Study On Deformation Behavior And Strength And Toughness Of Ultrafine Grain Fe-C Alloy

The deformation behavior and strength and toughness of different kinds of ultrafine grained steels are studied from three aspects: the addition of alloy elements,the increase of deformation and the introduction of multi-scale structure.The main research objects are medium carbon chromium-Mo steel after cold rolling deformation and pseudoeutectoid steel obtained by quenching 45 steel at underwater 90 ?.the deformation mechanism of experimental steels was analyzed.The main results are as follows:The structure of cold rolled medium carbon steel is uneven,carbide segregation is serious,and ferrite strip structure is obvious.After adding trace alloying elements such as Cr and Mo,the structure of the experimental steel is obviously improved.The strength and plasticity of the medium carbon Cr-Mo steel have been improved,so the annealing experiments of the medium carbon Cr-Mo steel have been carried out at 600? for different time.The results show that the cold rolled medium carbon Cr-Mo steel annealed for 120 min has the best properties.The dislocation bypass mechanism and the elongation mechanism of Ludes band affect the mechanical properties of materials together.The structure of pseudoeutectoid steel rolled at 500? and 600? is better and the multi-scale structure is more obvious.The results show that the mechanical properties of the steel annealed for 15 minutes are the best after annealing at 600? for different time.Although the strength is lower than that of cold rolled medium carbon Cr-Mo steel,the yield platform is shorter,the uniform work hardening stage is longer,and the overall elongation is better.Plastic deformation transfer mechanism and dynamic recrystallization alternating mechanism affect mechanical properties of materials.Figure 30;Table 6;Reference 48.