280 is a low-carbon micro-alloyed steel containing vanadium. Its yield strength is significantly higher than for regular structural steels such as S355. In spite of this higher strength, impact toughness and weldability remain acceptable and the steel is relatively easy to machine.
280 conforms closely to the steel S450J0 as standardised in SS-EN 10025 - 2. It is also very similar to the grade 19MnVS6 in the standard SS-EN 10267. The (discontinued) SS-designation is 2142. On tensile testing, the lowest allowed yield strength for 280 is in the interval 520 - 400 MPa dependent on diameter. For a bar with given diameter, 280 has about 150 MPa higher yield strength than S355J2.
The diameter tolerance for ground bars in grade 280 is excellent, level h6 as defined in ISO 286 - 2. The surface finish expressed in terms of Ra is 0.6 µm or better. The bars are also very straight with the maximum height of arc being 0.0001 times the bar length.
The weldability of 280 is good and its carbon equivalent is 0.55% or less. Welding without preheat is then feasible unless the diameter of the part is >80 mm. Thanks to a controlled level of sulphur, machinability is reasonably good especially when compared with S355J2.
If the application requires that the part has a wear-resistant surface, 280 responds well to both case hardening and nitriding. Furthermore, its strength can be increased via quenching and tempering provided cooling during hardening is fast enough (preferably in water or polymer quenchant).