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Spajanie poprzez topienie kontaktowe w układzie Ag-Cu

100%

Araee A. , Senkara J.

tom R. 79, nr 9

109-112

Badano proces topienia kontaktowego w modelowym układzie Ag-Cu. Ustalono, iż ilość powstającej fazy ciekłej jest kontrolowana poprzez czas kontaktu oraz - w decydujący sposób - przez temperaturę. Sformutowano założenia do termodynamicznego modelu procesu. Na postawie analizy struktury otrzymanych złączy zaproponowano mechanizm powstawania złączy, składający się z pięciu etapów. Wyniki znajdą zastosowanie w opracowywanej metodzie lutowania z zanikająca fazą ciekłą w bardziej złożonym układzie.

Contact melting in the model Ag-Cu system was investigated. It was revealed that an amount of produced liquid is controlled by the time of contact and mostly by temperature. Assumptions for thermodynamical model were formulated. Principles of the joint formation were proposed basing on structutal analysis. The results of the work will be implemented in transient liquid bonding in much more complicated system.

Experimental and numerical analysis of shunting effect in resistance spot welding of Al2219 sheets

70%

Vardanjani M. J. , Araee A. , Senkara J. , Jakubowski J. , Godek J.

2016

tom Vol. 64, nr 2

425--434

Few aspects of shunting effect have been studied so far. Shunting effect in resistance spot welding (RSW) occurs when the electrical current passes through the previous spot welds. Value of this current depends mostly on distance, number, and size of previous spot welds. This will cause some dimensional and metallurgical changes in welding nugget as well as heat affected zone (HAZ). In this study, shunting effect of RSW is considered by finite element method (FEM) and the results are compared to experiments performed on aluminum alloy 2219. Weld spacing together with welding current and time are considered to discover the effect of shunting current in the final quality of nugget. A three factor experiment design has been performed to find the significance of factors and interactive effects, as well as finite element model verification. Electrothermal and mechanical interactions are considered in the FEM. Experimental and numerical solutions have yielded similar results in terms of welding nugget properties. Asymmetry in electrical potential, temperature, stress distribution and geometry of shunted nugget is predicted and verified directly or indirectly. Intense effect of shunting current on nugget height, asymmetric growth of heat affected zone (HAZ) toward previous welding nugget, as well as concentration of alloying elements along grain boundaries are also discovered.