**1. Introduction**

In the late 1960s, pioneer works by Keeler [1] and Goodwin [2] established the initial procedures for characterizing metal sheet formability based on the use of circle grid analysis (CGA) techniques, allowing for the determination of the in-plane strains on the surface of sheet metal formed parts. Later, in the early 1980s, Embury and Duncan [3] introduced what they called 'formability maps', currently known as forming limit diagrams (FLDs) [4], allowing for the plotting of the values of the critical strains at the onset of failure, along with the strain distribution attained at the forming process of a certain industrial part or component. These research works allowed the creation of the current framework for the analysis of sheet metal forming, also extensible to tube forming.

On the other hand, the current manufacturing industry focuses on the production of light-weight components with better mechanical properties, always fulfilling the increasingly more strict environmental requirements. These challenges have resulted in the requirement for the development of manufacturing processes in general, including, evidently, those devoted in particular to the development of thin-walled metallic shapes, as is the case with tubular and sheet metal parts and devices.

Thus, this Special Issue is devoted to research work in the field of sheet metal forming, tube forming, and their applications, including both experimental and numerical approaches and using a variety of scientific and technological tools, such as the abovementioned FLDs, analysis on formability and failure, strain analysis based on circle grids or digital image correlation (DIC), and finite element analysis (FEA), among others.

The contributions presented in this Special Issue are discussed in the following section, and were originally invited to deal with recent studies in the field of tube and sheet metal forming processes and their main applications within different high-tech industries, such as the aerospace, automotive and medical sectors, among others.
