High-temperature mechanical properties of high-boron austenite steels(HBAS)were studied at 850 ℃ using a dynamic thermal-mechanical testing machine.Stereomicroscopy and scanning electron microscopy were used to study the microstructure of the specimens.The effects of boron and carbon contents on the mechanical properties at room temperature and high-temperature of HBAS were investigated.Experimental results show that boride distributes in austenitic matrix in the form of M2B-type boride(M represents Fe,Cr or Mn)after adding boron in the tested steels,and the performances of HBAS at room and high temperatures are effectively improved.The steel hardness at room temperature increases from 200 HV to 302 HV,the tensile yield strength at 850 ℃ increases from 144 MPa to 190 MPa,and the compressive yield strength at 850 ℃ increases from 140 MPa to 168 MPa after adding about 0.55wt.%boron.The experimental results also show that with an increase in carbon content,the boride granules within the HBAS matrix exhibit a round and smooth morphology,and distribute in a discrete manner.The hardness of the alloys increases from 239 to 312 HV; the tensile yield strength at 850 ℃ increases from 165 to 197 MPa and the compressive yield strength at 850 ℃ increases from 166 to 184 MPa with some 0.3wt.%carbon.