In the building materials, the stainless steel round steel and the screw steel are the common forms of address for different kinds of steel bars. The difference between them is quite obvious, mainly five points.
The first is the difference in shape. The outer surface of the stainless steel round steel is very smooth, while the outer surface of the screw steel has a spiral rib. Secondly, the production standards of both are different. In the modern standard, stainless steel refers to HPB235 steel, the production standard is based on the “hot-rolled smooth steel reinforced concrete and steel”, usually refers to the HRB335 and HRB400 grade steel, the production standard is based on “the reinforcement of concrete hot rolled ribbed bar”.
The third point is that they are different in their strength. The design strength of stainless steel round steel is 210MPa, while the strength of rebar is higher than that of stainless steel round bar. The design strength of HRB335 is 300MPa, and the design strength of HRB400 is as high as 360MPa.
The fourth point is that the steel is different, that is to say, the chemical composition in the steel body is different. The stainless steel round carbon is carbon steel, the steel is Q235, the rebar is low alloy steel, the HRB335 grade reinforcement is 20MnSi (20 MN SI), and the HRB400 grade reinforcement is 20MnSiV or 20MnSiNb or 20MnTi.
It is because the chemical composition is different, so the physical and mechanical properties of the two are different. The better performance of cold-formed stainless steel, can hook 180, screw steel can be just 90 degrees straight hook, stainless steel weldability is good, as long as the use of ordinary carbon welding line, screw steel must use low alloy steel electrode; the toughness and anti fatigue properties etc. than the excellent stainless steel round bar.
Steel reinforced concrete is often used to build facilities, material is generally low alloy steel grades is generally 16Mn (16 Mn low-alloy steel), or 45 carbon just, yield strength are higher than 350Mpa, the tensile strength was less than 500Mpa, compared with the ordinary low carbon steel stainless steel round up very much, one thread the strength of the steel after heat treatment of the low carbon stainless steel round steel is nearly twice as high or even more. Because the surface has a thread shape, it can increase the bond with the concrete. The concrete member should choose the thread steel first with the longitudinal reinforcement and the stirrup.
So in general, because steel is a kind of low alloy steel, the price than the low carbon stainless steel round steel is high, the construction units from the ordinary civil construction of affordable angle positioning for reducing the quality of the project, will instead use low carbon stainless steel instead of steel. While some large key projects, usually in bribe related personnel, with stainless steel instead of steel rebar to “substitution”, so as to reduce the construction cost.
From the design perspective, because members without stirrups give principal stress support, the main role is to keep in shape and position, and because the stainless steel round bar surface is relatively smooth, the strapping easy positioning accuracy, so in addition to longitudinal reinforcement, can be used as a steel reinforced stainless steel round bar. But the longitudinal bar must be completely threaded steel.
Source: China Stainless Steel Pipes Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)