Removal Behavior of Inclusion During RH Vacuum Treatment of X70 Pipeline Steel
YANG Guang-wei1，CHU Ren-sheng1，WANG Xin-hua1，HUANG Fu-xiang1，WANG Wan-jun1，YIN Yu-qun2
1. School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China 2. Nanjing Iron and Steel Co., Ltd., Nanjing 210035, Jiangsu， China
Abstract：Inclusion morphology, composition, number and size at various times of the RH vacuum treatment were investigated on X70 pipeline steel with ASPEX. Results suggest that: The inclusions are mainly liquid globular CaO-Al2O3 with a small amount of MgO throughout RH vacuum treatment. Inclusion number decreases with time and decreases by 70% after 28min RH vacuum treatment. Inclusion number after RH treatment can be dramatically reduced by reducing inclusions before RH treatment. The total inclusions and inclusions with size 1-5μm is monotonously decreased in number, while inclusions over 5μm firstly increase then decrease after reaching the maximum. It takes more time for bigger inclusions to reach the maximum. The average diameter of inclusions increases from 2.2-2.5μm before RH to 3.0-3.9μm after RH.
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2014, Vol. 49 
