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Since the 1947 inception of ductile iron, due to its various mechanical parts have wide adaptability and excellent process performance, and quickly developed into a very wide range of applications in mechanical engineering materials. Because of its superior corrosion resistance, strength and toughness, can withstand high water pressure, soil pressure and ground loads, the use of safe and reliable. Allows longer transmission distance, and can under adverse conditions laying of underground pipes, it is widely used in water, oil, gas pipelines in. Ductile iron pipe in the transport and underground laying, often withstand impact collisions, and then buried by soil pressure, in addition, to exclude sewage pipes, but also often by acid waste water corrosion. So ductile iron pipe is very necessary quality testing, in which the wall thickness and nodularity testing is particularly important. Uneven thickness or partial too thin can easily cause the carrying capacity of the local decline, it is prone to pipe bursts; ball rate directly affects the mechanical properties of ductile iron pipes, ductile iron is a measure of an important indicator of quality. Wall thickness tube at both ends can be measured with the measuring, but the middle part is difficult to be measured. Assessment of the current rate of the ball most of the sampling tube ends one interception, by optical experiments determine its rate of the ball, and use sampling test results represent the bulk of the tube ball rate, so it is not a true reflection of each part of the tube thickness and rate of the ball. Detection method not only can not guarantee the reliability of the entire length of pipe to use, and requires manual operation, a waste of time and materials. Our self-developed ultrasonic detection device online, the online real-time measurement of the thickness of each point of ductile iron pipe and ball rate. Reflection method used when measuring the thickness of thickness; nodularity using the transmission method determination is to measure the velocity of a point of ductile iron pipe, the speed of sound according to a linear relationship between the rate of the ball calculated nodularity of this point, the wall Thick and ball rate results intuitive, real-time display on the screen. From laboratory experiments and preliminary results of the actual test, the system capable of ductile iron pipe wall thickness and ball rate to achieve full-length, automatic, rapid measurement, stability and accuracy is good. As ductile iron pipe wall roughness is large and prone scum wall defects, rough surfaces affect the precision of thickness measurements. This paper summarizes the surface roughness of the pulse width and the peak position of the law and the possible impact of thickness measurement, not only for online testing of ductile iron has a very important significance, but also for all surface roughness material has guided ultrasonic thickness measurement of significance.
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