
SUS 316 |
316L |
S31603 |
316S11 |
- |
1.4404 |
X2CrNiMo17-12-2 |
2348 |
SUS 316L |
316H |
S31609 |
316S51 |
- |
- |
- |
- |
- |
Note: These comparisons are approximate only. The list is intended as a comparison of functionally similar materials not as a schedule of contractual equivalents. If exact equivalents are needed original specifications must be consulted.
Corrosion Resistance of 316
Excellent in a range of atmospheric environments and many corrosive media - generally more resistant than 304. Subject to pitting and crevice corrosion in warm chloride environments, and to stress corrosion cracking above about 600C. Considered resistant to potable water with up to about 1000mg/L chlorides at ambient temperatures, reducing to about 500mg/L at 600C.
316 is usually regarded as the standard “marine grade stainless steel", but it is not resistant to warm sea water. In many marine environments 316 does exhibit surface corrosion, usually visible as brown staining. This is particularly associated with crevices and rough surface finish.
Heat Treatment of 316
Solution Treatment (Annealing) - Heat to 1010-11200C and cool rapidly. These grades cannot be hardened by thermal treatment.
