303 Stainless Steel Plate
303 stainless steel is a type of free-machining austenitic stainless steel designed specifically to improve machinability. It is made by adding sulfur (S) or selenium (Se) to 304 stainless steel, sacrificing some corrosion resistance and weldability, making it extremely suitable for high-speed, high-volume machining on automatic lathes.
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Product Introduction

303 Stainless Steel Plate is the most widely specified free-machining austenitic stainless steel. It is a modified variant of the basic "18-8" composition (Type 304), with the deliberate addition of sulfur (and sometimes selenium or phosphorus) to dramatically enhance its machinability.

This alloy is engineered for one primary purpose: to be efficiently machined into high-volume, complex precision parts on automatic screw machines (CNC lathes). The added inclusions act as chip breakers, producing short, broken chips instead of the long, stringy chips characteristic of standard 304. This results in higher machining speeds, longer tool life, superior surface finishes, and lower overall production costs. It retains good corrosion resistance and mechanical properties comparable to 304, making it the ideal choice for parts that must be both easily machined and corrosion-resistant, such as fasteners, fittings, shafts, and valves.

Product parameters


tem / ParameterSpecification for 303 (UNS S30300)Notes / Significance
Key FeatureOptimized for Machinability. The standard grade for high-speed, high-volume production of precision turned parts.The primary and often sole reason for choosing 303 over 304.
Common DesignationsUNS S30300, AISI 303, EN 1.4305, X8CrNiS18-9, JIS SUS303, Y1Cr18Ni9The "S" in European designations denotes sulfur addition.
Chemical Composition (Typical wt.%)C: ≤ 0.15
Cr: 17.0 - 19.0
Ni: 8.0 - 10.0
S: 0.15 - 0.35 (min)P: ≤ 0.20 (may be added)
High sulfur content is critical for free-machining properties. Phosphorus or selenium may also be added.
Mechanical Properties (Annealed Bar/Plate)Tensile Strength (Rm): ≥ 550 MPa
Yield Strength (Rp0.2): ≥ 240 MPa
Elongation (A): ≥ 45%
Hardness (HB): ≤ 262
Mechanical properties are very similar to 304 in the annealed condition.
Physical PropertiesDensity: ~7.88 - 7.93 g/cm³
Modulus of Elasticity: 193 GPa
Melting Range: 1400 - 1420 °C
Physical properties are nearly identical to 304. Non-magnetic when annealed.
Key StandardsASTM A581/A581M (Standard Specification for Free-Machining Stainless Steel Wire and Wire Rods)
ASTM A582/A582M (Standard Specification for Free-Machining Stainless Steel Bars)
ASTM A895 (Standard Specification for Free-Machining Stainless Steel Plate, Sheet, and Strip)
A895 is the direct standard for plate, sheet, and strip products.
Common ApplicationsScrews, nuts, bolts, shafts, gears, valve stems, fittings, bushings, and any component requiring extensive machining on automatic screw machines.The quintessential material for high-volume CNC turned and Swiss-machined components.

Surface selection

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Packaging and transportation

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FACTORY SHOW

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FAQ

Q:What about your price? 
A:Our price is very competitive because we are a factory. Feel free to contact us if you are interested in our products. 

Q:Can I go to your factory to visit?
A:Of course, we welcome customers from all over the world to visit our factory.

Q:What product information do I need to provide?
A:You need to provide the grade, width, thickness, coating and the number of tons you need to purchase. 

Q:Does the product have quality inspection before loading? 
A:Of course, all our products are strictly tested for quality before packaging, and unqualified products will be destroyed.we
accept the third party inspection absolutely. 

Q:How about the delivery time? 
A:Within 3-15 days after we confirm you requirement. 

Q:What is your terms of payment ?
A:T/T, L/C at sight, Cash, Western Union are all accepted if you have other payment,please contact me. 

Q: Do you provide samples? 
A:Yes,we could offer the sample for you to test but please pay freight fee.

Q:How do we trust your company? 
A:We are a specialized company focusing on global steel trading and supply chain services. Our mission is to provide high-quality, multi-specification, and one-stop steel products and solutions to customers worldwide.

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