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，并将其与r值联系起来。这是可能的，因为速度的各向异性和塑性各向异性都是由薄板在热轧、冷轧和最后退火过程中形成的织构引起的。研究了基于洛伦兹力和磁致伸缩原理的电磁声换能器（EMATs）非接触、快速测量基本对称兰姆波相速度的方法。最后确定为磁致伸缩型，即电磁铁施加平行于薄片平面的偏置场，并在弯曲线线圈上产生感应涡流。该EMAT允许上升至5毫米，最大厚度为2毫米。沿着移动板的三个主要方向放置了三对。利用平均穿越时间和回归曲线计算平均r值。在住友金属工业连续退火生产线的末端对包含这些emat的测量系统进行了测试。，导致最大400 m/min线速时，尽管化学成分、厚度等发生变化，r值误差为0.1。测量时间为每输出20毫秒。对速度分散、升空和温度变化进行修正是必要的。研究结果表明，所研制的超声波检测系统能够有效地保证钢板在实际生产环境中的质量。

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.