The 0. 14C-5Mn steel (/%: 0. 14C

5. OMn

0. 008P

0. 002S

0. 003 ON) is melted by a 50 kg vacuum induction furnace and roiled to 4 mm pate (finishing temperature 1 000 °C

air cooling). The structure and mediatic properties of 4 mm plate of 0. 14C-5Mn steel annealed at 550 ~ 650 °C for 6h are studied by scanning electron microscope

X-ray diffraction analysis and uniaxial tensile test. Results show that the austenite is produced in annealing process of 0. 14C-5Mn steel (occurring transformation-induced plasticity-TRIP effect)

and with increasing annealing temperature the volume fraction of austenite increases and the elongation and product of tensile strength to elongation increase obviously. With annealing at 650 °C for 6 li the austenite fraction in steel is up to 30. 11%

the tensile strength of steel is 945 MPa and the product of tensile strength to elongation is 37. 3 GPa%.