Some Issus on Application for New National Standard GB/T 1591-2018 High Strength Low Alloy Structural Steel

The new revised national standard GB/T 1591-2018 High Strength Low Alloy Structural Steel was implemented in February, 2019. This revision made many important changes and additiongs, optimized the performamce of steel.
Such changes include steel lower yield change to upper yield strength,strengthenes alloy composition,adds products classification by different rolling processes, such as hot rolling, normalizing and thermomechanical rolling. According to different rolling process, optimized the steel strength index and quality grades, the A grade steel was cancelled. According to different grades and thickness, the quaranteed limits for longitudinal and transverse elongation, impact energy and Carbon equivalent (C_EV) index are also specified respectively. Meanwhile, the product thickness are expanded in a large range, the maximum thickness can be 250 mm(for hot rolled and normalized steel) or 120 mm(for thermomechanically rolled steel). Over and above, steel grades and thickness classification are consisted with Europran standards, adapt the needs of overseas projects.
This paper compares and explains the above changs in detail, and gives some suggestions for reasonable selection of steel signal, rolling process categories, quality grades, performance index, etc. Finally, suggests the revised steel strength design values for structural design.