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Stainless Steel 303 is a free-machining austenitic grade, made by adding sulphur to the classic 18/8 chromium-nickel recipe. That small change helps chips break cleanly, so 303 cuts faster and with less tool wear than most other stainless steels, which suits busy CNC lathes.
The trade-off is corrosion resistance. 303 holds up well indoors and in mild atmospheres, but it is less resistant than 304 and is not recommended for marine or warm chloride conditions. Welding is also poor, so designs are best joined with threads, press fits or fasteners instead.
We CNC turn and mill 303 from round and hexagon bar, making it a cost-effective choice for nuts, screws, shafts, bushings and fittings in batches large or small. Parts are supplied with a clean as-machined finish. Request an instant quote for 303 stainless steel parts, with delivery anywhere in the UK.
Material
Stainless Steel 303
Description
Strengths
Lead time 10 business days. Free-machining austenitic stainless with excellent chip breaking; ideal for high-volume turned parts such as screws, nuts and shafts.
Weaknesses
Lower corrosion resistance than 304; poor weldability; not for marine use
Silver
Ultimate tensile strength
621 MPa
Yield strength
276 MPa
Modulus of elasticity
193 GPa
Elongation at break
35% min
Density
8.03 g/cm³
Hardness
230 HB max
Corrosion resistance
Good in mild conditions (below 304)
Melting point
1455°C
UK equivalent
1.4305 / 303S31 (EN58M)
Maximum service temperature
Not specified
Thermal expansion coefficient
17.3 × 10⁻⁶ /K
Thermal conductivity
16.3 W/(m·K)
Electrical resistivity
72 μΩ·cm
Machinability
Excellent
Weldability
Poor (sulphur addition)
Nuts, bolts & screws
Shafts & bushings
Gears
Aircraft fittings
Values shown are typical supplier figures for Stainless Steel 303 and may vary with stock condition. Please confirm critical properties before production.
Yes. 303 (1.4305, EN58M) is the free-machining austenitic stainless steel. Its sulphur addition gives excellent chip breaking, making it ideal for turned parts in larger quantities.
303 is well suited to small, precise turned parts such as screws, shafts and bushings. Achievable tolerances depend on part size, geometry and features, so mark any critical tolerances on a 2D drawing with your upload and they will be reviewed and confirmed in your quote.
303 is usually supplied as machined, and passivation can be specified to improve corrosion resistance. It has poor weldability because of its sulphur content.
Typical uses include nuts, bolts and screws, shafts and bushings, gears and aircraft fittings.
Choose 303 when machining efficiency is the priority. Choose 304 for better corrosion resistance and weldability, or 316 for marine and chemical environments. 303 is not recommended for marine use.
The typical lead time shown for 303 stainless steel is 10 business days from an approved order. Quantity, finishing and any heat treatment can affect this, and your quote confirms the date before you order.
Parts in as fast as 10 business days
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