Interfacial characteristics and properties of a low-clad-ratio AA4045/AA3003 cladding billet fabricated by semi-continuous casting

A low-clad-ratio AA4045/AA3003 cladding billet was fabricated using a semi-continuous casting process and was subsequently extruded indirectly into a cladding pipe. The temperature distribution near the interface was measured. The microstructures, elemental distribution, Vickers hardness around the bonding interface, and the interfacial shear strength were examined. The results showed that the interface temperature rebounded when AA4045 melt contacted the supporting layer. The two alloys bonded well, with few defects, via the diffusion of Si and Mn in the temperature range from 569℃ to 632℃. The mean shear strength of the bonding interface was 82.3 MPa, which was greater than that of AA3003（75.8 MPa）, indicating that the two alloys bonded with each other metallurgically via elemental interdiffusion. Moreover, no relative slip occurred between the two alloys during the extrusion process.

Influence of α/β interface phase on the tensile properties of laser cladding deposited Ti–6Al–4V titanium alloy

Laser cladding deposited Ti-6Al-4V titanium alloy universally shows more complex microstructures,each of which has significant effect on mechanical properties. Of particular α/β interface phase has been observed in this paper under certain conditions. It demonstrates that the influence of the α/β interface phase on the tensile properties is closely associated with dislocations and twin substructure through comparison experiments. The results show that the α/β interface phase hinders dislocation motion and decreases effective slip length. In addition, the twin substructure has been activated in the α/β interface phase during tensile process and has acted somehow like grain boundaries. Therefore, the strength and the work-hardening rate of the laser cladding deposited Ti-6Al-4V titanium alloy have been significantly improved due to the dynamic Hall-Petch effect. Besides, the α/β interface phase leads to more uniform dislocations distribution, which implies that relative lower local concentrated stress will be produced along the α/β interface phase or colony boundary after the same amount of plastic deformation. Moreover,the twinning-induced plasticity effects in the α/β interface phase further increase the plastic deformation capacity. These results in higher elongation for the laser cladding deposited Ti-6Al-4V titanium alloy.It can be concluded that the current work suggests an effective method to simultaneously improve the strength and plasticity of laser cladding deposited Ti-6Al-4V titanium alloy based on the α/β interface phase.

Interfacial phase formation of Al-Cu bimetal by solid-liquid casting method

The solid-liquid method was used to prepare the continuous casting of copper cladding aluminium by liquid aluminum alloy and solid copper, and the interfacial phase formation of Al-Cu bimetal at different pouring temperatures(700, 750, 800 oC) was investigated by means of metallograph, scanning electron microscopy(SEM) and energy dispersive spectrometry(EDS) methods. The results showed that the pouring temperature of aluminum melt had an important influence on the element diffusion of Cu from the solid Cu to Al alloy melt and the reactions between Al and Cu, as well as the morphology of the Al-Cu interface. When the pouring temperature was 800 oC, there were abundant Al-Cu intermetallic compounds(IMCs) near the interface. However, a lower pouring temperature(700 oC) resulted in the formation of cavities which was detrimental to the bonding and mechanical properties. Under the conditions in this study, the good metallurgical bonding of Al-Cu was achieved at a pouring temperature of 750 oC.

Lower limit law of welding windows for explosive welding of dissimilar metals

The influence of explosive charge thickness on the quality of explosive welding of dissimilar metals was investigated.The lower limit law should be followed in the course of explosive welding.Three welding experiments of stainless steel（410S）and steel（Q345R）were carried out in three different kinds of explosive charge thicknesses,namely 15,25and 35mm.Interfaces of morphology and mechanical properties of three samples were observed and tested.It was found that micro and small wavy bonding is mainly formed for charge thickness of 15mm whose strength is the highest with minor deformation and few defects in the interface;small and middle wavy bonding are mainly formed for charge thickness of 25 mm whose strength is comparatively mediocre;big wavy bonding is mainly formed for charge thickness of 35 mm whose strength is the lowest.The cause of high bonding strength of the micro and small wavy interface was analyzed and verified on the basis of the results of Electron Probe Micro-Analyzer（EPMA）tests of three selected samples.