High strength screw rod for oil drilling platform black 35CrMo 1.standard:DIN975 2.grade:12.9 3. ... material:35CrMo 4.black High strength screw rod for oil drilling platform black 35CrMo1.Standards:DIN ,ANSI/ASME,BS,GB,JIS,Non ... Korea,Southeast Asia ,etc. High strength screw rod for oil drilling platform black 35CrMo