Mechanical Properties of Stainless Steel Alloy
303
Table 2. Typical mechanical properties
for stainless steels
alloy 303
|
Grade |
303 |
|
Tensile Strength
(MPa) |
500-700 |
|
Proof
Stress (MPa) |
190
Min |
|
Elongation A5
(%) |
35 |
Physical Properties of Stainless Steel Alloy
303
Table 3. Typical physical properties
for stainless steels alloy 303
|
Property |
Value |
|
Density |
8.03
kg/m3 |
|
Melting
Point |
1455°C |
|
Modulus of
Elasticity |
193
GPa |
|
Electrical
Resistivity |
0.072x10-6
Ω.m |
|
Thermal
Conductivity |
16.3
W/m.K |
|
Thermal
Expansion |
17.3x10-6
/K |
Alloy Designations
Stainless
steel grade
303 also corresponds to the following standard designations and
specifications:
|
Euronorm |
UNS |
BS |
En |
Grade |
|
1.4305 |
S30300 |
303S31 |
58M |
303 |
Corrosion Resistance of Stainless Steel Alloy
303
Sulphur additions to the composition act as initiation sites
for pitting corrosion. This decreases the corrosion resistance of grade
303 stainless steel to less than that for 304. However corrosion resistance
remains good in mild environments.
In chloride containing environments over 60°C, grade
303 stainless steel is subject to pitting and crevice corrosion. Grade 303
stainless is not suitable for use in marine environments.
Heat Resistance
of Stainless Steel Alloy
303
Grade 303 stainless steel has good resistance to oxidation
when intermittently exposed to temperature up to 760°C temperatures. It also has
good oxidation resistance in continuous service to 870°C. This, however, is not
recommended as 303 is sensitive to carbide precipitation with continuous use at
425-860°C.
Fabrication
of Stainless Steel Alloy
303
Fabrication of all stainless
steels should be done only with tools dedicated to stainless
steel materials. Tooling and work surfaces must be thoroughly cleaned before
use. These precautions are necessary to avoid cross contamination of stainless
steel by easily corroded metals that may discolour the surface of the
fabricated product.
Cold Working of
Stainless Steel Alloy
303
Type 303 is not readily cold workable. Some cold working is
possible but sharp bending should not be attempted.
Hot Working of
Stainless Steel Alloy
303
Fabrication methods, like forging, that involve hot working
like should occur after uniform heating to 1149-1260°C. The fabricated
components should then be rapidly cooled to ensure maximum corrosion
resistance.
Heat Treatment of
Stainless Steel Alloy
303
Grade 303 stainless steel cannot be hardened by heat
treatment.
Solution treatment or annealing can be done by rapid cooling
after heating to 1010-1120°C.
Machinability
Grade 303 stainless steel has excellent machinability. Machining
can be enhanced by adhering to the following rules:
·
Cutting edges must be kept sharp. Dull edges cause excess work
hardening.
·
Cuts should be light but deep enough to prevent work hardening by
riding on the surface of the material.
·
Chip breakers should be employed to assist in ensuring swarf
remains clear of the work
·
Low thermal conductivity of austenitic alloys results in heat
concentrating at the cutting edges. This means coolants and lubricants are
necessary and must be used in large quantities.
Welding of Stainless
Steel Alloy
303
The sulphur addition present in Grade 303
stainless steel results in
poor weldability. If Grade 303 stainless steel must be welded the recommended
filler rods or electrodes are grades 308L and 309 stainless
steels. For maximum corrosion
resistance, the welds must be annealed.
Applications of Stainless Steel Alloy
303
Grade 303 stainless steel is used in applications that require
parts to be heavily machined. These applications include:
·
Nuts and bolts
·
Screws
·
Gears
·
Aircraft fittings
·
Bushings
·
Shafts
Supplied Forms
Grade 303 stainless steel is typically supplied by Aalco in the
following forms:
·
Round bar
·
Hexagonal bar |