GB / T4171 standard specifies the definition, size, shape, technical requirements, test methods, acceptance rules and packaging, marking, quality certificate, etc. of the high weather resistant structural steel. The GB / T4171 standard is suitable for hot- Rolled steel, steel and steel. Vehicles, containers, construction, towers and other structural parts are usually used in the delivery state, can be made bolted, riveting and welding of structural parts.GB/T4171 standard main steel grade:Q500NH,Q550NH,Q415NH,Q355NH,Q295NH,Q310GNH and so on.