Cause analysis and improvement measures of flaw detection for Quenched and tempered Q345R steel plat

During the production of quenched and tempered Q345R steel plate, a large number of unqualified flaw detection occurred. The unqualified flaw detection area was sampled and the microstructure of the unqualified flaw detection quenched and tempered Q345R steel plate was observed and analyzed by means of metallographic examination and scanning electron microscopy. It was found that the defects such as inclusions and central cracks caused the flaw detection. The analysis shows that the original crack of billet causes the crack after rolling in the quenched and tempered Q345R steel plate, and the calcium aluminate inclusion in the molten steel refining process does not float sufficiently, resulting in the inclusion of large size in the quenched and tempered Q345R steel plate.

Improvement measures for the purity of molten steel and internal quality of billet are put forward. The qualified rate of improved quenched and tempered Q345R steel plate flaw detection has increased by 12%, and the effect is better.

Because of the harsh application environment of quenched and tempered Q345R steel plate, Q345R steel plate is necessary to have a great tolerance to temperature, pressure and so on. In the production process of quenched and tempered Q345R steel plate, the requirements for the structure and performance of the steel plate are very high, and the requirements for flaw detection are very strict.