Fuel Cell Plates

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).

The austenitic structure also gives these grades excellent toughness, even down to cryogenic temperatures.

Types 316, 316L are molybdenum-bearing austenitic stainless steels which are more resistant to general corrosion and pitting/crevice corrosion than the conventional chromium-nickel austenitic stainless steels such as Type 304. These alloys also offer higher creep, stress-to-rupture and tensile strength at elevated temperature. In addition to excellent corrosion resistance and strength properties, the Types 316, 316L Cr-Ni-Mo alloys also provide the excellent fabricability and formability which are typical of the austenitic stainless steels. Applications for Types 316 and 316L alloys include acetic acid compounds, brandy vats, corn products refining equipment, fasteners, kettles for cooking ketchup, pharmaceutical processing equipment, phosphate industry parts, photographic film processing equipment, pitting-corrosion resistance, pulp and paper processing equipment, smokestacks, textile finishing equipment, textile mill kiers, water softener tanks, wire cloth and screens (industrial) and yeast tubes. Types 316, 316L.

RESISTANCE TO CORROSION
Types 316, 316L are more resistant to
atmospheric and other mild types of corrosion than Types 304 and 304L.

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.

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.

Source: Atlas Steels Australia

C - Carbon
Mn - Manganese
P - Phosphorus
S - Sulfer

Si - Silicon

Cr - Chromium

Ni - Nickel
Mo - Molybdenum

Cu - Copper

N - Nitrogen
Ti - Titanium

Grade	C	Mn	P	S	Si	Cr	Ni	Mo	Cu	N	Ti
304	.08	2	.045	.030	1.00	18-20	8-10	.75	.75	.10	-
304L	.03	2	.045	.030	1.00	18-20	8-12	.75	.75	.10	-
316	.08	2	.040	.030	1.00	16-18	10-14	2-3	.75	-	-
316L	.03	2	.040	.030	1.00	16-18	10-14	2-3	.75	-	-

General Description By Grade

Grade 304/ Grade 304L	Type is the basic (18-8) type stainless. It work hardens faster than Type 301, but offers better corrosion resistance. Some welding applications may benefit from Type 304L, a lower carbon version of 304. Type 304 is used in many applications including laser welded tubing, bellows, laser and chemical etching, medical and food applications.
Grade 316/ Grade 316L	Type 316/316L has a higher Nickel content (10% min) than 304 (8% min) and offers superior corrosion resistance. The 316L version of the alloy has less Carbon to promote resistance to intergranular attack after welding has taken place. Type 316/316L is often used in marine environments, aerospace and chemical applications.

Test your stainless steel to see if you got the right stuff or ripped off?

(Molybdenum Spot Test (Mo))

Stainless steels which contain significant Molybdenum from those which do not.

The most common use is to sort 304 from 316

1. Clean the steel surface; use abrasive paper, and if necessary degrease and dry.
2. Use "Decapoli 304/316" solution – shake well, then place one drop on the steel.
3. Place similar drops on standard 304 and 316 samples.
4. Darkening of the yellow drop in 2 to 4 minutes indicates significant Mo. Compare with indications on standard samples.
5. Wash or wipe samples clean.

Avoid contact of test solution on skin, and particularly eyes. Wash off immediately if contacted. Reliable results only obtained if samples all the same temperature and freshly cleaned. Avoid very low sample temperatures. Some Heats of "Mo-free" stainless steels, such as 304, contain enough Mo to give a slight reaction. Standard comparison samples must be used.