Dependence of micro-hardness on deformation of deep-drawing steel sheets

As the automotive industry addresses environmental concerns, the problem of fuel consumption and weight reduction has come to the fore. Reducing the weight of automobiles is one of the primary means by which their fuel consumption is lowered. The two basic approaches are in automotive design and in materials selection, and they are closely related. There has been strong competition from the steel industry, which for obvious reasons would prefer that steel be retained as the primary automotive material. On the steel side, one primary problem is to find new ways to design automotive components that permit the use of less material while not sacrificing strength and safety. It is increasingly important to able to characterize material behavior during processing. The most important basis for comparative evaluation of cold formability is derived from tensile testing. To describe the different material properties with regard to the forming behavior more easily, parameters are inferred from the different testing methods. The tensile test provides known characteristic values such as the tensile strength R., the yield stress R-p0.2, the planar and normal anisotropy r-values and the strain hardening exponent. Research work being presented examines changes in micro-hardness of steel during plastic deformation and thereby characterizing the area of non-homogenous deformation. (C) 2002 Elsevier Science B.V. All rights reserved.