A method of forming and a blank therefor, in which the blank comprises a parent body and an insert, at least one of which is made of a material which possesses superplastic properties. The insert is joined to the parent body by friction stir welding. The primary purpose of the invention is to provide a blank for a forming process during which some parts of the blank are required to deform to an extent which requires superplastic properties, whereas the remaining parts of the blank are deformed to a lesser extent.
