Forum Technical Discussions      Re: flaw checking Posted by: S.V.Swamy (PID_839), E-mail: Address, on December 09, 2008 at 17:36 : In Reply to: flaw checking posted by : LANRE ALAPINI , E-mail: Address, on December 09, 2008 at 16:27 : ----------- Start Original Message ----------- : can any body explain the term lack of back wall reflection ------------ End Original Message ------------ Lack of back wall reflection or echo means that the transducer is not receiving the ultrasound signal reflected from the back surface (opposite side of the test object). This can happen due to one or more of the following reasons: It is assumed that the instrument and the probe are working and that the range has been calibrated properly. Very rough surface resulting in poor coupling Highly curved surface resulting in sound not entering the test object Lack of parallelism between the test surface and the back surface, for example a wedge Sintered material with lot of porosity. We had some interesting experiences while testing hot rolled austenitic stainless steel plates and tungsten-copper blocks. If any one is interested, I will share. Or I may submit a short case study like paper. Swamy NDT Guru Follow Ups: Post a Followup: Name: E-Mail: Subject: Comments: ----------- Start Original Message ----------- : : can any body explain the term lack of back wall reflection : Lack of back wall reflection or echo means that the transducer is not receiving the ultrasound signal reflected from the back surface (opposite side of the test object). This can happen due to one or more of the following reasons: : It is assumed that the instrument and the probe are working and that the range has been calibrated properly. : Very rough surface resulting in poor coupling : Highly curved surface resulting in sound not entering the test object : Lack of parallelism between the test surface and the back surface, for example a wedge : Sintered material with lot of porosity. : We had some interesting experiences while testing hot rolled austenitic stainless steel plates and tungsten-copper blocks. If any one is interested, I will share. Or I may submit a short case study like paper. : Swamy : NDT Guru ------------ End Original Message ------------ Optional Link URL: Example: "http://www....html". Alternative write "http://www.ndt.net/wshop/attach/filename.htm" if you transfered a filename.htm via FTP Page Title: is important! Optional Image URL: http://www....gif Attention! Please click the button only once. This may take a moment to process Forum Technical Discussions Help