Q355 Steel, Q355B Q355C Q355D Properties, Composition & Equivalent

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Q355 Steel Introduction

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 the minimum value of yield strength 355 MPa for steel thickness ≤16mm, and tensile strength is 470-630 Mpa.

Datasheet and Specification

Table-1, Q355 Steel Chemical Composition (Hot rolled)

Steel GradeQuality GradeC % (≤)Si % (≤)Mn (≤)P (≤)S (≤)Cr (≤)Ni (≤)Cu (≤)N (≤)Mo (≤)B (≤)Nb (≤)V (≤)Ti (≤)

Table-2, Carbon Equivalent (CEV)

Based on smelting analysis, steel delivered in hot rolled state

CEV (Mass fraction ≤%); Nominal thickness or diameter Ø
Steel GradeQuality Grade≤ 3030 < Ø ≤ 6363 < Ø ≤ 150150 < Ø ≤ 250250 < Ø ≤ 400
Q355Q355B0.45 (CEV)0.470.470.49

Table-3, Q355 Mechanical Properties (Hot rolled)

Thickness or Dia. (d) mm; Yield Strength (≥N/mm2)
Steel GradeQuality Leveld≤1616< d ≤4040 < d ≤6363 < d ≤ 8080 < d ≤ 100100 < d ≤ 150150 < d ≤ 200200 < d ≤ 250250 < d ≤ 400
Dia. (d) mm; Tensile Strength (N/mm2)
Steel GradeQuality Leveld≤100100 < d ≤ 150150 < d ≤ 250250 < d ≤ 400
Q355Q355B470 – 630450 – 600450 – 600
Q355D450 – 600

Table-4, Q355 Steel Elongation

Dia. (d) mm; Elongation (%)
Sample directiond≤4040 < d ≤ 6363 < d ≤ 100100 < d ≤ 150150 < d≤ 200250 < d ≤ 400

Charpy Impact

Charpy (V-notch) impact test temperature and impact absorption energy (KV2/J).

QualityTemperatureLongitudinal Impact Energy (J), ≥Transverse Impact Energy (J), ≥
Q355B20 ℃3427
Q355C0 ℃3427
Q355D-20 ℃34 (for thickness ≥250mm)27 (for thickness ≥250mm)

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.

Table-5, Q355 Steel Equivalent Grade (Reference)

GB/T 1591 -2018Q355BISO 630-2S355BEN 10025-2 :2004S355, S355JR

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  1. Jay Gordon says

    Do you know where I can purchase Chinese steel specifications in the United States?
    Q355 in particular.

  2. Kawashima says


    What is the JIS equivalent of Q355 in Japan?

    1. World Material says

      Hi, it seems that Q355 has no equivalent to Japanese steel grade, you can try to compare with SPFC 590 under JIS G3135 (Cold-reduced high strength steel sheet and strip with improved formability for automobile structural uses)

  3. JW Kim says

    Which standard does the grade, SM335B belong to? And if you have the information, what is the density of the material for this standard, the yield strength and tensile strength ? Thank you.

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