Total focusing method(TFM)imaging technology is a kind of virtual focus image post-processing technology based on full matrix collection,and this algorithm split image area into multiple grids,then focus on each grid.The result of ultrasonic imaging is smoother,and image quality is better than that of conventional phased array detection method.It is easy for inspectors to judge the defects of the detection images.According to the technical characteristics of TFM,this paper studied the technology scheme of ultrasonic phased array TFM detection.TFM verification test blocks were designed and manufactured according to the design standards for girth weld test blocks of pipelines.Phased-array ultrasonic TFM testing tests were carried out with TFM calibration test blocks and AUT calibration test blocks.Experimental results showed that,For V-type groove,the TFM imaging effect was good.For automatic welding grooves with small angles,conventional full focus detection was difficult to receive ultrasonic echoes and had low detection sensitivity.By optimization and improvement of the full focus algorithm,the detection rate of small angle defects was improved,it was proved that the TFM technology can be used for the fully automatic welding process,this study provided a technical basis for the application of TFM technology in the girth weld field of pipeline.
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