UT Level 2 Course in Ultrasonic Testing, Practice-oriented

In a first video, the reflection amplitude is captured from several 3mm side drill holes at different depths and the results are evaluated so you can see the effect on the amplitude in the near and far field.  We also get an insight into the coupling tolerance that can occur in any inspection and what that means for the amplitude height and gain tolerance in dB.

Next, acoustic impedance is explained and some calculations are performed to determine the reflectivity of a sound beam at the steel/air and steel/water-based couplant interfaces. Here one can learn to what extent sound energy is reflected at interfaces and transferred to another medium.

The next topic is wavelength Lambda = speed of sound / frequency. Lambda is often used to describe or define the detectable defect size. This topic is discussed as this view of lambda is questionable.

Finally, some experiments are performed on a test block with a 1mm side hole. This artificial flaw is detected using a 2 and 4 MHz angle beam transducer to explain the influence of side reflections (geometry reflections) and beam overlap effects as well as mode conversion effects on the A-scan display. This helps to understand why other amplitudes are visible in addition to the flaw amplitude, which often cause confusion for UT operators in the field.

This session focuses on angle beam probes (= shear wave probes). The angle beam probes are also named according to their incidence angle in carbon steel (=mild steel). Therefore, first the design of these probes are explained in detail, especially with respect to their use for inclined beaming when such a probe is coupled to a carbon steel block. Refraction occurs at the interface between the delay line of the angle beam probe and the material steel. All the important factors related to the interior angle in the probe and effects in the steel object will be explained in detail and mathematically defined by the law of refraction (Snellius law) . It will also be explained how to find out if a standard angle beam probe is suitable to inspect materials other than steel and what happens in such cases with the different ultrasonic waves, longitudinal wave (= compression wave) and transversal wave (= shear wave).

The next topic is to explain the process of calculating the position of a reflector when detected using an angle beam probe, which is done automatically in the ultrasonic flaw detector nowadays. Here the trigonometric function is used to provide detailed information.

At the end a practical demonstration video will be shown which practically explains how the location of the reflector is determined and indicated in the flaw detector. This video also covers the procedure of calibrating the ultrasonic device using the V2 calibration block. At the end the results will be verified by manually measuring the position of the flaw relative to the probe. 

In this session you will learn about the most commonly used reference reflectors SDH (side drill hole) and FBH (flat bottom hole) used as comparison reflectors for natural flaws (=discontinuities). The advantages and disadvantages of both reference flaw and the related sizing method is explained in detail as part of the procedure how to apply these sizing methods DAC and DGS (AVG) using a flaw detector, calibration blocks and DGS diagram to find the size of the equivalent reference size of a natural discontinuity.

The preparation for a realistic inspection (flaw detection on a T-weld joint) is explained in detail including the definition of the reference level and calculating or estimating the capture of the SDH reference reflections from different distances.

Then the complete process of setting up the ultrasound system including the creation of the DAC curves is shown in a practical video.

Finally a video is shown with detailed information about the scanning (testing) procedure, determined results and discussion of the results.

Sound attenuation is explained and the usage of calibration blocks V1 and V2 in connection with range calibration and a practical video will show the differences between a manual and an automatic calibration on a V2 calibration block.

First, you will get an overview of the difficulties in sizing natural flaws. Then, the two main methods, DAC and DGS (AVG), will be introduced.

The advantages and disadvantages of both methods will be listed along with the limitations of using the DGS (AVG) diagrams that come with several standard probes.

Then, this session will focus on the powerful DGS (AVG) method for flaw sizing. Since it is a rather complex and difficult to understand method, you will learn step by step about the background and usage.

To get a good background understanding, some experiments will be presented where the size of two circular reflectors (flat bottom holes) of 2 mm and 5 mm diameter are determined in different ways using the ultrasonic device. First, the results provided by the instrument without using the special DGS (AVG) creation function will be used to determine the reflector sizes by reading from DGS (AVG) diagrams. One of these diagrams used came from the manufacturer Krautkrämer, the other was created in-house.

In the next step, the special function of the flaw detector "AVG (DGS)" was used to create the AVG curves directly in the flaw detector and to determine the 2 mm and 5 mm circular reflectors directly. Finally, a pre-saved file with ready-made AVG curves was used to find the reflector sizes.

All results were evaluated and compared with each other in order to also investigate the expected tolerance when using the different methods for flaw sizing.

This session first explains how to use the DGS (AVG) function, starting with the UT system calibration, the procedure for creating the DGS (AVG) curves based on a backwall reflection amplitude capture from the V2 calibration block and finally the verification of the correctness of the results.

The verification was performed using the special test block with 2mm and 5mm flat bottom holes at a 60 degree angle.

It is also aimed to get an idea of ​​the possible tolerance for the DGS (AVG) method of defect sizing.

Finally, all the results were discussed and evaluated, either read from the DGS diagrams or obtained using the DGS function in the instrument as well as using pre-installed DGS curves.

A practical demonstration video shows the whole procedure.

At the end, some important topics related to correction values ​​in dB are also explained. These correction values ​​depend on the probe design (size of the piezo element, frequency, angle) and calibration block used. Another correction value "transfer correction" relate to the possible differences in sound attenuation and surface roughness of the calibration block and the test object.