SS400 structural steel is composed of iron, phosphorus and sulphur. It contains a maximum of 0.05 percent phosphorus and 0.05 percent sulphur. JIS G 3101 is the standard that defines the chemical composition of SS400 structural steel; it is Japanese in origin.
Engineers use SS400 steel for general structural usage in the form of hot rolled steel plates, sheets and strips. SS400 exhibits a tensile strength between 400 and 510 newtons per square millimeter, which is greater than that of its closest relative, SS330 steel. The yield strength of SS400 steel is between a minimum of 205 and 245 newtons per square millimeter.
Engineers and metallurgists use SS400 structural steel for a variety of applications, including the creation of structural tubes, pipes, rods and sectional sheets for construction. JIS G 3101 defines the applicable thickness of SS400 steel as being between 6 millimeters and 120 millimeters. The thickness of a particular sheet of SS400 steel affects its yield strength and its elongation properties. SS400 steel exhibits a minimum elongation property of 17 percent at a thickness up to 16 millimeters, 21 percent at a thickness between 16 and 40 millimeters, and 23 percent at a thickness of more than 50 millimeters due to its chemical composition.