The difference between the third-grade steel bar and the second-grade steel bar in the rebar welding

In the construction industry, Grade II steel bars and Grade III steel bars are the former (old standard). In the new standard, Grade II steel bars are renamed HRB335 grade steel bars, and Grade III steel bars are renamed HRB400 grade steel bars.
What is the difference between the third-grade steel and the second-grade steel in the reinforced steel welding?

In the construction industry, Grade II steel bars and Grade III steel bars are the former (old standard). In the new standard, Grade II steel bars are renamed HRB335 grade steel bars, and Grade III steel bars are renamed HRB400 grade steel bars.
To put it simply, the same points of the two types of steel bars are: ordinary low-alloy hot-rolled steel bars; all belong to ribbed steel bars (so-called threaded steel bars); they can all be used in ordinary reinforced concrete structures.
The main differences are:
1. Different steel grades (different chemical composition). HRB335 grade steel bar is 20MnSi (20 manganese silicon); HRB400 grade steel bar is 20MnSiV or 20MnSiNb or 20MnTi;
2. The strength is different. The tensile and compressive design strength of HRB335 steel bars is 300MPa, and the tensile and compressive design strength of HRB400 steel bars is 360MPa.
3. Due to the difference in chemical composition and ultimate strength of steel bars, there are also differences in properties such as toughness, cold bending, and fatigue resistance.
The theoretical weight of the two bars is the same when the nominal diameter and length are equal.
The requirements for the anchor length of the two types of steel in concrete are different. The anchorage length of the steel bar is related to the tensile strength of the steel bar, the tensile strength of the concrete and the shape of the steel bar. Tell you a formula: the anchor length of the tensile reinforcement in concrete is L = a × (f1/f2) × d. Where f1 is the tensile design strength of the steel bar; f2 is the tensile design strength of the concrete; a is the shape factor of the steel bar, the smooth steel bar is 0.16, the ribbed bar is 0.14; d is the nominal diameter of the steel bar. In addition, when the steel bar is HRB335 and HRB400 with a diameter greater than 25mm, the anchor length should be multiplied by a correction factor of 1.1. In the seismic zone, a factor greater than one should be multiplied according to the seismic level.
The anchorage length of the compressed steel in the concrete is 0.7 times the anchorage length of the tensile reinforcement.
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