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70年代中期至80年代,在大量实践经验基础上形成了一套比较成熟的套装汽轮机叶轮键槽裂纹的超声波检测方法(简称作图法).该方法通过声程动态图、可疑信号与键槽圆角信号的起始点与消失点的位置判断裂纹信号及裂纹深度.该方法要求检验者具有丰富的实践经验,否则,很容易造成误判.最近,华北电力科学研究院提出了利用汽轮机叶轮形状尺寸精度比较高,而超声波测距比较准确的特点,以键槽圆角回波最高时的实测声程为已知条件,通过计算得出理论裂纹波幅最高时的声程值,以及理论裂纹波最高时与圆角波最高时两探头入射点之间的圆弧长度与实测值相比较,来判断裂纹及其高度的一种方法(简称计算法).本文根据实践结果对计算法提出了一些评价意见.1 试验情况
From the mid-1970s to the 1980s, based on a large amount of practical experience, a set of more mature ultrasonic testing methods for turbine wheel keyway cracks (referred to as the graphing method) were formed. The method was based on the sound path dynamic images, suspicious signals and keyway fillet Signal start point and vanishing point position to determine the crack signal and crack depth.This method requires the examiner has rich practical experience, otherwise, it is easy to cause misjudgment.Recently, North China Electric Power Research Institute proposed the use of turbine wheel shape and dimensional accuracy Is relatively high and the ultrasonic ranging is relatively accurate. The measured sound path when the keyhole fillet echo is the highest is known condition, and the sound path value when the theoretical crack amplitude is the highest is obtained, and when the theoretical crack wave is at the highest One of the methods to judge the crack and its height (the calculation method) is to compare the length of the circular arc between the two probe incident points and the measured value when the maximum angle of the circular wave is reached.This paper puts forward some comments on the calculation method according to the practical results. 1 test situation