On-Line Measurement of Steel r-Valur with Ultrasonic Method

对生产线上钢板r值的在线测量进行了研究。非接触式技术依赖于超声波速度的测量，并将它们与r值相关联。这是可能的，因为速度的各向异性和塑性各向异性都产生的织构，在热轧，冷轧，最后退火的板材。不同的原理，洛伦兹力和磁致伸缩，为电磁声传感器（EMAT）进行了研究的基本对称兰姆波相速度的非接触，快速测量。最后的决定是磁致伸缩型，其中电磁铁施加平行于薄板平面的偏置场，并且曲折线线圈产生并检测感应的涡电流。该电磁超声换能器允许板最大厚度为2 mm时的抬离高达5 mm。其中三对被放置沿着三个主要方向的移动床单。使用平均通过时间和回归曲线计算平均r值。在Sumitomo Metal Indust.的连续退火线末端测试了包含这些EMAT的测量系统，导致对于最大400 m/min线速度的r值的0.1误差，而不管化学成分、厚度等的变化。每次输出的测量时间为20 msec。修正是必要的有关速度分散，起飞，和温度变化。结果表明，所研制的超声波探伤系统能够在真实的生产环境中保证钢板的质量。

Research has been made toward the on-line measurement of r-value for the steel sheets in the production line. The contactless technique relies on the measurement of ultrasonic velocities and relating them to the r-values. This is possible, because the anisotropy in velocities and the plastic anisotropy both arise from the texture which has developed during the hot rolling, the cold rolling, and finally annealing of the sheets.Different principles, Lorentz force and magnetstriction, for the electromagnetic acoustic transducers (EMATs) were investigated for the contactless, quick measurement of phase velocities of the fundamental symmetric Lamb wave. Final decision was the magnetostrictive type, for which the electromagnets applied the bias field parallel to the sheet plane and the meanderline coil generated and detected the eddy current induced. This EMAT allowed the liftoff up to 5 mm with the sheet maximum 2 mm thick. Three pairs of them were placed along the three principal directions of the moving sheets. Averaged r-values were calculated using the average transit times and the regression curve. The measurement system containing these EMATs were tested at the end of the continuous annealing line of Sumitomo Metal Indust., resulting in the 0.1 error of r-values for maximum 400 m/min line speed despite the variation of the chemical composition, the thickness, etc. The measuring time was 20 msec per output. Corrections were necessary concerning the velocity dispersion, the liftoff, and the temperature change. It is concluded that the ultrasonic system developed can contribute to the quality assurance of the steel sheets in the real production environment.