Q345B steel polishing method

Q345b steel polishing method often used Polishing means a processing method by the action of mechanical, chemical or electrochemical, lower the q345b steel pipe surface roughness

Polishing means a processing method by the action of mechanical, chemical or electrochemical, lower the q345b steel pipe surface roughness, to obtain a bright and smooth surface, and surface modification process making use of a flexible polishing tools and polishing abrasive particles or other media on the workpiece.

Q345B steel polishing method often used Polishing means a processing method by the action of mechanical, chemical or electrochemical, lower the q345b steel pipe surface roughness, to obtain a bright and smooth surface, and surface modification process making use of a flexible polishing tools and polishing abrasive particles or other media on the workpiece.

Polishing can not improve the dimensional accuracy or geometrical shape accuracy of q345b steel pipe, but can obtain a smooth surface or specular gloss, sometimes to be used to eliminate gloss. Usually buff as a polishing tool. Buff is generally made with multilayer canvas, leather crafted stacked, on both sides clamped with a metal circular plate, its rim coated abrasive mixture of powder and oil and other uniform.

(1) Mechanical q345b steel polishing surface corrosion resistance. As we know, the mechanical polishing q345b steel corrosion resistance is significantly lower than the electrochemical polishing q345b steel pipe, mainly due to the cold mechanical q345b polishing surface hardened steel deformed layer high corrosion rate, coupled with in the mechanical polishing process, inevitably have abrasive particles embedded in the deformable layer, the corrosion rate of deformation layer increased greatly.

(2) electrochemical q345b steel polishing makes the metal surface hardening layer easy to be dissolved, and can lower the surface activity, what’s more, there is a continuous passivation film formed on the surface, significantly improved the corrosion resistance.

Q345 Steel Properties and Introduction

Q345B steel is a Chinese standardized low alloy, medium tensile strength steel made with a hot-rolling process, and is used for a number of manufacturing purposes. It is a steel with less than 0.2 percent of its composition made up of carbon, less than 0.55 percent of its composition made of silicon and several impurities (mostly sulfur, chromium and nickel). This particular grade of steel is a 'general purpose' manufacturing steel in construction equipment field, such as Q345B is basic mateiral of making excavator bucket and long boom arms.

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.

Mechnical property for Q345B low alloy structural steel:
Tensile strength yield strength

1, Yield Strength

A yield strength or yield point is the material property defined as the stress at which a material begins to deform plastically. Prior to the yield point the material will deform elastically and will return to its original shape when the applied stress is removed, Yield strength of Q345B is 345 MegaPascals. Like most steels of its grade, it suffers elongation before it pulls apart, typically at 20-21 percent of its initial length.

2, Tensile strength

The tensile strength of a material is the maximum amount of tensile stress that it can take before failure, for example breaking. Steel tensile strength is expressed in units of force divided by cross sectional area; in the Metric system, this unit is known as the Pascal. One Pascal is a Newton (the force needed to accelerate a one kilogram object to a velocity of one meter per second) per square meter. The tensile strength of Q345B steel is rated at 470 to 660 MegaPascals (where mega is million).

Thickness (mm)
Q345B ≤ 16 > 16 ≤ 35 > 35 ≤ 50 >50
Yield strength (≥Mpa) 345 325 295 275
Tensile strength (Mpa) 470-630

Steel tensile strength is expressed in units of force divided by cross sectional area; in the Metric system, this unit is known as the Pascal. One Pascal is a Newton (the force needed to accelerate a one kilogram object to a velocity of one meter per second) per square meter. The tensile strength of Q345B steel is rated at 470 to 630 MegaPascals (where mega is million) and a yield strength (where the material starts to thin and pull like taffy) at 345 MegaPascals. Like most steels of its grade, it suffers elongation before it pulls apart, typically at 20-21 percent of its initial length.

Chemical composition for Q345B low alloy structural steel (Heat Analysis Max%)
Main chemical elements composition of Q345B
C Si Mn P S V Nb Ti
0.20 0.55 1.00-1.60 0.040 0.040 0.02-0.15 0.015-0.060 0.02-0.20

The equivalent steel grade with Q345B are EN 10025-2 S355JR,ASTM A572/A572 A572 Grade 50 and DIN 17100 St52-3.

Worldwide equivalents of grade Q345B:

The density of Q345B steel is approximately 7.8 (where water is 1.0), and it is commonly available in thicknesses ranging from 2 mm to 12.7 mm (12.7 mm is approximately half-inch thick plates), with sheets typically sold in 1 to 1.35 meter wide splits.

EU 
EN
USA
-
Germany
DIN,WNr
Japan
JIS
France
AFNOR
England
BS
Canada
HG
European old
EN
Italy
UNI
Belgium
NBN
Spain
UNE
China
GB
Sweden
SS
Inter
ISO
Portugal
NP
India
IS
S355JR (1.0045)
A572
A678Gr.A
SSGrade50
St52-3
SM490A
SS490
E36-2
50B
350W
350WT
Fe510B
Fe510B
AE355B
AE355B
Q345B
Q345C
2132-01
E355C
Fe510B
FE510-B
IS961

The major benefit of this grade of steel is its mild temper. It's easy to form and easy to weld.

Q345 Steel Properties and Introduction

Q345 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 Q345 Steel
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 (≥ 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)

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 by Q355 in the latest version of GB standard “GB/T 1591 – 2018”, the previous version is “GB/T 1591 – 2008”.

Tags: Q345A steelQ345B steelQ345C steelQ345D steelQ345E steel

Weled steel pipe specification, Standard and identification

Welded steel pipe (steel pipe manufactured with a weld) is a tubular product made out of flat plates, known as skelp, that are formed, bent and prepared for welding.

Figure1
Hot dip galvanizing

Galvanized pipe process characteristics

What is Galvanized Steel Pipe? Galvanized steel can be made into a strong plumbing or tubing material -- one that resists corrosion from exposure to water or the elements. It has been used used for water-supply pipes or as a strong tubing for outdoor applications.



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