Scholarly record

CONTRIBUTIONS OF THE ULTRASOUND FIELD INFLUENCE ON CHEMICAL COMPOSITION CHANGE IN THE REWORKING PROCESS BY ULTRASONIC WELDING

Prof. Dr. Gheorghe Amza, Prof. Dr. Valentin Dan Petrescu, Assoc.Prof. Dan Florin Nitoi, Prof.Dr. Agustin Semenescu, Assoc.Prof. Oana Roxana Chivu

Abstract

The paper presents experimental results obtained in determining the chemical composition of the base material- heat affected zone пїЅ filler material in reworking by ultrasonic welding field. The work shows the curve of the concentration of carbon, nickel, chromium, molybdenum, iron, tungsten, silicon and cobalt in the resulted material couple. There are presented differences between reworking in ultrasonic field and common welding process. The analysis of the results obtained and presented in the paper shows the following: - an increase of 5 to 15% of the content of Cr, Mo, W, Fe, Si and Co in the heat-affected area and in the base material, in the vicinity of the heat-affected area, in case of welding in the field ultrasonic, due to the acceleration of the ultrasonic waves diffusion process; - a decrease of 5 to 10% of the Ni and C content in the thermally influenced area and in the base material and in the immediate vicinity of the heat-affected area in the case of ultrasonic welding due to the inhibition of the diffusion process from the material Base to ultrasonic waves; - the other components have an insignificant variation of the concentration on the deposited layer section and in the base material, except for the heat-affected area, where in the case of ultrasonic welding the content increases by 2 ... 5%, also due to the acceleration of the process The diffusion from the feed material to the base material; -somewhat similar behavior has also been achieved in the case of welding in the protective gas environment, the WIG process with and without ultrasonic activation of the reconditioned part.Due to the thermal cycle through which the feed material and the base material (heating-melting-cooling-solidification) and due to the dilution phenomenon accompanying the process occur, chemical composition changes occur in the three distinct areas: the addition material, the thermal influence zone and base material. Also, structural and proper changes occur, changes of the functional and technological characteristics of the three zones forming the torque resulting from the refurbishment by ultrasonic welding. Measurement of the chemical composition as well as of the functional characteristics was made from the outer surface of the deposited layer towards the inside of the base material with a pitch of 0.5. Samples were appropriately sampled and subjected to X-ray fluorescence chemistry according to STAS 11464-1980 or ISO 9556/2002.

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DOI resolver: doi.org/10.5593/sgem2017/41/s18.009

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