Grain refinement by pearlitic-type constituents in Co–28Cr–5Mo–0.3C alloy

In this study, an attempt to investigate an alternative method for grain refinement in Co–28Cr–5Mo–0.3C alloy by microstructural transformation, from pearlitic-type constituents to globular austenite structure has been made. During combined aging treatment (at 850 °C for 10 h + 980 °C for 20 min) new grains nucleated from the interfaces of pearlitic-type constituents and grew to form globular equiaxed austenitic structure (with almost 1/10 of their initial grain size). X-ray diffraction patterns showed that the microstructure after reversible treatment is the same one resulted from solution treatment. The suggested method studied promoted a microstructure formed by a fine equiaxed grain distribution with 60 μm average grain size. Moreover, tensile properties after transformation showed excellent strength combined with good ductility.

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► Lamellar pearlitic-type constitutes used as austenite grain refinement.
► Grains nucleated from the interfaces of lamellar pearlitic-type constitutes.
► Tensile properties after transformation showed excellent strength with good ductility.