This type of steel mainly ensures mechanical properties. Therefore, its grade reflects its mechanical properties and is represented by Q+ numbers, where “Q” is the yield point and the prefix of the Chinese pinyin of “Qu”. The numbers indicate the yield point value. For example, Q275 indicates that the yield point is 275Mpa. If the letters A, B, C, and D are marked after the grade, it means that the quality of the steel is different. The content of S and P decreases in sequence and the quality of the steel increases in sequence. If the letter “F” is marked after the grade, it is boiling steel, if it is marked “b”, it is semi-killed steel, and if it is not marked “F” or “b”, it is killed steel. For example, Q235-AF represents Grade A boiling steel with a yield point of 235MPa, and Q235-C represents Grade C killed steel with a yield point of 235MPa.
Carbon structural steel is generally not heat treated and is used directly as supplied. Generally, Q195, Q215, and Q235 steels have low carbon mass fraction, good welding performance, good plasticity and toughness, and a certain strength. They are often rolled into thin plates, steel bars, welded steel pipes, etc. Used in bridges, buildings, and other structures and the manufacture of ordinary rivets, screws, nuts, and other parts. Q255 and Q275 steels have a slightly higher carbon mass fraction, higher strength, better plasticity, and toughness, and can be welded. They are usually rolled into shaped steel, bar steel, and steel plates for structural parts and manufacturing connecting rods, gears, and couplings of simple machines. Sections, pins, and other parts.
