The chemical composition of Q235C steel pipe mainly includes carbon (C), silicon (Si), manganese (Mn), phosphorus (P), and sulfur (S), among which the carbon content is ≤0.18%, the silicon content is ≤0.35%, the manganese content is ≤0.80%, and the phosphorus and sulfur contents are ≤0.040% and 0.040% respectively. Compared with Q235A and Q235B, Q235C has lower phosphorus and sulfur content, which improves the low-temperature toughness of the material. In addition, Q235C may also contain trace amounts of copper (Cu), chromium (Cr), nickel (Ni) and other elements, but the content is low, which mainly affects welding performance and corrosion resistance.
Q2: What are the mechanical properties of Q235C steel pipe?
The yield strength of Q235C steel pipe is ≥235MPa, the tensile strength is between 375-500MPa, and the elongation after fracture is ≥26%. Its impact toughness is required to be ≥27J at 0℃, which is higher than Q235A and Q235B and is suitable for low temperature environments. In addition, the hardness of Q235C is usually between HB120-160, and the specific value depends on the heat treatment state. Due to its good plasticity and toughness, Q235C steel pipes are suitable for building structures, machinery manufacturing and other fields.
Q3: What temperature range is Q235C steel pipe suitable for?
Q235C steel pipes are suitable for environments from -20℃ to +300℃. Compared with Q235A (no impact requirement) and Q235B (20℃ impact requirement), Q235C has better low temperature performance. In an environment below -20℃, its toughness will decrease and brittle fracture may occur, so it is not recommended for use in extremely cold areas. At high temperatures (>300℃), the strength of Q235C will gradually decrease, and the creep effect needs to be considered for long-term use. Therefore, Q235C is often used for structural parts in normal temperature or low temperature (but not extreme) environments.
Q4: What are the implementation standards of Q235C steel pipe?
The main implementation standards of Q235C steel pipe include GB/T 700 (carbon structural steel), GB/T 3091 (welded steel pipe), and GB/T 8162 (seamless steel pipe for structure). Among them, GB/T 3091 is applicable to welded steel pipes for low-pressure fluid transportation, while GB/T 8162 is applicable to seamless steel pipes for general structure. In addition, Q235C can also be used for GB/T 6728 (cold-bent hollow steel for structure) and other standards. Different standards have different requirements for the size, mechanical properties, and process of steel pipes, which need to be selected according to specific uses.
Q5: What is the difference between Q235C and other Q235 grades (A/B/D)?
The main differences between Q235A, Q235B, Q235C, and Q235D are impact toughness and phosphorus and sulfur content. Q235A has no impact requirement, Q235B requires 20℃ impact ≥27J, Q235C requires 0℃ impact ≥27J, and Q235D requires -20℃ impact ≥27J. In addition, the phosphorus and sulfur content decreases in sequence (Q235A is the highest and Q235D is the lowest), making Q235D the best in purity and low-temperature performance. Therefore, Q235C is suitable for medium-low temperature environments, while Q235D is suitable for more severe low-temperature conditions.
