BS S99

The alloy is typically provided in the annealed or bright annealed condition and benefits from high tensile strength combined with good notch toughness. BS S99 is high-carbon steel with nickel, chromium and molybdenum. The molybdenum prevents the material from being responsive to temper brittleness. Other benefits include good creep resistance and mechanical property retention at low and elevated temperatures.

Aerospace Grade

BS S99 is classed as an aircraft alloy but finds widespread use in engineering applications, particularly in large cross-sections if the alloy is quenched and tempered. Examples include aircraft parts, heavy-duty gears, high-strength bolts, and fasteners.

Stock Availability

Smiths Advanced Metals stocks BS S99 steel bars in the hardened and tempered condition.