Progress in effective characteristics of automotive sheets.

Deep drawing characteristics of cold rolled sheets and aluminum sheets are discussed. First priority is dedicated to the change of strain-rate value during press forming. With rise of strain-rate the deep drawing characteristics could be changed. Mostly uniaxial tensile test results are discussed. Steel material has been also tested by using a newly designed type of biaxial cruciform specimens. The most important basis for comparative evaluation of cold formability is derived from tensile testing. One of the deformation-dependent parameters influencing forming limits is hardness with close relation to elongation, deformation of grains and compressive instability. There were examined changes in micro-hardness of steel during plastic deformation, which is characterized by the area of non-homogenous deformation. Measuring of micro-hardness was realized after uniaxial tensile testing carried out on deep-drawing steel sheets. Study of microstructure and texture development was also provided. Steel and aluminum sheets were measured at SEM (EDS) and steel sheets were evaluated by X-ray diffraction methods.Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi