Aircraft Steel BS S99/ 5S99D / 5S99G (826M40)


Technical Data Sheet

 

Chemical Composition Limits
Weight% C Si Mn P+S max Cr Mo Ni Other Al
S99 0.36-0.44 0.10-0.35 0.45-0.70 P 0.025
S 0.020
0.50-0.80 0.45-0.65 2.30-2.80 - 0.015-0.050
Chemically similar British Specifications BS.970 Pt2
Weight% C Si Mn P+S max Cr Mo Ni Other
826M40 0.36-0.44 0.10-0.35 0.45-0.70 P 0.040
S 0.050
0.50-0.80 0.45-0.65 2.30-2.80 -
EN26 0.34-0.44 0.10-0.35 0.50-0.70 - 0.50-0.80 0.40-0.70 2.30-2.80 -
Other Chemically similar Specifications
Weight% C Si Mn P+S max Cr Mo Ni Other
WS 1.6745
40NiMoCr105
0.37-0.43 0.15-0.35 0.50-0.70 0.035 max 0.60-0.80 0.40-0.60 2.4-2.7 -

BS S99, along with S98 is the British aerospace equivalent of 826M40. A 2 1/2% Nickel-Chrome-Moly high carbon steel, it is available in bars and forgings. S98 is generally supplied as bright bar in either the softened condition (5S99D) or hardened and tempered (5S99G).

Typical Mechanical Properties

 

Grade Treatment Tensile Strength Rm N/mm² Proof Stress Rp 0.2, N/mm² Elongation in 5.65 √Cross Sectional Area% Hardness HB Ruling Section
3S99D Solution Annealed - - - 277 max -
3S99G Hardened and Tempered 1230-1420 1080 10 363-415 6"

Availability
Alloy S99 is available in Bar . For all stock availability contact Sales.

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.