The ultrasonic testing of the spot welded different steel sheets

• Autorzy: Vural M. , Akkuş A.
• Języki publikacji: EN

Abstrakty

EN

Purpose: Purpose of this paper is to investigate the applicability of spot welded different steel sheets to ultrasonic testing, because resistance spot welding of the steel sheets is widely used in the car bodies and transport fields and ultrasonic testing is a good way to evaluate the fatique life of the spot welds. Design/methodology/approach: Methodology of this paper is that two different steel sheets (AISI 304 type austenitic stainless steel sheet and Galvanized steel sheet ) were welded to each other by using resistance spot welding. Some pre-welding tests were made to obtain suitable and optimum weld nugget diameter; and the welding current vs. nugget diameter curve were obtained. By using this curve and kepting constant welding parameters such as current, electrode pressure, weld time, etch., fully identical four spot welded specimens having 5 mm (±0.2) nugget diameter were obtained. The specimens and nugget diameters were tested by using a special ultrasonic test apparatus which is designed for spot welded joints. Findings: Findings are that after the first ultrasonic tests, the four identical spot welded sheets which have AISI 304 - Galvanized steel sheet combination were subjected to the fatigue test in four different number of cycles. There is no any rupture or fracture in spot welded joints after fatigue tests. The spot welded specimens subjected to fatigue test were tested in ultrasonic test apparatus to observe the variation in the weld nugget and joint. The ultrasonic test results before fatigue and after fatigue were compared with each other; and the decreasing of the weld nugget diameter were observed while increasing the number of cycles. The results were shown in figures and discussed. Research limitations/implications: Spot welding of different steel sheets forms different microstructures which respond different values to ultrasonic testing. Evaluation of these responses are quiet difficult. Practical implications: Only a few spot welds can be evaluated among approximately 4 thousands of spot welds on a car body. Only selected spot welds can be ultrasonically tested. Originality/value: Resistance spot welding of AISI 304 and galvanized steel forms austenitic, martensitic and ferritic microstrucutre in the same weld region. Ultrasonic testing of austenitic microstructures is different than the other microstructures. In this study the response of different microstructures to ultrasonic waves are investigated.

Słowa kluczowe

EN

ultrasonic testing non-destructive; resistance spot welding; different austenitic steels

PL

badania ultradźwiękowe; badania nieniszczące; zgrzewanie rezystancyjne punktowe; stale austenityczne

• Wydawca: International OCSCO World Press
• Czasopismo: Journal of Achievements in Materials and Manufacturing Engineering
• Rocznik: 2006
• Tom: Vol. 18, nr 1-2
• Strony: 247--250
• Opis fizyczny: Bibliogr. 9 poz., rys., wykr.

Twórcy

autor

Vural M.

• Mechanical Engineering Faculty, Istanbul Technical University, 34437, Istanbul, Turkey

autor

Akkuş A.

• Mechanical Engineering Faculty, Istanbul Technical University, 34437, Istanbul, Turkey

Bibliografia

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