| Abstract: | A high strength structure steel plate --brand JG785E, which with more than 690MPa yield strength ,more than 47 joules toughness at minus 40℃ has been developed by Jigang of Shandong Steel Group P. R. China. The steel plates can be easily welded in engineering structure due to its lower carbon equivalent value. The maximum thickness of heavy plate is 50.88mm (2 inch), the yield strength is 710-860MPa, the toughness of steel plate is 139~336J at the temperature of - 40℃ . The microstructure of steel plate is lower carbon Bainite. The main solid dissolve elements are silicon and manganese. All parameters of reheating, rolling and accelerating cooling are controlled strictly. This TMCP procedure can ensure to get better mechanical properties of steel plates, and to keep the market competitive power and lower cost of manufacture. The cleanness of steel is high by refined in ladle furnace (LF), the contents of P and S is lower. It is the low carbon Bainite microstructure that possesses the high strength, excellent lower temperature toughness and better weld-ability without preheat process. The JG785E is typical brand of the Jigang’s high strength steel brands as the S690QL conforms to EN10025-6 and as the ASTM A514M conforms to USA quenching and tempering steel specification. |
