Abstract：According to the requirements on metallographic structure of hot rolled ribbed steel bar in No.1 amendment XG1-2009 of GB1499.2-2007, the physicochemical properties of two groups of 400-grade hot rolled ribbed steel bars (without difference on outward appearance) from different production process were tested. It was found that their metallographic structures were different. The feasibility analysis of metallographic structure evaluation was conducted from the chemical elements, the mechanical property and welding performance of steel bar. The definition of XG1-2009 expression and the operability of implementation were discussed.
