Journal of Engineering Studies and Research – Volume 18 (2012) No. 4 66 CONSIDERATIONS ON THE DEVELOPMENT OF BRAZED JOINTS USING TWO MATERIALS WITH DIFFERENT PROPERTIES OLARU IONEL 1* 1 “Vasile Alecsandri” University of Bacau, Calea Marasesti 157, Bacau, 600115, Romania Abstract: Realization of brazed joints involves the use of different joining materials. These joints are designed for various industries including the machine building and special industries such as aeronautics through the use of ceramics and metal brazing joints. Due to differences in material properties of brazing, the thermal expansion, different wetting and dispersion, residual stresses can occur in the joint. These residual stresses can be reduced through proper choice of brazing materials, fluxes and brazing temperature. Keywords: brazing, joint, base material, filler, wetting, dispersion 1. INTRODUCTION Process known as brazing is based on heating the base metal at higher temperatures than the solidus. Especially when brazed different materials are must be taken into consideration the possibility of forming intermetallic compounds due to the difference between thermal expansion coefficients. Numerous specialized studies have been conducted to examine how they can join two sheets with different materials. A special attention should be given to different mechanical properties of both base metals and filler metal protective atmosphere. If the materials are chosen wrong, in the material are high residual stresses can occurs even breaking of the brazed area [1-4]. The base materials should be chosen to be compatible with the brazing process, the filler materials and fluxes used to protect the brazed joints before and after brazing. To be fully charged, the filler metal liquid must be dispersed in the joint. In joining is formed a capillary zone in which the filler material must adhere to base materials due to the wetting and the dispersion [2, 3]. In scientific literature are presented the factors that influence behavior of the brazed materials (mechanical properties of the joint, corrosion resistance and residual stress levels) are: mode in which is realized heating of the brazing material, mechanical and chemical properties of base material, chemical composition of filler material, mode in which is realized cleaning of surfaces before brazing, fluxes and the protection atmosphere against the oxidation, Temperature and time of joint realization and aspect of brazed joint [3, 4]. In this paper we propose to determine the influence factors when using two materials with different mechanical and physical properties, thermal expansion coefficients are also different, some alternatives must be found so as not to appear premature rupture of the joint brazed. * Corresponding author, email: ionelo@ub.ro © 2012 Alma Mater Publishing House