Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259128
Title: Ultrasonic inspection of austenitic stainless steel weldments
Author: Kapranos, Platon A.
Awarding Body: University of Aston in Birmingham
Current Institution: Aston University
Date of Award: 1982
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Abstract:
Ultrasonic waves interact in a complex manner with the metallurgical structure of austenitic weldments resulting in ambiguity when interpreting reflections and at times in misinterpretation of defect positions. In this work, current knowledge of the structure of austenitic welds is outlined, and the influence of this structure on the propagation of ultrasonic waves is reviewed. Using an established and highly accurate technique, data on velocity variations as a function of the angle between the direction of soundwave propagation and the axes of preferred grain orientation existing in such welds, are experimentally obtained. These results and existing theory are used to provide quantitative evidence of (i) anisotropy factors in austenitic welds, (ii) beam skewing effects for different wave modes and polarizations, and (iii) the extent of acoustic impedance mismatch between parent and weld metals. The existence of "false" indications is demonstrated, and suggestions are made into their nature. The effectiveness of conventional transverse wave techniques for inspecting artificial and real defects existing in austenitic weldments is experimentally investigated, the limitations are demonstrated, and possible solutions are proposed. The possibilities offered by the use of longitudinal angle probes for ultrasonic inspection of real and artificial defects existing in austenitic weldments are experimentally investigated, and parameters such as probe angle, frequency and scanning position are evaluated. Detailed work has been carried out on the interaction of ultrasound with fatigue and corrosion-fatigue cracks in the weld metal and the heat affected zones (HAZs) of 316 and 347 types of austenitic weldments, together with the influence of elastic compressive stresses, defect topography and defect geometry. Practical applications of all results are discussed, and more effective means of ultrasonic inspection of austenitic weldments are suggested.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.259128  DOI: Not available
Keywords: Engineering Materials ; Metallurgy Metallurgy
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