Selective modification of dual phase steels by laser action

funded by: FWF, opens an external URL in a new window 

project number: I3920-N36

project end: December 2021

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.

Within this project it is planned to develop simulation models of laser treatment of dual phase steels and to extend the capabilities of a standard finite element program by user-defined scripts for the simulation of thermal processes during laser irradiation. In addition, thermal process calculations taking into account changes in the absorption coefficient and investigations of the laser beam shaping for a more precise spatial power distribution are performed. Furthermore, the influence of the impact of a precisely defined and localized laser beam, which is shaped by diffractive optical elements, on the structure of dual-phase steels is investigated. The laser processing of materials with a ferritic-martensitic structure is investigated in detail as well as the resulting material structures and properties after laser treatment.

During the implementation of the research project it is planned to investigate laser processed samples by means of metallographic analysis, whereby the laser radiation was formed by diffractive optical elements, and to analyse the change of the metallic material structures. By means of statistical experimental design, dependencies of the processing parameters can be recorded. Due to the combination of high strength and good formability, dual-phase steels have great potential for improving the crash performance of vehicles and can also contribute to weight reduction. The planned investigations are therefore of great interest for real applications - especially in the automotive industry. Changing local areas of high and reduced strength of materials in a car body make it possible to increase the passive safety of modern vehicles. Within the scope of the project, it is planned to carry out investigations for the first time to achieve local alternating areas of different strength of dual-phase steels by laser treatment. New technical solutions make it possible to selectively modify the distribution of the power density of the laser radiation on the surface of the material. A further, very innovative aspect of this project is the precise modeling of thermal processes under laser irradiation. For this purpose, standard programs for the calculation of finite elements using user-defined scripts are extended. An essential difference of this project compared to previous investigations is that in addition to the spatial localization of the laser radiation also power density distributions are to be investigated. Based on statistical experimental design, the experimental investigations of the effect of a laser beam on metallic materials are to be accompanied by analyses of the structural changes.