Nano-twin in surface modified bainite induced by laser surface modification

• A medium-carbon bainite was surface modified by LRFIT.
• The austenite nano-twin has been detected in the surface modified bainite.
• The surface modified bainite shows a satisfied mechanical properties.

The medium-carbon bainite was surface modified by laser remelting and following isothermal transformation (LRFIT). The austenite nano-twin has been detected in the surface modified bainite by transmission electron microscopy (TEM). The austenite nano-twin films and blocks are embedded in bainitic ferrite with a thickness less than 10 nm, and the twinning occurred on the (1̅11) plane in the [1̅11] direction. The nano-hardness and the creep ratio of the nano-twin has been measured by nano-mechanical tester. The result suggests that, the surface modified bainite with nano-twin shows a satisfied mechanical properties. The nano-hardness and creep ratio of the nano-twin in surface modified bainite is 9.5±0.5 GPa and 7.5±0.3%, respectively.