The impact and rolling composite friction and wear performance of 0.9C-9Mn-2Cr-Mo medium manganese steel and Hardox400 ( 0.22C-1.6Mn-1.4Cr-Mo) and Hardox500 (0.27C-1.0Mn-0.94Cr-Mo) wear resistant steels have been studied by M2000 multifunction friction and wear testing machine

and the structure transformation and wearing mechanism of steels are analyzed by X-ray difiractometer

SEM and TEM. Test results show that the hot-rolled medium steel has better impact-rolling composite wearing resistance than that of Hardox martensite wear resistance steels ；there is a hardened layer with 1 000μm thickness at impact-wear surface of medium manganese steel

its max microhardness value is up to HV490 and the Rockwell HRC hardness value is up to 53. The main wear mechanism is drill wear failure with local fatigue scale off

and the work hardening and improving wear resistance of medium manganese steel is mainly by dislocation strengthening

deformation twining and martensite phase transformation.