Chemical element composition of Chinese grade hot-rolled or normalized bridge steel Q550qD
Q550qD Similar Grade Lookup Table

Table 1  Chemical composition of tempered steel

Grade Quality
grade		 Chemical Composition(Quality Fraction)/%
C Si Mn Nbᵃ Vᵃ Tiᵃ Alsᵃ,ᵇ Cr Ni Cu Mo N
≤
Q550q D 0.12 0.55 0.80~
1.70		 0.005~
0.060		 0.010~
0.080		 0.006~
0.030		 0.010~
0.045		 ≤0.80 ≤0.70 ≤0.30 ≤0.30 ≤0.0080
Note: Element B can be added at a rate of 0.0005% to 0.0030%.
a:Al, Nb, V, and Ti can be added to steel individually or in combination. When added individually, they should comply with the provisions in the table. When added in combination, at least one alloying element should be added at the lower limit specified in the table, and the content of Nb+V+Ti should be less than 0.22%.
b:When using total aluminum (Alt) content for calculation, the total aluminum content should be 0.015%~0.050%.

Table 2  Mechanical properties of steel

Grade Quality grade Tensile testᵃ,ᵇ Impact testᶜ
Lower yield strength ReL/MPa Tensile strength
Rm/MPa		 Elongation after fracture
A/%		 Temperature℃ Impact absorption energy
KV2/J
Thickness≤50mm 50mm<Thickness≤100mm 100mm<Thickness≤150mm
≥ ≥
Q550q D 550 530 — 660 16 -20 120
a:When the yield strength is not obvious, Rp0.2 can be measured instead of the lower yield strength.
b:For tensile tests, transverse specimens are taken.
c:Longitudinal specimens are used for impact testing.