Micro-tensile behaviour of low alloy steel with bainite/martensite microstructure

Synopsis : Micro-tensiletestingcombinedwithanalysisusingacrystalplasticityfiniteelementmethod(CPFEM)wasemployedtoelucidatethede-formation behaviour of bainite/martensite structures of a low alloy steel. The bainite single phase specimens exhibited habit-plane-orienta-tion-dependent yielding similar to the martensite single phase specimens. In the bainite/martensite specimen, deformation concentrated in the bainite region oriented favourably for the in-habit-plane slip, leading to low ductility fracture. With consideration of the habit-plane-orien-tation-dependent yielding, the present CPFEM analysis successfully reproduced the anisotropic plastic deformation behaviour of the single phase steels obtained in the experiments. The numerical result for the bainite/martensite specimen showed slip localization in the bainite region and stress concentration near the interphase boundary. This suggests that the interphase boundary can be a site for the fracture origin.

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