→GB/T1591-2018 low-alloy high-strength structural steel. GB/T1591-2018 modified the provisions on the mechanical properties of steel and the thickness interval, and defined the yield strength as the lower yield strength;The energy value of impact absorption was increased and the sampling site of impact test was clarified.GB/T1591-2018 applicable to low alloy and high strength structural steel plates, steel belts, sections and bars for general structure and engineering.