303 Stainless Steel
wilsonpipeline Stainless inventory includes 303 grade stainless steel (UNS S30300) in Flanges, Pipe Fittings, Pipe.
General Properties
Alloy 303 is a non-magnetic, austenitic stainless steel that is not hardenable by heat treatment. It is the free machining modification of the basic 18% chromium / 8% nickel stainless steel. Alloy 303 was specially designed to exhibit improved machinability while maintaining good mechanical and corrosion resistant properties Due to the presence of sulfur in the steel composition, Alloy 303 is the most readily machineable austenitic stainless steel; however, the sulfur addition does lower Alloy 303’s corrosion resistance to below that of Alloy 304. Like other austenitic grades, Alloy 303 demonstrates excellent toughness, although the sulfur does reduce this a little as well.
Applications
Alloy 303 is frequently used in applications that require parts to be heavily machined. Some examples include:
Nuts and bolts
Aircraft fittings
Gears
Screws
Shafts
Electrical switchgear components
Bushings
Standards – Alloy 303
ASTM/ASME ……………. UNS S30300
EURONORM ……………. FeMi35Cr20Cu4Mo2
DIN ………………………… 2.4660
Corrosion Resistance
Good resistance to mildly corrosive atmospheres, but significantly less than Alloy 304
When additional sulfur is added to improve machinability, it can often slightly reduce corrosion resistance
In most dry and mild corrosive environments, Alloy 303 is comparable to other unmodified alloys
Should not be exposed to moist, marine environments as it is subject to rapid-pitting corrosion and a rust film will tend to form
Like other common austenitic stainless steels, it is subject to corrosion cracking in chloride environments above 60oC
Heat Resistance
Good oxidation resistance at temperatures up to 1700oF (927 oC)
Continuous use at temperatures above 1400oF (760oC) is not usually recommended due to carbide precipitation which can lead to irregular scaling
Does not have a low carbon content so it is also vulnerable to sensitisation
Welding Characteristics
Not generally recommended, but may be welded with some difficulty
May be welded with Alloy 310 electrodes
Should be annealed after welding to re-dissolve precipitated carbides
Machinability
High machining rates can be obtained in the annealed condition with hardness in the range of 200 to 240 Brinell
Will work harden, therefore, it should be machined at reduced surface feet per minute and heavier feeds to prevent glazing at the tool interface.
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