The three stage of the steel is the most widely used steel, its application is very wide, in the bridge, housing, roads and other aspects of the use of a large number of concrete and beam column in the main reinforcement of the application of more. And the two grade of steel (HRB335) is used in the subway project, its yield strength and tensile strength and other mechanical properties are not as good as the grade three screw thread, the country is gradually out of the grade two screw steel.

      Compared with the four grade screw steel (HRB500), although the performance of the three grade rebar will be worse, but the price is higher, and for most of the engineering, construction requirements can be met.