Q: What is the hardness range of Q355D steel plate?
A: Brinell hardness (HBW) is generally ≤217. There is no mandatory standard requirement; it is only a reference indicator. Excessive hardness will affect weldability and cold workability.
Q: How much will the yield strength of Q355D decrease when the thickness is greater than 100mm?
A: The yield strength is ≥305MPa for thicknesses of 100~150mm, and ≥295MPa for thicknesses of 150~200mm. The yield strength decreases slightly with increasing thickness.
Q: What are the core alloying elements of Q355D?
A: The main alloying element is Mn (manganese), with Si (silicon) added as a secondary alloying element. Some steel mills may add trace amounts of Nb (niobium), V (vanadium), and Ti (titanium) to refine the grain and improve strength and toughness.
Q: What is the upper limit of carbon (C) content in Q355D?
A: Carbon content ≤0.20%. Low-carbon design ensures weldability and low-temperature toughness, avoiding embrittlement caused by excessive carbon content.
Q: What are the strict requirements for the sulfur (S) and phosphorus (P) content of Q355D?
A: S≤0.015%, P≤0.025%, which is a low-sulfur, low-phosphorus low-alloy steel plate, effectively reducing segregation and brittle defects.