Papers by Keyword: Weldability Window

Abstract: This paper explains the technique of explosive welding for joining SS304 and Al 6061 using Copper interlayer. The joining was done in two stages. In the first stage SS304 (thickness: 20 mm) was joined to Copper (thickness: 3mm). Second stage involved joining of SS-Cu plate to Al 6061 (thickness: 8 mm).The paper presents detailed discussion on important parameters required for explosive welded process. The most important parameter is minimum and maximum flyer plate velocity required for creating the impact. Collision angle and angle of impact are also discussed. Another important parameter is the Velocity of detonation (VOD) of explosive to be used. The explosives used have VOD of the order of 2500 m/s and 1600 m/sec. Since the explosive welding process involves formation of jet between two surface, therefore surface conditions of the base and flyer plate like its flatness, roughness and cleanliness which are very critical for proper joining have been discussed in this paper. Chisel test (which is considered to be most rugged test) was conducted on the joint. The test confirmed successful joining.The paper explains how use of trimonite expands the weldability window in comparison to NGU when used for direct SS to Al alloy welding.It also compares the results obtained by use of two different powder explosives to obtain the same tri-layered plate via two different routes. The results are particularly interesting because both the explosives have substantial difference in their properties such as Velocity of Detonation, Gurney Characteristic Velocity, density and homogeneity which can be used as advantages from different angles of views.

Abstract: In explosive cladding, the kinetic energy spent at the dissimilar interface transformed into thermal energy and characterizes the quality of clad. Explosive cladding with interlayer enhances the kinetic energy utilization and restricts the intermetallic formation. The introduction of interlayer increases the heat transfer area and duration of collision and, consequently, the time available for thermal energy transferred into the metals. The thermal energy is transferred to the participant metals by conduction and convection. The influence of interlayer between flyer and base plates on weldability window, an analytical estimation is also reported.

Abstract: Explosive cladding produces a strong weld between two dissimilar metals using explosive energy. The influence of material properties in achieving strong AluminiumSteel, CopperSteel explosive clad is discussed in this study. The solidification microstructure is determined by the nature of the competitive growth between adjacent columnar grains and, therefore, has a significant influence in the final characteristics of fusion zone. A compatible interlayer can significantly reduce the solidification time resulting in an intermetallics free interface. The influence of interlayer in the lower limit of weldability window is also discussed.

Abstract: Explosive welding of two dissimilar metallic sheets is accomplished by the exhaustive deformation owing to high pressure and high temperature created at the collision place. This study addresses the analytical estimation of the dissipation of potential energy of the explosive initially to mechanical energy and then to thermal energy in dissimilar Copper – Low carbon steel combination. The emanating pressure in the region of detonation front is transmitted to flyer surface as compressive stress wave and a reflective tensile wave is generated at the bottom surface of the flyer. A dilational wave and shear wave are generated. As the flyer plate moving with the transmitted wave collides with the parent, the available kinetic energy is converted into thermal energy to produce adequate heat to induce plastic deformation thus resulting into a strong metallurgical bond.

Abstract: Explosive cladding is a non-conventional, solid-phase bonding technique in which bonding between two plates is produced by their high velocity collision induced by the use of explosives. Attempts were made to explosive clad Titanium-Stainless steel (SS 304 L) plates (3.5 and 3.0 mm thick respectively). The experiments were designed to analyze the bonding interface parallel to the detonation direction. The presence of intermetallics, caused by the melting at the interface due to kinetic energy dissipation, was observed in some locations. The process parameters of the explosive welding of Titanium-Stainless steel combination are defined using the microstructural observations, microhardness at the interface, the results of X-ray diffraction study. A weldability window is also constructed for explosive welding of Ti /Ss.