According to GB/T 1591 2008, Q345 material has 5 quality gradesQ345A, Q345B, Q345C, Q345D and Q345E. GB/T1591 - steel-plate-sheetsgb/t1591 Main Application Carbon and Low-alloy High-strength Steel Plate is Widely Used In Construction of Bridges, Riveted, Bolted, And Other Structural Elements Included Drilling Machine, Power Shovel, Electricity gb t1591 q345b chemical composition(plate) Equivalent steel grades bs en S355JR VS Q355B-C H I D gb t1591 q345b chemical composition(steel) Equivalent steel grades bs en S355JR+AR VS Q345B.Q345B is a new steel grade in latest version chinese steel standard GB/T1591-2008,before this version.S355JR+AR hot rolled steels from European British steel standard BS EN10025-2 low alloy high strength steels.These two steel materials Q345B and S355JR+AR are totally equivalent in chemical gb t1591 q345b chemical composition(plate) Some results are removed in response to a notice of local law requirement. For more information, please see here.