Information of Properties, Composition & Equivalent of Q355 Steel, Q355B Q355C Q355D

Q355 steel is a new Chinese steel grade of Low Alloy High Strength Structural Steel, which replaced Q345, the material density is 7.85 g/cm3. According to GB/T 1591-2018, Q355 has 3 quality levels: Q355B, Q355C and Q355D. “Q” is the first letter of Chinese Pinyin: “qu fu dian”, which means Yield Strength, “355” is short for 355 MPa, parameters are tested with 16mm diameter steel bars or steel plates, and tensile strength is 470-630 Mpa.

Q355 Features and Applications

Q355 steel has good mechanical properties, good weldability, hot and cold processing properties and corrosion resistance. Can be used to manufacture ships, boilers, pressure vessels, petroleum storage tanks, bridges, power station equipment, lifting transport machinery and other higher load welded structural parts.

Q355 Steel Chemical Composition (Hot rolled)

Steel Grade

Quality Grade

C % (≤)

Si % (≤)

Mn (≤)

P (≤)

S (≤)

Cr (≤)

Ni (≤)

Cu (≤)

N (≤)

Mo (≤)

B (≤)

Nb (≤)

V (≤)

Ti (≤)

Q355

Q355B

0.24

0.55

1.6

0.035

0.30

0.40

0.012

–

Q355C

0.20

0.030

0.012

Q355D

0.20

0.025

–

Carbon Equivalent (CEV)

Based on smelting analysis, steel delivered in hot rolled state

		CEV (Mass fraction ≤%); Nominal thickness or diameter Ø
Steel Grade	Quality Grade	≤ 30	30 < Ø ≤ 63	63 < Ø ≤ 150	150 < Ø ≤ 250	250 < Ø ≤ 400
Q355	Q355B	0.45 (CEV)	0.47	0.47	0.49	–
	Q355C					–
	Q355D					0.49

Q355 Mechanical Properties (Hot rolled)

		Thickness or Dia. (Ø) mm; Yield Strength (≥N/mm2)
Steel Grade	Quality Level	Ø≤16	16< Ø ≤40	40 < Ø ≤63	63 < Ø ≤ 80	80 < Ø ≤ 100	100 < Ø ≤ 150	150 < Ø ≤ 200	200 < Ø ≤ 250	250 < Ø ≤ 400
Q355	Q355B	355	345	335	325	315	295	285	275	–
	Q355C									–
	Q355D									265

		Dia. (Ø) mm; Tensile Strength (N/mm2)
Steel Grade	Quality Level	Ø≤100	100 < Ø ≤ 150	150 < Ø ≤ 250	250 < Ø ≤ 400
Q355	Q355B	470 – 630	450 – 600	450 – 600	–
	Q355C				–
	Q355D				450 – 600

Q355 Steel Elongation

	Dia. (Ø) mm; Elongation (%)
Sample direction	Ø≤40	40 < Ø ≤ 63	63 < Ø ≤ 100	100 < Ø ≤ 150	150 < Ø ≤ 200	250 < Ø ≤ 400
Horizontal	20	19	18	18	17	17
Vertical	22	21	20	18	17	17