Superplastic materials show huge amount of deformation in low strain rates and temperature above half of melting point. In superplastic forming, estimating the pressure–time diagram and thickness distribution has significant importance. Utilizing numerical methods, the involved parameters in superplastic forming can be optimized for such estimations. In the present paper, the simulation of superplastic forming of a cup-shape part is demonstrated, assigning the proper constitutive equation. In the following, a noble approach for estimating the pressure–time diagram, using finite element method, is presented and by using this approach, the optimum pressure–time diagram for the forming process is estimated while the effects of process parameters such as friction index and strain rate on pressure–time diagram and thickness distribution is evaluated. Simulation results are compared with other researches results, which show satisfactory agreement.  Manuscript profile

Today, in sheet metal forming processes, a new concept of fabricating consolidated sheets or in other words Tailor Welded Blanks emerged. Friction Stir Welding is one method for manufacturing TWBs and has numerous advantages over fusion welding methods for joining aluminum sheets. In the present study, TWBs made by friction stir welding of 6061-T6 and 5754-O aluminum alloys were studied. The effects of different tool rotational speeds and welding speeds on the mechanical properties and microstructural characteristics of dissimilar joints were evaluated. The results showed that in an appropriate range of speeds combinations, an optimum rotational speed exists at which maximum strength is achieved. Regarding welding speed, greater strength is attained at higher speeds. The microstructural analysis confirms that an increase in welding speed will result in grain size reduction and consequently higher tensile strength. It is observed that above the optimum rotational speed, the grain size of the nugget zone increases which results in decreasing tensile strength. With regard to elongation, it is found that despite the grain growth of the nugget zone at a higher ratio of tool rotational speed to welding speed, the elongation improved due to the dominant material existing in the weld zone. Positioning Al 6061 on the advancing side of the dissimilar joints leads to improved mechanical properties compared with positioning on the retreating side. It is notable that the degree of such improvement in ductility is much more remarkable than strength, which is valuable regarding formability concerns. Manuscript profile