Abstract��Abstract:Through analysis of E550?samples with ultrasonic flaw detected, it was found that the disqualification?was?caused by continuous casting?slag entrainment. But there was 200-300 ��m thick abnormal pure ferrite microstructure in the bond area of mould flux and?steel matrix.?The abnormal microstructure?around the defects was studied in detail with optical microscope and electron probe, etc. The results showed that, the disqualification was?caused by continuous casting?slag entrainment; the abnormal structure around mould flux was because of the presence of amorphous?powder SiO2; silicon-rich region was formed when silicon diffused?into steel during the solidification of liquid steel, so steel entered ��?phase region directly from liquid?state, forming?ferrite+a?small amount of pearlite structure only, rather than?tempered sorbite structure.
�����գ����Ǿ꣬��ƽ��. ����ƽ̨�ø�E550���쳣��֯��̽��[J]. �й������ڿ���, 2015, 33(2): 48-51.
LIU Dong-hui, ZHAO Ya-juan, LI Ping-he. Discussion on abnormal microstructure of offshore platform steel E550. Chinese Journal of Iron and Steel, 2015, 33(2): 48-51.
2015, Vol. 33 
