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6027 |
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Wednesday, May 22, 2019, Saal Brüssel 1:20 PM Diffusion brazing and bonding |
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Understanding solidification kinetics during TLP bonding of an austenitic stainless steel |
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Soufiane Guernaoui* / Institut Jean Lamour, France Bernard Rouat / Institut Jean Lamour, France Julien Zollinger / Institut Jean Lamour, France Hervé Combeau / Institut Jean Lamour, France |
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Understanding solidification kinetics during TLP bonding of an austenitic stainless steel Soufiane Guernaoui 1, Bernard Rouat1, Julien Zollinger 1, Hervé Combeau 1 1. Institut Jean Lamour - 2 allée André Guinier, Campus Artem, 54000, Nancy, France Transient liquid phase (TLP) bonding has been widely used in different industries to join or repair materials. In this study, the TLP bonding of an austenitic stainless steel using a Ni-Cr-Si filler alloy (FA) was investigated This work focuses on two mains objectives. First, the FA was characterized by differential scanning calorimetry and quenching during directional solidification experiment. Combining these two techniques made possible to determine the solidification path of the FA and to identify a temperature range with a liquid free of silicides for the process. Secondly, the effect of the thickness and holding time on the microstructural evolutions and the kinetics of isothermal solidification was investigated. 316L stainless steel was bonded at 1180°C using different thicknesses of FA. After holding times ranging from 0 to 24h, the samples were quenched to room temperature. The microstructure of the brazed joints is investigated by optical and scanning electron microscopy, energy dispersive spectrometer (EDS) and electron backscatter diffraction (EBSD). The experiments allowed to follow the evolution of the isothermal solidification length, the composition of the liquid and the phases formed in the remaining liquid as a function of thickness and time. Since the TLP bonding process is governed by silicium diffusion, the results allow to determine the critical brazing time from which no silicides can form anymore together with a quantitative evolution of the solidification kinetics. The results are compared and discussed with consistent models found in the literature. |