• Sale03-QD steel building

1.The difference in the implementation of standards

Q345B grade representation method: The grade of steel is composed of three parts: Chinese Pinyin letters representing yield strength, yield strength value and quality grade symbol.

For example: Q345B, where:

Q---the first letter of the word "qu" in Chinese pinyin for the yield strength of steel;

345---The strength of each session. Unit Mpa;

B--- The quality grade is B.

When the demand side requires the steel plate to have thickness direction performance, the symbol representing the thickness direction (Z direction) performance level is added to the above specified grade, such as: Q345BZ15.

Q345B implementation standard: GB/T1591-2008 "Low alloy high strength structural steel".

The steel grade consists of four parts: the first letter Q in Chinese pinyin representing the yield strength "Qu", the specified minimum upper yield strength value, the delivery status code and the quality grade symbol.

For example :Q355NB. Among them:

Q---the first letter of the word "qu" in Chinese pinyin for the yield strength of steel;

355---the specified minimum upper yield strength, expressed in MPa;

N---Delivery condition is normalizing or normalizing rolling:

B--- The quality grade is B.

Q355B implementation standard: GB/T1591-2018 "Low alloy high strength structural steel".

2.The difference of mechanical properties

Mechanical properties of Q345B / Q355B

Yield strength:

≤16mm: ≥345; ≤16mm: ≥345;

16-40mm: ≥335;16-40mm: ≥345;

40-63mm: ≥325;40-63mm: ≥335;

63-80mm: ≥315; 63-80mm: ≥325;

80-100mm: ≥305;80-100mm: ≥315;

100-150mm: ≥285;100-150mm: ≥295;

150-200mm: ≥275; 150-200mm: ≥285;

200-250mm: ≥275; 200-250mm: ≥275;

250-400mm: ≥265;no.

Tensile strength: 450-630Mpa.

Elongation: ≥21%.

Impact test: 20℃

3.Delivery status

Q345B and Q355B steel plate to control tie, normalizing, normalizing + tempering, hot mechanical rolling (TMCP) and other states of delivery, if necessary according to customer needs also need to do 2-way performance test, such as Q345D-Z15, Q345D-225, Q345D-Z35 and so on. The inspection grade has national standard one probe, second probe, third probe.