Type 304: Stainless Steel
The most
common grade; the classic 18/8 stainless steel. Its the most versatile
and most widely used stainless steel, available in a wider range of
products, forms and finishes than any other, its balanced austenitic
structure enables it to be severely deep drawn without intermediate annealing.Grade 304 has good oxidation resistance in intermittent
service to 870°C and in continuous service to 925°C. Continuous use of
304 in the 425-860°C range is not recommended if subsequent aqueous
corrosion resistance is important.Grade 304 is excellent in a wide range
of atmospheric environments and many corrosive media, although subject
to pitting and crevice corrosion in warm chloride environments, and to
stress corrosion cracking above about 60°C.
Grade 304 has excellent forming and welding characteristics by all
standard fusion methods, both with and without filler metals, although
heavy welded sections in Grade 304 may require post-weld annealing for
maximum corrosion resistance, post-weld annealing is not required when
welding thin sections.
Grade 304's excellent overall toughness and low temperature properties
respond well to hardening by cold working. It also benefits from ease of
fabrication, ease of cleaning and the beauty of its appearance.
Type 316: Stainless Steel
The second most common grade (after 304) amongst the austenitic
stainless steels, its austenitic structure also gives the Grade 316
excellent toughness, even down to cryogenic temperatures. Grade 316 is
the standard molybdenum-bearing grade, alloy addition of molybdenum
gives Grade 316 excellent overall corrosion resistant properties in a
range of
atmospheric environments and many corrosive media and a
particularly higher resistance to pitting and crevice corrosion than
that of Grade 304.
Grade 316 however is subject to pitting and crevice corrosion in warm
chloride environments, and to stress corrosion cracking above about
60°C.
Grade 316 has excellent forming and welding characteristics by all
standard fusion methods, both with and without filler metals. Heavy
welded sections in Grade 316 will require post-weld annealing for
maximum corrosion resistance however post-weld annealing is not required
when welding thin sections.
Grade 316 also has 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 316 steel is used in the handling of certain food and
pharmaceutical products where it is often required in order to minimize
metallic contamination.
Grade 316 is also known as Marine Grade
