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Low-alloy steel plate Q235, ordinary carbon structural steel – plain steel, is a type of steel material. Q represents the yield strength of this material, while the 235 following it indicates that the yield value of this material is around 235. And its yield value decreases as the thickness of the material increases. Q235A，Q235B，Q235C，Q235D。 This is a distinction based on levels; what it represents is mainly the difference in impact temperature! What differs among A, B, C, and D is the impact temperature of their properties. They are respectively: Q235A grade, which does not require impact testing ； Grade Q235B: impact at 20 degrees Celsius ； Grade Q235C: impact at 0 degrees ； Grade Q235D: impact at -20 degrees Celsius. At different impact temperatures, the values of impact also vary. Element content: A, B, C, D; the sulfur content decreases in sequence ； A and B have the same phosphorus content; C has a lower phosphorus content, while D has the lowest phosphorus content. The chemical composition of various grades of Q235: Q235 is divided into four grades – A, B, C, and D (GB700-88). Grade Q235A contains 0.14–0.22% carbon, 0.30–0.65% manganese, Si ≤0.30%, S ≤0.050%, and P ≤0.045%. Grade Q235B contains 0.12–0.20% carbon, 0.30–0.67% manganese, Si ≤0.30%, S ≤0.045%, and P ≤0.045%. Grade Q235C contains ≤0.18% carbon, 0.35–0.80% manganese, Si ≤0.30%, S ≤0.040%, and P ≤0.040%. Grade Q235D contains ≤0.17% carbon, 0.35–0.80% manganese, Si ≤0.35%, S ≤0.040%, and P ≤0.035%. In terms of deoxidation methods, these can be represented by F, b, and z, referring to boiling steel, semi-killed steel, and killed steel respectively. Boiling steel is steel with incomplete deoxidation, and it has poor plasticity and toughness. Welded structures made of this material are prone to cracks at the joints under dynamic loads. It is not suitable for operation at low temperatures, and hardening may occur sometimes. In contrast, calm steel has excellent and uniform quality, with good plasticity and toughness. Mechanical properties of Q235: Tensile strength (σb/MPa): 375–500; Elongation (δ5/%): ≥26 (a≤16mm), ≥25 (a>16–40mm), ≥24 (a>40–60mm), ≥23 (a>60–100mm), ≥22 (a>100–150mm), ≥21 (a>150mm). Here, a represents the thickness or diameter of the steel material. Among sheet materials, it is the most common type and belongs to the ordinary sheet series. A previous name for it was: A3. Execution standards: The external standard is GB/T709-2006 \"Dimensions, shapes, weights and allowable tolerances of hot-rolled steel plates and strips\", while the internal standard is GB/T3274-2007 \"Hot-rolled thick steel plates and strips of carbon structural steel and low-alloy structural steel\". Classification categories: Performance, chemical composition, ordinary carbon structural steel, plain steel plates, low-alloy steel.