Root cause analysis of tiny spot defects on zinc coated steel sheets using EBSD
Three types of tiny spot defects on zinc coated automotive steel sheets,which were caused by longitudinal scratches,transverse scratches,and dents on substrate,respectively,were characterized using electron backscattered diffraction(EBSD)technology.The crystal structure characteristics of the corresponding defects on the substrate,including grain size,low and high angle grain boundaries,sub-grain,and strain distribution,help to determine the process unit where the defects occurred.In addition to normal recrystallized grains,low angle grain boundary sub-grains located inside recrystallized grains,and residual stress were observed on the cross sections of the three defects,indicating that only high-temperature recovery occurred after the defects on the substrate formed.Therefore,it is determined that these three defects all occurred from the end of soaking to slow-cooling unit in the continuous annealing line.
NETL
NSTL
万方数据
