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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”.

Q345C Steel Properties and Introduction Equivalent Material:

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