Abstract：According to the flaw detection nonconformity of 14 ~ 30 mm Q345C steel plate produced by 250*1650mm2 section continuous casting billet of Nanyang Hanye Special Steel Co., Ltd., by means of high power metallography, electron microscope and energy spectrum detection analysis, it is concluded that the flaw detection nonconformity is mainly caused by serious central manganese segregation and high manganese sulfide inclusion content. The flaw detection quality of steel plate can be improved by optimizing composition, reducing manganese content in steel, increasing secondary cooling strength of continuous casting, reducing sulfur content in molten steel, and slowly cooling steel plate during temperature snatching and offline. Through the adoption of measures, the qualified rate of flaw detection for rolled steel plates has increased from 98.40% to 99.80%.
Key words: steel plate; flaw detection; segregation; inclusion; qualified rate
2022, Vol. 29 