abc® Aalco is a registered trademark of Aalco Metals Ltd
© Copyright: Aalco Metals Ltd, The Hersham Centre, Hersham Green, Hersham, Surrey KT12 4HP
All Data is indicative only and must not be seen as a substitute for the full specification from which it is drawn.
In particular, the mechanical property requirements vary widely with product form and product dimensions.
For more complete details please refer to the relevant specification – The BS EN Specifications for Stainless Steel
are listed on a separate Datasheet.
Stainless Steel Grade 303 / 1.4305
Stainless steel type 1.4305 is popularly
known as grade 303 stainless steel.
Grade 303 is the most readily
machineable of all the austenitic
grades of stainless steel.
The machineable nature of grade 303
is due to the presence of Sulphur in the
steel composition. Whilst the Sulphur
improves machining, it also causes a
decrease in the corrosion resistance
and a slight lowering of the toughness.
The corrosion resistance of type 303 is
lower than that for 304. The toughness
is still excellent as with other
austenitic grades.
Property data given in this document is
typical for bar products covered by
ASTM A582. ASTM, EN or other
standards may cover products sold by
Aalco. It is reasonable to expect
specifications in these standards to be
similar but not necessarily identical to
those given in this datasheet.
Applications
Grade 303 is used in applications that
require parts to be heavily machined. These
applications include:
Nuts and bolts
Screws
Gears
Aircraft fittings
Bushings
Shafts
Typical Chemical Composition
% 303
C 0.15max
Mn 2.0
Si 1.0
P 0.20
S 0.15min
Cr 17-19
Ni 8-10
Typical Mechanical Properties
Grade 303
Tensile Strength (MPa) 500
Proof Stress 0.2% (MPa) 190
Elongation A5 (%) 35
Hardness Rockwell (HB) 262max
Typical Physical Properties
Property Value
Density 8.03 g/cm3
Melting Point 1455°C
Modulus of Elasticity 193 GPa
Electrical Resistivity 0.072x10-6 Ω.m
Thermal
Conductivity
16.3 W/m.K at
100°C
Thermal Expansion 17.3x10
-6 /K at
100°C
Alloy Designations
Stainless steel 303 also corresponds to the
following standard designations and
specifications:
Euronorm UNS BS En Grade
1.4305 S30300 303S31 58M 303
Corrosion Resistance
Sulphur additions to the composition act as
initiation sites for pitting corrosion. This
decreases the corrosion resistance of 303
stainless steel to less than that for 304.
However. corrosion resistance remains
good in mild environments.
In chloride containing environments over
60°C, 303 stainless steel is subject to
pitting and crevice corrosion. Grade 303
stainless is not suitable for use in marine
environments.
X
abc® Aalco is a registered trademark of Aalco Metals Ltd
© Copyright: Aalco Metals Ltd, The Hersham Centre, Hersham Green, Hersham, Surrey KT12 4HP
All Data is indicative only and must not be seen as a substitute for the full specification from which it is drawn.
In particular, the mechanical property requirements vary widely with product form and product dimensions.
For more complete details please refer to the relevant specification – The BS EN Specifications for Stainless Steel
are listed on a separate Datasheet.
Heat Resistance
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
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
Type 303 is not readily cold workable.
Some cold working is possible but sharp
bending should not be attempted.
Hot Working
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
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
The sulphur addition present in 303
stainless steel results in poor weldability. If
303 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.
Supplied Forms
Type 303 is typically only supplied by Aalco
as:
Round bar
Hexagonal bar.
This information is based on our present
knowledge and is given in good faith. However,
no liability will be accepted by the Company is
respect of any action taken by any third party in
reliance thereon
As the products detailed may be used for a wide
variety of purposes and as the Company has no
control over their use; the Company specifically
excludes all conditions or warranties expressed
or implied by statute or otherwise as to
dimensions, properties and/or fitness for any
particular purpose. Any advice given by the
Company to any third party is given for that
party’s assistance only and without liability on
the part of the Company.
Any contract between the Company and a
customer will be subject to the Company’s
Conditions of Sale. The extent of the Company’s
liabilities to any customer is clearly set out in
those Conditions; a copy of which is available on
request.