Braze welding of Dissimilar Materials

Abstract

Abstract:The article presents issues related to the braze welding process, discusses primary methods applied in industry as well as indicates characteristic features of the process, discusses the structure of joints most commonly used in industry and advanced braze welding methods enabling the obtainment of joints satisfying strict quality requirements. In addition, the article assesses the possibility of using the braze welding technology when repairing casts made of various casting alloys, discusses application areas for braze welded joints of materials characterised by different mechanical and physicochemical properties as well as presents metallographic and mechanical test results concerning braze welded joints made using a robotic CMT (Cold Metal Transfer) braze welding station.

Assessment of structure and selected mechanical properties of braze welded joints of copper-lined steel tubes

“…Selection of a filler metal for braze welding dissimilar materials is a big problem. Generally, its melting point corresponds to that of the lower-melting base material [10,11]. If the difference between melting points of the filler metal and the base material is small, it is not always possible to avoid partial melting of the edge of the lower-melting material [14].…”

“…An alternative for them can be low-energy versions of GMA (Gas Metal Arc) welding: ColdArc, STT (Surface Tension Transfer), CMT (Cold Metal Transfer), etc. [10], with synergic lines dedicated for the brazing process [11]. The low-energy arc joining processes are dedicated for materials sensitive to heat [12] and joining thin sheets [13].…”

“…The low-energy arc joining processes are dedicated for materials sensitive to heat [12] and joining thin sheets [13]. Application of braze welding significantly reduces the possibility of hot cracking, since, in this process, partial melting of the joined materials and mixing their components with the filler metal do not occur or are considerably reduced and the joint is obtained mainly by wetting and diffusion, like at brazing (less often at soft soldering) [10,11]. The way of preparing the materials for braze welding is identical to that applied in the welding process, i.e.…”

“…The way of preparing the materials for braze welding is identical to that applied in the welding process, i.e. with a gap or chamfered edges, with no capillary gap, characteristic for brazing [11].…”

Soldering of 7075 Aluminum Alloy Using Ni-P and Cu-Cr Electrodeposited Interlayers

“…During bonding the 7xxx series alloys, significant metallurgical difficulties appear [ 12 ]. In particular, traditional welding methods are limited (fusion welding), where the joint is obtained as a result of melting and mixing alloying components of the base materials and the filler metal [ 13 , 14 ]. Mixing the alloying elements often initiates creation of hard and brittle intermetallic phases that adversely affect mechanical properties of joints and, in the case of limited mutual solubility of the alloying elements, can also result in hot cracks in the joints and/or in the heat-affected zone (HAZ) [ 13 ].…”