Effects of Cooling Rate and Carbon Content on Microstructure and Mechanical Properties of Fe-Cu-Ni-Mo-C Sintered Materials

Partial diffusion pre-alloyed Fe-Cu-Ni-Mo-C powders were used as raw materials,high density compacts were obtained by die wall lubricated warm compaction technology,then sinter hardening process was utilized.Effects of cooling rate and carbon content on the mechanical properties and microstructure of the sintered materials were studied.The results show that the effect of the cooling rate on the mechanical properties of the Fe-2Cu-2Ni-1Mo-xC(x=0.6,1.0) material was dramatic.Tensile strength,yield strength and hardness of the material increased with the increase of cooling rate.At the cooling rate of 2.8℃·s-1,tensile strength,yield strength and hardness of the material with 1.0% carbon content achieved 935 MPa,747 MPa and 298 HB,respectively.And the material with 0.6% carbon content achieved 962 MPa,828 MPa and 285 HB,respectively.Elongation of both the materials decreased with the increasing cooling rate.The microstructure of the materials consisted of martensite,bainite,pearlite and retained austenite.The microstructure mainly contained martensite and bainite at high cooling rate.When the cooling rate decreased,little ferrite was observed.Carbon content had great effect on the martensite type.Plate and lath type martensite structure formed with 1.0% and 0.6% carbon,respectively.