What is thread steel for?
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.
1. nominal diameter range and recommended diameterThe nominal diameter of the thread steel is from 6 to 25mm, and the nominal diameter of the standard steel is 6, 8, 10, 12, 14, 16, 20, 25,, 32, 40 and 50mm.Allowable deviation of surface shape and dimension of 2. ribbed steel discThe ribbed steel bars with ribbed threads shall meet the following basic requirements:The angle between the transverse ribs and the axis of the steel disc should not be less than 45 degrees. When the angle is not greater than 70 degrees, the direction of the cross section of the thread steel is opposite to that of the upper rib on both sides;The transverse rib and the spacing l shall not be greater than 0.7 times the nominal diameter of the steel;The angle between the sides of the transverse rib and the surface of the threaded steel shall not be less than 45 degrees;The sum of the gap (including the width of longitudinal ribs) between the ends of the cross bar and the end of the cross bar of the threaded steel shall not be greater than 20% of the nominal circumference of the thread steel;When the rebar nominal diameter less than 12mm, the relative rib area should not be less than 0.055; the nominal diameter of 14mm and 16mm, the relative rib area should not be less than 0.060; the nominal diameter is more than 16mm, the relative rib area should not be less than 0.065.
Three rebar is the new standard name for HRB400 steel, three steel for the old, as a kind of hot rolled ribbed bar. In construction, three - grade rebar is called the past.
