Background: In this study, the effect of processing parameters on the mechanical properties of friction-stir-welded polyamide (nylon 66) sheets is investigated. Methods: Commercial polyamide sheets with the dimension of 250 × 150 × 8 mm are used in experimentations. The processing parameters considered in the welding include: rotational speeds in five levels and traverse speeds in three levels. Tensile and impact tests are performed in order to evaluate mechanical behavior of welded sheets. Full-factorial design of experiments and also analysis of variance was performed in present study. Results: Results show that when rotational speed increases, weld strength first increases and then decreases. In other words, there is an optimum rotational speed in which the welded samples could obtain the highest tensile Strength. Regarding the traverse speed, weld strength decreases with increasing of the traverse speed. Conclusions: Obtained results show a significant relationship between considered properties and processing parameters through an analysis of variance (ANOVA) study.

Resistance spot welding (RSW) is a complicated process, which involves the interaction of electrical, thermal, mechanical, and metallurgical phenomena. In this research we used two types of material (UNS G10050 carbon steel and UNS C10010 copper) and welded them in similar and dissimilar condition with four variables welding current, pressure, squeeze time and welding time. The results of the tensile-shear force were analyzed statistically by the Design of experiments (DOE) utilizing Taguchi method. Tensile-shear test used for counting the strength of the joint, maximum strength was found in similar joining condition for carbon steel, also it is interesting to note that the strength of dissimilar joint is stronger than copper joining in similar condition.

The resistance spot welding (RSW) method was used to join aluminum alloy AA 1050 and copper alloy UNS C50100 sheets. Mechanical properties of the joints were examined. The influence of welding process parameters on tensile shear force of the joints was discussed. The design of experiments (DOE) method was used to analyze the influence of welding parameters on the mechanical properties of the joints. Three RSW parameters were used: welding current, squeeze time, and welding time. The results showed that the joint shear stress increased with increasing the welding current until a value of 12000 Amp. Then the shear stress decreased. The tensile shear stress increased with increasing the welding and squeeze time. As a consequence, it can be possible to weld copper with aluminum by RSW.