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For improving production efficiency and saving energy, various manufacturing technologies for integrating solid-state joining and plastic forming processes have become hot topics in recent years. Hot deformation and solid-state bonding of materials are essences for the integration of solid-state joining and plastic forming processes. This study compared the hot deformation and solid-state bonding behavior of an Al-Mg-Si alloy at the temperatures ranging from 673 to 803 K and the strain rates ranging from 0.001 to 10 s−1 using conventional hot isothermal compression tests (CHICT) and hot isothermal compression bonding tests (HICBT). The flow stress behavior of the material during CHICT and HICBT was compared, and a constitutive equation was established based on the true stress-strain curves obtained from HICBT. The evolution of grain structure and bonding interface in the processes of hot deformation and solid-state bonding was investigated. Furthermore, the quantitative relationship between the interfacial bonding degree and the temperature and strain rate was established, and the relationship between the bonding degree and the mechanical properties of the welds was discussed. A new parameter, RSS, was proposed to evaluate the solid-state weldability of materials. [ABSTRACT FROM AUTHOR]

During the extrusion process of aluminum alloy, the ram velocity should be well controlled, since it is an important parameter affecting the profile quality and extrusion productivity. The effects of ram velocity on conventional porthole die extrusion have been investigated by some researchers, while its influence on pyramid die extrusion has not been fully clarified. Thus, in this study, the pyramid die extrusion process for producing a hollow rectangular aluminum tube was comprehensively investigated by performing analysis of steady state, transient state, and billet skin tracking. Importantly, the effects of ram velocity on some evaluation parameters of pyramid die extrusion, such as the material flow behavior, extrudate temperature, extrusion force, transverse weld, quality of longitudinal weld, and back end defect, were overall investigated. The results show that the flowing velocity, extrudate temperature, extrusion force, and welding pressure tend to increase as the increase of ram velocity, while the length of transverse weld is reduced at higher ram velocity. However, the effect of ram velocity on the back end defect is quite slight. Moreover, the advantages and shortcomings of pyramid die were also discussed by comparing with the conventional porthole die. [ABSTRACT FROM AUTHOR]

The appropriate die design for multi-hole extrusion is still a challenging task because of the complicated circumstances and large material deformation during extrusion process. In the present study, the material flow during multi-hole extrusion process for producing a hollow and thin-walled profile was revealed by means of numerical simulation based on the Arbitrary Lagrangian Eulerian (ALE) method. The effects of eccentricity ratio, shape of the second-step welding chamber, and uneven bearing length on the exit velocity distribution of extrudate were synthetically investigated, and a two-hole porthole die was designed accordingly. The exit velocity and temperature on the extrudate in this optimized die were analyzed and compared with the initial die, and it was found that both of them exhibit better uniformity, which is beneficial for the enhancement of product quality. Through performing the current work, a logical and effective route for designing multi-hole porthole die was proposed as the guidance for die designers. [ABSTRACT FROM AUTHOR]