Selective modification of dual phase steels by laser action

Project title:"Selective modification of dual-phase steels by laser action". Within the scope of this project, it is planned to develop a simulation model for laser treatment of dual-phase steels as well as an extension of possibilities of standard finite element programs by user-defined scripts for the simulation of thermal processes due to laser irradiation. Furthermore, it is intended to perform thermal process calculations which take into account changes in the absorption coefficient and investigations of laser beam shaping for a more precise spatial power distribution. The influence of a precisely defined and localized laser beam, which is formed by diffractive optical elements, on the structure of dual-phase steels will be investigated. Special features of laser processed materials with a ferritic- martensitic structure will be analysed as well as changes of their structures and properties after laser treatment. Within the framework of the research project, it is planned to investigate laser processed samples by means of metallography, whereby the laser radiation was formed by diffractive optical elements, and to analyze changes of material structures. Design of experiments with the surface response method will be used for test planning to determine interdependencies of processing parameters. Due to the combination of strength and formability, dual-phase steels have great potential for improving the crash resistance of vehicles and can also contribute to an overall weight reduction of cars. The planned investigations are therefore of great interest for real world applications especially in the automotive industry. Alternating, localized areas of high and low material strength in a car body can contribute to an increase of the passive safety of modern vehicles. Within the scope of the project, it is planned to carry out investigations to obtain local, alternating areas of varying strength of dual- phase steels by means of laser treatment for the first time. New technical solutions offer the possibility to change the distribution of the power density of the laser radiation on the surface of materials with high accuracy. Another very innovative aspect of this project is the precise modelling of thermal processes due to laser irradiation. For this purpose, standard programs for finite element calculations will be extended with the help of user-defined scripts. A major difference between the present project and previous investigations is that, in addition to a well defined spatial localization of the laser radiation, power densities are to be investigated. Analyses of structural changes in the materials are accompanied by experimental research based on design of experiment about the influence of the laser beam on metallic materials.