Multiphase steel with improved impact-abrasive wear resistance in comparison with conventional Hadfield steel

• Multiphase steel with improved impact-abrasive wear resistance was developed.
• Phase transformation of retained austenite under high impact energy during wear caused the enhancement of wear resistance.
• Crack propagation process and the block effect by retained austenite were observed.
• Wear mechanisms of multiphase steel were dominated by press-in particle, micro-voids and delaminated crater.

In the present work, a new multiphase steel and a conventional Hadfield steel (Mn13Cr2) were investigated after being casted in a high-frequency induction furnace. Field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and thermal dilatometer were applied to characterize impact-abrasive wear behaviors, wear mechanisms and phase transformation of the two steels. Results revealed that the multiphase steel with a triplex microstructure (bainite, martensite and retained austenite) had higher tensile strength, micro-hardness and impact-abrasive wear resistance than Mn13Cr2. The main strengthening mechanisms were phase transformation (retained austenite to martensite), grain refinement and high density dislocations for the multiphase steel, and the interaction of twining and dislocation walls were for Mn13Cr2, respectively. The wear mechanisms of the multiphase steel were called as “press-in particle”, “micro-voids” and “delaminated crater”, however those of Mn13Cr2 were called as “adhesion”, “crater” and “micro-crack”. Impact-abrasive wear features like grain deformation, orientated features, crack propagation, voids linking and the block effect of bulk retained austenite to crack branching were observed in the affected layer of the multiphase steel.

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