Paper presents the analyses of high strength steels type of MnB5, widely used for auto-body passive safety parts. Different surface treatment towards to weldability optimization was subjects of performed experiments. Diffusion processes in surface layer due to variable heat treatment were observed as a substantial influence on strength of welding joints; prospective influence on microstructure and dynamic response outside heat affected zone was also examined.Current development trends in this area lead to limitations for standard mechanical tests. Variable mechanical response of a particular constructional parts is required for energy flow during crash, so the local dynamic response including energy consumption during deformation and destruction needs to be analyzed. The rate-dependent behavior was examined at strain rates approaching operational relevant strain-rates, i.e. at strain rates ranging from quasi-static to 1000 s-1. Behavior of steels in the sub-Hopkinson regime revealed the most influential strengthening effects, and also the higher sensitivity to phase heterogeneities. The present study employed servo-hydraulic tensile testing machine and the hammer loading system to obtain precise uniaxial loading and also decisive information about energy consumption.Keywords: martensitic steels, dynamic fracture behavior, high strain rate
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