Aircraft Steel BS S99/ 5S99D / 5S99G (826M40)
Technical Data Sheet
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).
| 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 | - | |
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.
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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.
