instrument and implant grade metal alloys

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Stainless Steel 303 (1.4305) Medical Alloy

Stainless Steel 303 is the classic free-machining austenitic stainless steel grade. Our material is certified to ASTM F899 (Standard Specification for Wrought Stainless Steel For Surgical Instruments) and ISO 7151 (Surgical Instruments) making it ideal for a range of applications from sanitary wares to micro-mechanical engineering components.

Stainless steel grade 303 can only be strengthened by cold working, not heat treatment, which can lead to the formation of alpha ferrite martensite, considerably increasing its ferromagnetism up to a relative magnetic permeability > 1. The presence of MnS inclusions and of delta ferrite may increasing the difficulty in polishing this grade.

Non-medical versions of 303 stainless steel are available to AMS 5640 in two different types depending on the addition of Sulphur (AMS 5640 Type 1) or Selenium (AMS 5640 Type 2).

Typical Chemical Composition

C Si Mn P S Cr Mo Ni V Nb N Cu Fe
Min 0.15 17.00 8.00 Balance
Max 0.1 1.00 2.00 0.045 0.35 19.00 11.00 0.11 1.00

Typical Mechanical Properties

(Diameter mm)
Tensile (Rm)
Yield (R0.2%)
A4d (%)
Less than 12.7mm 125ksi (max) 26 HRC
12.7mm to 50.8mm 140-255 (HB)
Over 50.8mm 255 max (HB)


ISO 7151-1 (N)
EN / DIN X8CrNiS 18-9
JIS 303
UNS S30300
AMS 5640


303 1.4305 stainless steel alloy is readily available in precision ground bar from 3.0mm diameter to 20.0mm diameter. Contact sales for more information.

Disclaimer : Every effort is made to ensure that technical specifications are accurate. However, technical specifications included herein should be used as a guideline only. All specifications are subject to change without notice.

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NOTE: Weights calculated are theoretical. Manufacturing tolerances should be allowed for and results adjusted accordingly.