Cause Analysis and Study on Hole Defects of Cold-rolled Sheets

The causes and influencing factors of hole defects emerging in cold rolling process were analyzed by means of SEM and EDS.The result shows that the causes of holes defects include inclusions(the main cause),impressed foreign matters,and roll abnormity etc.The hole defects caused by inclusions are characterized by lacerated or dimpled fracture,or crescent-shaped appearance,and show little size difference on both sides of steel plates,their formation is mainly connected with steelmaking process.The hole defects caused by impressed foreign matters are characterized by noticeable mechanical scratches or indentations,and those defects with smooth fracture have different sizes in the two sides of plates,their formation is mainly connected with hot rolling and cold rolling processes.The hole defects caused by roll abnormity are characterized by equidistant regular holes,and their formation is mainly connected with roll abrasion and aging.According to characteristics of different types of hole defects,corresponding improvement measures have been put forward.