不是越贵越好：Q355 强度高 33%，但用错地方反而浪费钱。一张表看懂怎么选。Higher grade isn't automatically better. Q355 is 33% stronger — but in the wrong place it just wastes money.
Q235B 与 Q355B 的屈服强度分别是 235MPa 与 355MPa，差 33%。但选材不是「买强的」，而是一道算术题：
主受力构件（刚架梁柱、吊车梁）：高应力区域用 Q355 通常能减薄板厚 8%–15%，钢材省下的钱足以覆盖价差，多数项目划算。
次要构件（檩条、墙梁、隅撑）：截面往往由稳定性和构造要求控制而非强度，用 Q355 一点强度余量都发挥不出来，纯浪费。
连接件与节点板：牌号要与被连接构件匹配，混用会引起焊接工艺复杂化。
另外注意：出口项目如果业主要求欧标，Q355B 可对应 S355JR，但冲击韧性试验温度（B 级 = 20℃）要按项目环境确认，寒冷地区需选 C/D 级。雄岚报价默认给出主次构件的牌号建议与成本对比。
Q235B and Q355B yield at 235MPa and 355MPa — 33% apart. But grade selection isn't “buy the strongest”; it's arithmetic:
Primary members (frames, crane girders): in high-stress zones Q355 can slim plates by 8–15%, and the steel saved usually outweighs the price premium — worthwhile on most projects.
Secondary members (purlins, girts, knee braces): their sections are governed by stability and detailing, not strength — Q355 adds nothing there but cost.
Connections and gussets: match the grade of the connected members; mixing grades complicates welding.
For export projects under Eurocode: Q355B corresponds to S355JR, but confirm the impact-test temperature (grade B = +20°C) against site climate — cold regions need grade C or D. Xionglan quotes always include grade recommendations and cost comparisons for primary vs secondary steel.
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