What is the yield strength of Q235 steel?
4 Answers
Q235 has a yield strength of 235MPa. Q235 ordinary carbon structural steel is also called A3 plate. Ordinary carbon structural steel - ordinary plate is a type of steel material. The Q represents the yield limit of this material, and the following 235 refers to the yield value of this material, which is around 235MPa. The yield value decreases as the thickness of the material increases (plate thickness/diameter ≤16mm, yield strength is 235MPa). Below are the usage introductions: 1. Widely used in construction and engineering structures: used to make steel bars or construct factory building frames, high-voltage transmission towers, bridges, vehicles, boilers, containers, ships, etc. It is also widely used as mechanical parts with relatively low performance requirements. C and D grade steel can also be used for certain professional steel applications. 2. Used for various mold handles and other non-critical mold parts.
We commonly use Q235 steel on construction sites. Experienced welders all know its yield strength is standardized at 235 MPa. This strength value represents the critical point where the material begins to deform - below this threshold, it can return to its original shape. When actually designing steel structures, this number is fundamental for calculating the load-bearing capacity of columns and beams. However, note that steel plate thickness affects actual performance. For instance, new thin plates within 12mm generally test at 235 MPa, while extra-thick 40mm plates may drop to 225 MPa. Just last week, a new intern calculating factory support structures used this 235 MPa value with a 1.67 safety factor.
Having worked in structural design for over a decade, Q235 yield strength is something I encounter daily. The national standard GB/T 700 clearly states it's 235 MPa, but practical applications require differentiation: for 20 mm thick steel plates at room temperature, a distinct plateau must appear in the tensile test curve to count. The same standard value applies to HPB235-labeled rebar, though I always remind young engineers that the tensile design value in reinforced concrete is set at 210, leaving a safety margin. Last time, the inspection report showed an on-site sample tested at 241, which was perfectly acceptable - the only requirement is not falling below the nominal value.
Here's a detail from material testing: When Q235 steel bars are sent to the lab for yield strength testing, we mainly look at two indicators. The lower yield strength ReL is the most commonly used value, which is 235 MPa. However, for materials with significant deformation like cold-formed steel sections, we also need to measure the strength value corresponding to the Rp0.2 residual deformation. These two values typically fluctuate between 225-245 MPa. Last time we tested a batch of angle steels, the measured ReL was 238 MPa, just within the national standard's allowable lower limit of 245 MPa. If the temperature drops below zero, this value can increase by about 10%.
