Manganese-rich austenitic twinning-induced plasticity(TWIP)steels with high strength and exceptional ductility have received much attention in the past two decades.Tremendous efforts have been made to explore their unusual hardening behavior which involves complex dislocation-twin interaction,dislocation-dislocation interaction,dislocationgrain boundary interaction and dislocation-solid atom interaction.Nevertheless,the individual hardening effects of twins,dislocations,grain boundaries and solid solution to the high strength of TWIP steels are still unclear.In order to answer this question,the flow stress of a TWIP steel wasexperimentally decomposed into the respective contributions of twins,dislocations,grain boundaries and solid solution in the present study.For the determination of forest hardening,synchrotron X-ray diffraction experiments with line profile analysis were carried out to measure the dislocation density.It is found that the yield stress of the present TWIP steel is controlled by solid solution and grain boundary hardening,which contribute to 238.3 and 238.5 MPa of the flow stress,respectively.After yielding,the work-hardening rate is dominated by dislocation evolutionwhich accounts forup to 922 MPa at a true strain of 0.4,equal to~60%of the flow stress.In comparison,twins contribute to 118 MPa at the same true strain,equal to~8%of the flow stress.In other words,twins only have minor effect on the flow stress,in contrast to the current understandings in the literature.