Microstructure evolution and statistical analysis of Al/Cu friction-stir spot welds

Abstract

In this paper, friction-stir spot welding (FSSW) is performed on 3 mm thick AA1060 and C11000 using different process parameters and tool geometries. The microstructure-and the microhardness-profile analyses were conducted and the probability distribution function (PDF) of the obtained microhardness values was determined. Optical images showed a good material mixing in most of the spot welds produced, whereas the energy-dispersive-spectroscopy (EDS) analysis showed the presence of intermetallic compounds. Microhardness results revealed that process parameters and tool geometries have significant effects on the distribution of microhardness values in different locations of the produced spot welds. Furthermore, goodness-of-fit values showed that most of the R 2 values ranged between 0.8842 and 0.9999, which indicated how well the model fits with the experimental data. On the other hand, the residuals comprised positive and negative runs which also indicated the existence of a certain correlation with the experimentation. Keywords: aluminium, copper, friction-stir spot welding, statistical analysis V prispevku je predstavljeno vrtilno-torno to~kovno varjenje (angl. FSSW) na 3 mm debeli plo~evini AA1060 in C11000 z uporabo razli~nih procesnih parametrov in razli~no geometrijo orodij. Izvedene so bile analize profila mikrostrukture in mikrotrdote in dolo~ena je bila porazdelitvena funkcija verjetnosti za dobljene vrednosti mikrotrdote. Posnetki so pokazali dobro me{anje materiala na ve~ini izdelanih to~kovnih zvarov, medtem ko je EDS-analiza pokazala prisotnost intermetalnih spojin. Meritve mikrotrdote so pokazale, da imajo procesni parametri in geometrija orodij pomemben vpliv na porazdelitev mikrotrdote glede na razli~ne lokacije izdelanih to~kovnih zvarov. Nadalje je serija opazovanj oz. ocena pokazala, da je ve~ina R2 vrednosti rangiranih med 0,8842 in 0,9999. To potrjuje, da se model dobro ujema z eksperimentalnimi podatki. Po drugi strani pa razlika med pozitivnimi in negativnimi cikli ka`e na obstoj dolo~ene korelacije s preizku{anjem.

Friction Stir Spot Welding of Aluminum and Copper: A Review

“…In addition, at high rotational speeds, the softening of Al and Cu materials caused by high heat generation is more serious, and the material flow is more severe, which also makes it easier for large Cu bulks to separate from the Cu matrix and disperse into the Al side (see Figure 3 in ref. [47]). flow is more severe, which also makes it easier for large Cu bulks to separate from the Cu matrix and disperse into the Al side (see Figure 3 in ref.…”

“…flow is more severe, which also makes it easier for large Cu bulks to separate from the Cu matrix and disperse into the Al side (see Figure 3 in ref. [47]).…”

“…It is noteworthy that, in the study by Mubiayi et al [35], due to the Al particles having been dragged into the Cu material, a hardness decrease at the Cu side of SZ was observed. In addition, they also systematically investigated the influence of the probability distribution function (PDF) histogram analysis method on the hardness of different regions of Al-Cu FSSW joints, with the results showing that the profile of the welding tool and the process parameters have a significant effect on the joint hardness distribution [47].…”