Cause analysis of surface blackening of SPHC hot rolled strip after pickling
ZHOU Cong-rui 1， CHEN Xiao-long 1， ZHOU Ming-ke 1， FAN Lei 1，MEI Peng 2，BAO Si-qian 2
1. Technology Center， Liuzhou Iron and Steel Co.， Ltd.， Liuzhou 545000， China； 2. Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education， Wuhan University of Science and Technology，
Wuhan 430081， China
Abstract：The oxide scale of SPHC hot rolled strip produced by Liuzhou Iron and Steel Co.， Ltd. was difficult to be removed by pickling. Moreover， the surface of the plate appeared blackening in varying degrees after pickling， which affected the surface quality of pickling strip. The causes of blackening phenomenon of strip after pickling were explored by several testing and analysis methods， including roughness tester， X-ray diffractometer， scanning electron microscope and static pickling test. The results showed that the contents of residual Cu， Ni， Cr and As in SPHC strip produced by Liuzhou Iron and Steel Co.， Ltd. were high. These residual elements would be enriched in the matrix metal under the oxide scale， which enhanced the adhesion force of oxide scale， resulting in the difficulty of pickling. The residual oxide scale caused the surface blackening of strip after pickling. By controlling the content of residual elements， the surface color and luster of strip after pickling was obviously improved.
2020, Vol. 38 
