S355JR – → Q345B
S355J0 – → Q345C
S355J2 – → Q345D
S355K2 – → Q345E
S355MC – → QStE340TM or QStE380TM or Wusteel : WL510
S355J2G3W – → Q345GNHL
S355NL is a normalized steel (fine-grained steel) in the EN10025-3:2004 standard. Its yield strength and tensile strength correspond to my country’s Q345 low alloy steel. NL is required to absorb impact in a low temperature environment of minus 50 degrees. Work test·and the impact value is not less than 27J.
S355 is a European standard low alloy high strength plate
The steel grade must consist of the following parts:
—This standard number (EN10025-2);
—Steel name or steel number: The steel name consists of the following parts:
—Symbol letter S (structural steel) or E (engineering steel);
—Description of the minimum yield strength in MPa for thicknesses ≤16 mm;
—When feasible, mark the name of the mass component of the impact energy;
— where feasible, mark letters for special purposes;
– If the product is delivered in “+N or +AR” status, it must be marked “+N or +AR”.
quality level
EN10025-2 quality grades are divided into S355JR, S355J0, S355J2, S355K2,
EN10025-23 quality grades are divided into S355N S355NL.
chemical composition
Take S355J2 as an example:
Deoxidation method: FF; C: ≤ 0.22; Si: ≤ 0.55; Mn: ≤ 1.60; P: ≤ 0.025; S: ≤ 0.025; Cu: ≤ 0.55;
Z25 refers to the thickness direction lamellar tear resistance test of steel plates, which mainly considers the seismic requirements.
What are the differences between S355 and Q345B, and what are the differences in welding?
S355 is slightly stronger than Q345B, but the welding is exactly the same.
The main purpose:
S355 has been widely used in the manufacturing of engineering machinery, ships, bridges, high-rise buildings, boilers and pressure vessels, electric power, and various vehicles.
Process performance:
Including metal’s weldability, cutting performance, cold and hot processing properties, heat treatment properties, forgeability, uniform structure stability and large cross-section hardenability, etc. When considering the cost of materials, the impact of different eases of material processing and welding on manufacturing costs should also be considered.
Q345 (Q355)
Q345 is a kind of steel. It is a kind of low alloy steel that is widely used in bridges, vehicles, ships, buildings, pressure vessels, special equipment, etc., where “Q” means yield strength, and 345 means that the yield strength of this steel is 345MPa.
The yield value of Q345 will decrease as the thickness of the material increases, and the domestic one may be less than 345MPa, so the strength must be less than 345MPa during mechanical design, otherwise there will be problems.
Reference standard: GB/T1591-2018 “Low alloy high-strength structural steel”
Note: Compared with the old standard, the latest Q345 standard GB/T1591-2018, the most obvious change is the change in Mn element content, which has been corrected from the original 1.0-1.60 to ≤1.70, and the minimum value limit has been cancelled.
With the development of modern industry and the continuous advancement of science and technology, various trace elements are more widely used in steel plates. Mn content is no longer the only factor affecting the strength and mechanical properties of steel. Therefore, the low-alloy high-strength structural steel standard jointly issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China and the China National Standardization Administration cancels the limit on the Mn content range and only stipulates the maximum value.
For the testing of Q345 steel, on the one hand, it is whether the element content of the steel meets the national standard requirements. On the other hand, the most important thing is to detect whether the mechanical properties (yield strength, tensile test) of the steel meet the standards through professional institutions.
chemical composition:
Q345A:C≤0.20,Mn≤1.70,Si≤0.50,P≤0.035,S≤0.035;
Q345B:C≤0.20,Mn≤1.70,Si≤0.50,P≤0.035,S≤0.035;
Q345C:C≤0.20,Mn≤1.70,Si≤0.50,P≤0.030,S≤0.030,Al≥0.015;
Q345D:C≤0.18,Mn≤1.70,Si≤0.50,P≤0.030,S≤0.025,Al≥0.015;
Q345E:C≤0.18,Mn≤1.70,Si≤0.50,P≤0.025,S≤0.020,Al≥0.015;
Q345A, B, C, D and E all contain Nb≤0.07, V≤0.15, Ti≤0.20, Cr≤0.30, Ni≤0.012, Mo≤0.10
Q345A, Q345B, Q345C, Q345D, Q345E. This is a distinction between levels, and what it represents is mainly that the temperature of the impact is different!
