How do EN standards define round steel dimensions?

EN 10083-1 (Hot-rolled non-alloy steels for quenching and tempering) and EN 10277-1 (Bright steel products) define round steel dimensions. Key specs include diameter (d) – EN 10083-1 covers 5mm to 300mm for hot-rolled round steel, with common sizes like 10mm, 25mm, 80mm. Tolerance classes are critical: EN 10083-1 specifies h11 (loose tolerance, ±0.13mm for 20mm diameter) for general use, and h9 (tighter, ±0.087mm) for precision applications. Length standards range from 3m to 12m for hot-rolled round steel, with custom lengths (up to 18m) available for a 1-week lead time extension. EN 10277-1 adds bright round steel dimensions (diameters 3mm to 100mm) with stricter tolerances (h8, ±0.052mm for 20mm) for components like bearings. These dimensions ensure compatibility with European manufacturing and construction, where precision assembly is key.