Aircraft Stainless Steel BS S143 / 2S143 (FV 520)

Technical Data Sheet

S143 is a British aerospace grade, precipitation hardenable stainless steel which combines high mechanical strength with moderate corrosion resistance. It is widely used for mechanical components in aerospace and defense applications as well as other high-tech mechanical applications. It is chemically identical to BS S144 and BS S145 and is supplied as bright bar in the finally heat treated condition, designated BS S143D. The heat treatment is as follows:

Solution Treatment : 1050°C plus air cool
Precipitation Treatment (1st Stage): 750 °C / 2hrs plus air cool
Precipitation Treatment (Final Stage): 550 °C / 2hrs plus air cool


Chemical Composition Limits
Weight% C Si Mn P + S max Cr Cu Mo Nb Ni
S143 0.07 0.6 1.0 P 0.035
S 0.025
13.2-14.7 1.20-2.0 1.20-2.0 0.10-0.40 5.0-5.80

Typical Mechanical Properties

Grade Condition Tensile Strength N/mm² Yield Strength N/mm² Elongation (%) Hardness Ruling Section
S143 Finally Heat Treated 930-1080 780 15 277-341 -
S143 Finally Heat Treated Softened 930-1080 780 12
transverse test piece
331 max
S143 Softened       331 max -

Alloy S143 is available in Bars and Forgings. For all stock availability contact Sales.


BS S144
BS S145
Def Stan 95-14

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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.