This specification covers a premium aircraft-quality, low-alloy Ni-Cr-Mo steel in the form of bars, forgings and forging stock requiring high tensile and toughness values, particular in large cross sections in the hardened and tempered condition. The molybdenum addition prevents the steel from being susceptible to temper brittleness.
These products have been used typically for parts requiring a through-hardening capability up to 6 inches (152,4 mm) in nominal thickness at time of heat treatment but usage is not limited to such applications.
Cr-Ni-Mo- steel for applications requiring high tensile and toughness values, in particular in large cross sections in the quenched and tempered condition. The molybdenum addition prevents the steel from being susceptible to temper brittleness.
| SEL | Market grade |
|---|---|
| 1.6745 | S98 |
| BS | BS |
|---|---|
| S98 | S99 |
| C | Si | Mn | P | S | Cr | Mo | Al | |
|---|---|---|---|---|---|---|---|---|
| 0.36 to 0.44 | 0.10 to 0.35 | 0.45 to 0.7 | max. 0.025 | max. 0.015 | 0.5 to 0.8 | 0.45 to 0.65 | 0.015 to 0.050 |
