Chemical element composition of Chinese grade Q355MB low alloy high strength structural steel

Current manufacturing execution standard:GB/T 1591-2018
Q355MB Similar Grade Lookup Table

Table 1  Chemical Composition

Grade Chemical Composition(Quality Fraction) / %
Steel grade Quality grade C Si Mn Pᵃ Sᵃ Nb V Tiᵇ Cr Ni Cu Mo N B Alsᶜ≥
≤
Q355M B 0.14ᵈ 0.5 1.6 0.035 0.035 0.01~0.05 0.01~0.1 0.006~0.05 0.3 0.5 0.4 0.1 0.015 - 0.015
The steel should contain at least one of the grain-refining elements such as aluminum, niobium, vanadium, and titanium. When added alone or in combination, the content of at least one alloying element should not be less than the lower limit specified in the table.
a.For structural steel and bars, the phosphorus and sulfur content can be increased by 0.005%.
b.It can be as high as 0.2%.
c.All-aluminum (Alt) can be used as a substitute, in which case the minimum all-aluminum content is 0.02%. When grain-refining elements such as niobium, vanadium, and titanium are added to the steel and their content is not less than the lower limit specified in the table, there is no limit to the lower limit of aluminum content.
d.For structural steel and bars, the maximum carbon content of Q355M, Q390M, Q420M and Q460M can be increased by 0.02%.

Table 2  Tensile properties

Grade Upper yield strength ReHᵃ/MPA≥ Tensile strengthRｍ/MPA Elongation after fracture A／％
≥		 KV2(J)
Steel grade Quality  grade Nominal thickness or diameter/ｍｍ 20℃
≤16 ＞16~40 ＞40~63 ＞63~80 ＞80~100 ＞100~120 ≤40 ＞40~63 ＞63~80 ＞80~100 ＞100~120ᵇ Vertical Horizontal
Q355M B 355 345 335 325 325 320 470~630 450~610 440~600 440~600 430~590 22 34 27
Note: Thermomechanically rolled (TMCP) condition includes thermomechanically rolled (TMCP) + tempered condition.
a.When the yield strength is not obvious, the specified plastic elongation strength Rp0.2 can be used instead of the upper yield strength ReH.
b.For structural steel and bar stock, the thickness or diameter shall not exceed 150 mm.