Abstract: Effect of annealing temperature on microstructure and properties of hot rolled 0Cr25Al5 wire steel was studied by means of microstructure analysis and molecular dynamics simulation.The results show that with the increase of temperature,the grain size is increased gradually and tends to be stable,but the percentage elongation and percentage reduction of area after fracture is decreased sharply at 950 ℃.The OM and SEM microstructure of the specimens annealed at 800 ℃ or 950 ℃ have no obvious difference.And the free energy of 0Cr25Al5 steel ternary system is calculated by molecular dynamics simulation.With the increase of ordered phase size of FeAl with B2 structure or Fe₃Al with DO3 structure,the free energy of the system is first decreased and then increased,and with the increase of annealing temperature,its minimum value is moved to the direction of the decreasing size of ordered phase particles.At the high temperature of 1273 K,the size of ordered phase particles is still remained about 60 nm.Therefore,it is speculated that the decrease toughness of 0Cr25Al5 steel in the temperature range above 950 ℃ is due to the ordered phase of FeAl with B2 structure or Fe₃Al with DO3 structure at about 60 nm,which is independent of grain size.Therefore,for the kinds of steels,to eliminate defects,a low temperature annealing shall be adopted to make the recovery of the matrix,which can inhibit from the diffusion of matrix atoms.

Key words: 0Cr25Al5 wire steel, annealing temperature, ordering phase, molecular dynamics simulation