Steel pipe knowledge:Q345D steel pipe_ç™¾åº¦æ–‡åº“

Q345D A steel pipe material. Q stands for the yield of this material. The 345 behind it refers to the yield value of this material, which is around 345. And as the thickness of the material increases its yield value decreases.
Q345D steel pipe is one of the materials of straight seam steel pipe.
Q345A, Q345B, Q345C, Q345D, Q345E This is the distinction of the quality grade, which increases from A to E in turn, mainly due to the difference in the impact temperature caused by the difference in the content of microelements such as phosphorus and sulfur, and represents the difference in the impact temperature. The tube chemical composition mechanical properties.
Q345A class is not to make impact; Q345B class is 20 degree normal temperature impact; Q345C class is 0 degree impact; Q345D class is -20 degree impact; Q345E class is -40 degree impact. At different impact temperatures, the impact value is also different.
The Q-yield strength is not lower than 345Mp. The quality grade indicates the amount of impurity elements (carbon, manganese, silicon, sulfur, and phosphorus, which are impurity elements in the steel). The impurity content of A, B, C, and D will be greater. Less
Q345A contains less than or equal to 0.045% phosphorus and sulfur
Q345B contains less than or equal to 0.040% phosphorus and sulfur
Q345C contains less than or equal to 0.035% phosphorus and sulfur
Q345D contains less than or equal to 0.030% phosphorus and sulfur
Q345E contains less than or equal to 0.025% phosphorus and sulfur
The more phosphorus and sulfur impurities in the steel, the worse the impact toughness
Q345A -
Q345B aKV not less than 34 at 20 degrees Celsius
Q345C aKV at 0 degrees Celsius is not less than 34
AQV not less than 34 at Q345D -20 degrees Celsius
Q345E -40 degrees Celsius aKV not less than 27
The ultimate reason is that the reduction of the P and S impurity elements in the steel promotes the improvement of impact toughness at low temperature. One is the Q345 chemical composition and the other is the mechanical properties of Q345.
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