Q345A level, no impact; Q345B level, 20 degree normal temperature impact; Q345C level, 0 degree impact; Q345D level, -20 degree impact; Q345E level, -40 degree impact. At different impact temperatures, the impact values are also different. Among the plates, it belongs to the low alloy series. Among low alloy materials, this material is the most common. One of the past names of Q345 was: 16Mn.
The external implementation standard of Q345 is: GB709, and the internal implementation standard is: GB/T1591-2008
Due to implementation of standards, this type of steel plate is allowed to be delivered with negative tolerances.
Mechanical properties
Q345D seamless pipe mechanical properties:
Tensile strength: 490-675MPa Yield strength: ≥345MPa Elongation: ≥22%
Q345B seamless pipe mechanical properties:
Tensile strength: 490-675MPa Yield strength: ≥345MPa Elongation: ≥21%
Q345A seamless pipe mechanical properties:
Tensile strength: 490-675MPa Yield strength: ≥345MPa Elongation: ≥21%
Q345C seamless pipe mechanical properties:
Tensile strength: 490-675MPa Yield strength: ≥345MPa Elongation: ≥22%
Q345E seamless pipe mechanical properties:
Tensile strength: 490-675MPa Yield strength: ≥345MPa Elongation: ≥22%
S355J2G3 adopts the European standard EN10025-2, compiled by the ECISS/TC10 “Structural Steel Grade and Quality” Technical Committee. This European standard is implemented in CEN member countries, including Austria, Belgium, Sepulus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, and Malta , Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
——The symbol letter S represents structural steel;
——Description of the minimum strength in MPa for thickness ≦16mm;
——When feasible, mark the name of the quality group of impact energy;
— where feasible, mark the letter C for special purpose letters;
——Belongs to alloy structural steel;
s355j2g3: Low alloy high-strength structural steel Q345 S355J2G3 is roughly equivalent to GB’s Q345D S355J2G3. J2G3 means that the delivery state is normalizing, the impact power at -20°C is 27J, and G3 and G4 mean the deoxidation method.
The composition is C ≤ 0.20, Si ≤ 0.55, Mn ≤ 1.60, P ≤ 0.035, S ≤ 0.035. Deoxygenation method FF.
S355j2g3: Low alloy high strength structural steel Q345 S355J2G3 is roughly equivalent to GB’s Q345D S355J2G3. J2G3 indicates the delivery status is standardized and the impact energy at -20°C is 27J. G3 and G4 mean deoxygenation.
Q345A level, no impact; Q345B level, 20 degree normal temperature impact; Q345C level, 0 degree impact; Q345D level, -20 degree impact; Q345E level, -40 degree impact. At different impact temperatures, the impact values are also different. Among the plates, it belongs to the low alloy series. Among low alloy materials, this material is the most common. One of the past names of Q345 was: 16Mn.
S355J2G3 adopts the European standard EN10025-2, compiled by the ECISS/TC10 “Structural Steel Grade and Quality” Technical Committee.
s355j2g3: Low alloy high-strength structural steel Q345 S355J2G3 is roughly equivalent to GB’s Q345D S355J2G3. J2G3 means that the delivery state is normalizing, the impact power at -20°C is 27J, and G3 and G4 mean the deoxidation method.
The symbol letter S represents structural steel; a description of the minimum strength in MPa when the thickness is ≦16mm; when feasible, the letter C is marked for special purposes; it belongs to alloy structural steel;
Hua Steel Co., can customize S355 series, Q355 series, E355 series, seamless steel pipes and precision steel pipes made of domestic and foreign standard materials according to customer requirements.
