S99 5S99D 5S99G 826M40 Bolts
MDN 99
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
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 | - | |
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" |