What is the difference between the II and III grades of threaded steel?
Compared with traditional II grade steel, the characteristics are as follows:1, high corrosion resistance, can be a large number of security reserves.2. In the chemical composition, because of the low carbon equivalent of the new third grade steel, the welding performance is good.3, high strength ratio, meet the seismic performance requirements. Particularly suitable for high-rise buildings and high seismic performance requirements of the project.4, cold bending performance is good, can be repeatedly bent, more in line with and meet the construction requirements of the construction.5, because of the high strength, can reduce the use of steel, effectively solve the problem of reinforcing steel bars too close, easy to concrete pouring. At the same time, it also reduces the cost of steel transportation and on-site processing.
The difference between three grade steel and two grade steel can be divided into the following aspects:1, different grades of steel (chemical composition is different). HRB335 grade steel is 20MnSi (20 manganese silicon); HRB400 grade steel bars are 20MnSiV or 20MnSiNb or 20MnTi etc.;2, strength is different, HRB335 grade steel tensile and compressive design strength is 300MPa, HRB400 grade steel tensile and compressive design strength is 360MPa.3, because of the chemical composition of steel and the ultimate strength of different, so in toughness, cold bending, fatigue and other properties are also different.
Third grade rebar than ordinary II rebar strength increased about 20%, is designed for building construction of reinforced structure is developed, the yield strength of 400Mpa (grade HRB400), is the country to promote the use of excellent products.
