16Mn low-alloy tube: the strength divided into 300,350,400 and 450MPa four levels. Q295, Q345, Q390, Q420, Q460. : "Q" yield "Qu" Hanyu Pinyin caps head, followed by numbers for the grades minimum yield point value (sigma s), subsequent symbol is in accordance with the content of the steel impurity elements (sulfur, phosphorus) by high to low and accompanied by changes in the carbon, manganese is divided into A, B, C, D and so on. Where A, B grade steel commonly referred to 16Mn16Mn