Effects of molybdenum content on the microstructure,flow and densification behaviors of powder sintered steel during compaction
In order to study the effects of molybdenum content on the microstructure of powder sintered steel and its flow and densification behaviors during compression,the compression experiment of powder sintered steel with different molybdenum content were carried out with universal testing machine.Meanwhile,the microstructure of powder sintered steel with different molybdenum content was observed.In addition,the change law of rheological stress in the compression process was investigated and the deformation characteristics of grains and pores were analyzed.The results show that with the increase of molybdenum content,pearlite and ferrite gradually decrease,while bainite gradually increases.When the molybdenum content reaches 0.85％,the microstructure is mainly composed of fine bainite.The flow and deformation behaviors of the powder sintered steel conform to parabolic strain hardening law.With the increase of molybdenum content,its strength increases and its limit strain decreases.At the same strain,the strain hardening rate increases with the increase of molybdenum content.At low strain,it is mainly the compression deformation that caused densification strengthening,while at high strain,it is mainly the plastic deformation that casued work hardening.With the increase of strain,the grains gradually change from equiaxed to lamellar,and the pores are compressed,elongated,and divided into smaller micropores,even compressed closure.
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