Reason Analysis on Defects of Low Alloy Steel Medium Plate by Ultrasonic Detection
LAI Chao��bin1,2,XIN Bo1,CHEN Wei��qing1,L�| Rui��guo2,WU Shao��jie1,2
1.School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China��2.Technique Centre of Xinyu Iron & Steel Co Ltd, Xinyu 336501,Jiangxi, China
Abstract��By analyzing the low qualified percent of low alloy steel medium plate by ultrasonic detection, the research on macrostructure, microstructure, SEM and fracture are carried out. The results showed that the defects in steel plate were mainly caused by higher content of [H] and serious centerline segregation in plate. Aggregation of hydrogen near the stripy MnS inclusion led to the hydrogen induced crack��and the martensite and bainite produced due to the central segregation in plate led to the increase of the stress concentration which induced the crack under the condition of rapid cooling after rolling. It was learned from the calculation that the hydrogen concentration in the hydrogen trap at the front of stripy MnS inclusion was higher than the maximum saturated concentration in the hydrogen trap, so that cracks were created. The percent qualified by ultrasonic test were greatly increased by slow cooling both of slab and medium plate after rolling.
������;����;��ΰ��;�����;���ܽ�;. �ͺϽ��к��̽��ȱ��ԭ����[J]. �й������ڿ���, 2008, 26(1): 44-0.
LAI Chao��bin;XIN Bo;CHEN Wei��qing;L�| Rui��guo;WU Shao��jie;. Reason Analysis on Defects of Low Alloy Steel Medium Plate by Ultrasonic Detection. Chinese Journal of Iron and Steel, 2008, 26(1): 44-0.
2008, Vol. 26 
