• Q345C Steel Properties and Introduction
  • Q345C Steel Properties and Introduction

    Q345C steel is a Chinese GB standard Low Alloy High Strength Structural Steel, material density is 7.85 g/cm3, tensile strength is 470-630 Mpa, and yield strength is 345 MPa (datasheet tested with 16mm diameter steel bars or steel plates). According to GB/T 1591 – 2008, Q345 material has 5 quality grades: Q345A, Q345B, Q345C, Q345D and Q345E. “Q” is the first letter of Chinese Pinyin: “qu fu dian”, which means Yield Point, “345” is short for 345 MPa. For datasheet and specification, please see the tables below.

    Q345 steel weldability, cold & hot workability and corrosion resistance are good. Widely used in bridges, ships, boilers, pressure vessels, petroleum storage tanks, lifting transport machinery and other high-load welded structural parts.

    Table-1, Chemical Composition of Q345C Steel
    Chemical Composition Content (≤%) ≥%
    Steel Grade Quality Grade C Si Mn P S Nb V Ti Cr Ni Cu N Mo B Als
    Q345 Q345A 0.20 0.50 1.70 0.035 0.035 0.07 0.15 0.20 0.30 0.50 0.30 0.012 0.10
    Q345B 0.035 0.035
    Q345C 0.030 0.030 0.015
    Q345D 0.18 0.030 0.025
    Q345E 0.025 0.020

    Notes: The P and S contents of profiles and bars can be increased by 0.005%, and the upper limit of Grade A steel can be 0.0045%.

    Table-2, Q345 Mechanical Properties

    Mechanical Properties: Yield Strength (≥ N/mm2)
    Steel Grade Quality Grade 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
    Q345 Q345A ≥345 ≥335 ≥325 ≥315 ≥305 ≥285 ≥275 ≥265
    Q345B
    Q345C
    Q345D ≥265
    Q345E

    Notes: Ø = Thickness or wire diameter in mm;

    1 MPa = 1 N/mm2

    Mechanical Properties: Tensile Strength (N/mm2)
    Grade Quality Level Ø ≤ 40 40 < Ø ≤ 63 63 < Ø ≤ 80 80 < Ø ≤ 100 100 < Ø ≤ 150 150 < Ø ≤ 250 250 < Ø ≤ 400
    Q345 Q345A 470 – 630 470 – 630 470 – 630 470 – 630 450 – 600 450 – 600
    Q345B
    Q345C
    Q345D 450 – 600
    Q345E
    Ø mm, Elongation (≥%)
    Grade Quality Level Ø ≤40 40 < Ø ≤ 63 63 < Ø ≤ 100 100 < Ø ≤ 150 150 < Ø ≤ 250 250 < Ø ≤ 400
    Q345 Q345A ≥20 ≥19 ≥19 ≥18 ≥17
    Q345B
    Q345C ≥21 ≥20 ≥20 ≥19 ≥18
    Q345D ≥17
    Q345E

    Q345 Equivalent

    Q345 steel: Q345A, Q345B, Q345C, Q345D, Q345E equivalent to US ASTM, European Germany DIN, British BS, France NF, Japan JIS, and ISO Standard (For Reference)

    Q345 Equivalent
    China USA Germany Japanese France UK ISO
    Standard Grade Standard Grade Standard Grade (steel number) Standard Grade Standard Grade (steel number) Standard Grade (steel number) Standard Grade
    GB/T 1591 – 2008 (Year) Q345A ASTM A529/A529M;
    ASTM A572/A572M;
    ASTM A588/A588M;
    ASTM A678/A678M;
    ASTM A808/A808M
    Grade 50;
    Grade 50;
    Grade B;
    Grade D;
    A808M
    DIN EN 10025-2;

    DIN 17100

    S355JR (1.0045),
    E355 (1.0060);
    St52-3
    JIS G3135 SPFC590 NF EN 10025-2 S355JR (1.0045),
    E355 (1.0060);
    BS EN 10025-2 S355JR (1.0045),
    E355 (1.0060);
    ISO 630-2 S355C, S355D (S355)
    GB/T 1591 – 2008 Q345B Ditto Ditto Ditto Ditto JIS G3135 SPFC 590 Ditto Ditto Ditto Ditto ISO 630-2 S355C, S355D (S355)
    GB/T1591 – 2008 Q345C Ditto Ditto DIN EN 10025-2;
    DIN 17100
    S355J0 (1.0553),
    E335 (1.0060);
    St52-3
    JIS G 3135 SPFC590 NF EN 10025-2 S355JO (1.0553),
    E335 (1.0060)
    BS EN 10025-2 S355JO (1.0553),
    E335 (1.0060)
    ISO 630-2 S355D (S355)
    GB/T 1591 – 2008 Q345D ASTM A656/A656M;

    ASTM A529/A529M

    Type 7;

    Grade 50

    DIN EN 10025-2;
    DIN EN 10025: 1993;
    DIN 17100
    S355J0 (1.0553),
    E335 (1.0060);
    S355J2G3 (1.0570);
    St52-3
    JIS G 3135 SPFC590 NF EN 10025-2;
    NF EN 10025: 1993
    S355J0 (1.0553),
    E335 (1.0060);
    S355J2G3 (1.0570)
    BS EN 10025-2;
    BS EN 10025: 1993
    S355J0 (1.0553),
    E335 (1.0060);
    S355J2G3 (1.0570)
    ISO 630-2 S355D (S355)
    GB/T 1591 – 2008 Q345E ASTM A656/A656M;

    ASTM A529/A529M

    Type 7;

    Grade 50

    DIN EN 10025-2;
    DIN EN 10025: 1993
    S355J2 (1.0553),
    S355K2 (1.0596),
    E335 (1.0060);
    S355J2G4 (1.0577),
    S355K2G3 (1.0595),
    S355K2G4 (1.0596)
    JIS G3135 SPFC 590 NF EN 10025-2;
    NF EN 10025: 1993
    S355J2 (1.0553),
    S355K2 (1.0596),
    E335 (1.0060);
    S355J2G4 (1.0577),
    S355K2G3 (1.0595),
    S355K2G4 (1.0596)
    BS EN 10025-2;
    BS EN 10025: 1993
    S355J2 (1.0553),
    S355K2 (1.0596),
    E335 (1.0060);
    S355J2G4 (1.0577),
    S355K2G3 (1.0595),
    S355K2G4 (1.0596)

    Notes: Q345 steel has been replaced byQ355 in the latest version of GB standard “GB/T 1591 – 2018”, the previous version is “GB/T 1591 – 2008”.