Hardenable Steel BS S155
Technical Data Sheet
BS S155 is the British aerospace equivalent of U.S. steel grade 300M (4340M / AMS 6257). It is a vacuum melted grade supplied in the normalised and tempered/softened condition to allow for final heat treatment. It has a combination of ultra high strength, good fatigue resistance and excellent transverse properties and as such finds many applications in the aerospace industry such as undercarriage components, gears and shafts.
| Chemical Composition Limits | |||||||
| Weight% | C | Si | Mn | P + S max | Cr | Mo | Ni |
| S155 | 0.39-0.44 | 1.50-1.80 | 0.60-0.90 | P 0.015 S 0.01 |
1.60-2.00 | 0.40-0.60 | 3.50-4.50 |
Typical Mechanical Properties
| Grade | Condition | Tensile Strength N/mm² | Yield Strength N/mm² | Elongation (%) | Hardness (HB) | Ruling Section |
| S155 | Norm & Softened | - | - | - | 302 | - |
| S155 | Hardened & Tempered | 1900-2100 | 1550 | 8 | 534-601 | 3" |
| S155 | Hardened & Tempered | 1900-2100 | 1550 | 5 (Transverse test) |
534-601 | 3" |
Availability
Alloy S155 for all stock availability contact Sales.
Specifications
AMS 6257
AMS 6417
AMS 6419
SAE 4340M / 300M
BMS 7.26
DMS 1935
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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.
















