SCHMIDOVA Eva Univerzita Pardubice

Spoluautoři KONEČNÝ Michal

Low alloy high strength steels are the key materials in the design of safety parts car body structures. Contribution is dedicated to the study of boron steel type of 22MnB5 weldability, with fully martensitic microstructure due to hot stamping technology. The joints strength of the martensitic steels is limited mainly by the part of the heat affected zone with a predominance of a tempered martensite. The main objective of performed analyses is to study the differences in formation of the surface AlSi layer. Those differences are one of the influential metallurgical parameters related to weldability of martensitic steels. The structure of sub layers and changes of their chemical composition were studied as a result of different thermal conditions during heat treatment. The Si-rich zones formation in connection with overheating during austenitization is discussed. The spot welds service durability in automotive structures is strongly affected by the failure mode, in conjunction with different fracture energy. In order to evaluate the failure mode of the spot welds, the shear strength, i.e. shear force to the sheet-sheet interface was chosen as a testing mode. The fractography analyses was performed for documentation of the surface layers in their influence on the failure mode of spot welds. The typical differences in the fracture behavior low alloy martensitic steel are presented.

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