Corrosion Resistance
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 60°C. Considered
resistant to potable water with up to about 1000mg/L
chlorides at ambient temperatures, reducing to about
500mg/L at 60°C.
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 Resistance
Good oxidation
resistance in intermittent service to 870°C and in
continuous service to 925°C. Continuous use of 316 in the
425-860°C range is not recommended if subsequent aqueous
corrosion resistance is important. Grade 316L is more
resistant to carbide precipitation and can be used in the
above temperature range. Grade 316H has higher strength at
elevated temperatures and is sometimes used for structural
and pressure-containing applications at temperatures above
about 500°C.
Heat Treatment
Solution Treatment
(Annealing) - Heat to 1010-1120°C and cool rapidly. These
grades cannot be hardened by thermal treatment.
Welding
Excellent
weldability by all standard fusion methods, both with and
without filler metals. AS 1554.6 pre-qualifies welding of
316 with Grade 316 and 316L with Grade 316L rods or
electrodes (or their high silicon equivalents). Heavy
welded sections in Grade 316 require post-weld annealing
for maximum corrosion resistance. This is not required for
316L. Grade 316Ti may also be used as an alternative to
316 for heavy section welding.
Machining
A “Ugima” improved
machinability version of grade 316 is available in round
and hollow bar products. This machines significantly
better than standard 316 or 316L, giving higher machining
rates and lower tool wear in many operations.
Dual Certification
It is common for
316 and 316L to be stocked in "Dual Certified" form -
mainly in plate and pipe. These items have chemical and
mechanical properties complying with both 316 and 316L
specifications. Such dual certified product does not meet
316H specification and may be unacceptable for high
temperature applications.
