Local Strain Hardening of Metal Components by Means of Martensite Generation
The emphasis, in respect of content regarding the here presented project, lies within the production of localized reinforcements, by means of transformation-induced α’ martensite formation in solid and sheet metal components. During the forming process of metastable austenitic steels, high-strength martensite areas, next to ductile austenitic regions, are to be adjusted to enable the production of load-adapted components. To this end, extensive basic analyses are also necessary in order to determine the description of the mechanical behavior of α’-martensite structures, as well as to determine the extension of the numerical simulation as regards the structural change. The results achieved within the area of steel forming include the development of a temperable deep-drawing die (T = -35 °C until T = 100 °C) that carefully facilitates structural conversion at a constant forming-degree. Moreover the crash performance, based on transformation-induced martensite structures is improved. So-called Forming Curves (FCs) were developed as a new approach towards the material characterization of structured steel. In bulge forming components, comprised of chrome and nickel steels as well as manganous hard steel, martensite was specifically generated under the use of differing forming parameters. The tool design was aided by Finite Element Analysis (FEA). Moreover, fundamental simulations were carried out in order to calculate the structural change. The modification and extension of a semi-analytical model of the material followed so that the martensite content could be calculated in the previously examined sheet components, as in the massive forming.
Heinz Palkowski and Kai-Michael Rudolph
B. A. Behrens et al., "Local Strain Hardening of Metal Components by Means of Martensite Generation", Advanced Materials Research, Vol. 137, pp. 1-33, 2010