TY - GEN A1 - Munikoti, Vijayendra K. A1 - Brekow, Gerhard A1 - Tessaro, Ute A1 - Erhard, Anton T1 - Ultrasonic inspection for transverse defects in dissimilar metal welds N2 - As a part ofthe cooling circuit in many nuclear power installations, dissimilar metals are welded together - for example, weid overlay cladding of austenitic material (either Inconel or 1.4550) on low alloy Steel. These welds are prone to stress corrosion Cracking. In some ofthe nuclear power stations, cracks were detected on the inner surface of the dissimilar weid. These cracks, which have their Orientation perpendicular to the weiding direction, are designated as transverse cracks. The purpose of the present investigation is to develop an ultrasonic testing method for reliable detection ofsuch transverse cracks. Very offen, crack detection and sizing in dissimilar welds with ultrasound can be very difficult due to the following reasons: 1. In a weiding process, high thermal gradients exist between the molten weid pool and the neighbouring colder regions. During the solidification process, grains grow along the direction of heat flow, yielding a textured structure. This results in a microstructure consisting of elongated grains, which causes the anisotropic nature of the weid region. An elastic wave in such an anisotropic medium undergoes beam skewing (i.e. phase and group velocity (Energy flow) directions are no longer coincident). 2. Due to the above mentioned grain structure, elastic properties vary spatially. This amounts to an ultrasonic wave undergoing multiple reflections at grain boundaries. The ray direction gets successively skewed at each grain boundary, resulting in a curved path. In addition to the grain boundaries, there are also interfaces between different parts ofthe dissimilar weid such as parent metal, transition layer, cladding and weid. At these interfaces, reflections and mode conversions occur in addition to scattering at grain boundaries. Altogether, ultrasonic inspection ofdissimilar welds for defect detection and sizing poses major challenges. Presently international research activities are concerned with the development of improved Signal Processing methods and optimizing strategies for qualifying ultrasonic inspection techniques for dissimilar welds. PY - 2012 SN - 978-3-87155-608-1 SN - 1618-4513 VL - 4 SP - 153 EP - 161 PB - DVS Media GmbH CY - Düsseldorf AN - OPUS4-26829 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Erhard, Anton T1 - Regulating the Use of New Materials in Containment Systems for Dangerous Goods T2 - MRS Fall Meeting CY - Boston, MA, USA DA - 2008-12-01 PY - 2008 AN - OPUS4-19637 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Erhard, Anton A1 - Goedecke, Thomas A1 - Menrad, Andreas A1 - Bethke, John T1 - Application of nondestructive testing - Methods for packaging examination N2 - Nondestructive testing (NDT) methods are applicable in many ways for defect detection as well as optimization of packaging production processes. The visual inspection method is the technique which is mostly used, although neither the customer nor a skilled inspector may be aware of this. Techniques like ultrasound for wall thickness measurement, the application of x-ray techniques or the use of dye penetrant techniques for crack detection are rather well known to the NDT family. However, acoustic emission techniques can also be helpful for the characterization of packaging materials. In this paper the employment of x-ray computer tomography (CT) for measurement of wall thickness in plastic jerrycans, especially on the edges, and its possible optimization of production processes will be discussed. A comparison of the CT and ultrasonic examinations of wall thickness and the reliability of this measured data are also important points for the discussion, especially if some safety factors can be derived from the results. The leakage test is also good for jerrycans, IBCs or other kinds of drums for the transportation and storage of dangerous goods. The disadvantage of this kind of test is that a lack of quality, e.g. wall thickness deterioration, cannot be detected if the wall thickness withstands the internal pressure. Therefore, especially for Quality assurance, the other, previously mentioned techniques are better for a statistical assessment of a batch. This paper is focused on the comparison of different NDT results with special emphasis on the large range of material mechanical properties. T2 - 25th IAPRI Symposium on Packaging CY - Berlin, Germany DA - 16.05.2011 KW - Materialeigenschaft KW - Zerstörungsfreie Prüfung KW - Computertomographie KW - Kunststoffbehälter PY - 2011 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-239191 SN - 978-3-940283-31-3 VL - 126 SP - 1 EP - 7 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) CY - Berlin AN - OPUS4-23919 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -