The high cycle fatigue response of a high V-alloyed powder metallurgy tool steel (AISI 11) with different inclusion sizes was studied. Two materials of this grade at a similar hardness of about HRC 60 were subjected t...The high cycle fatigue response of a high V-alloyed powder metallurgy tool steel (AISI 11) with different inclusion sizes was studied. Two materials of this grade at a similar hardness of about HRC 60 were subjected to axial loading fatigue tests,tensile tests and fracture toughness measurements to investigate their mechanical properties. Large inclusion above 70 μm is indicated to be responsible for the tensile fracture which happens before yielding. The fatigue strength obtained up to 107 cycles is found to decrease from approximately 1 538 MPa to 1000 MPa with the inclusion size increasing above 30 μm. The internally induced crack initiation is mainly attributed to the surface compressive residual stress of 300?450 MPa. Fractographic evaluation demonstrates that the crack initiation and propagation controlling factors of the two materials are almost the same,indicating that the two factors would be insignificantly affected by the inclusion size level. Paris sizes of the two materials both show a tendency to decrease as the ratio of stress intensity factor of crack origin to factor of fish-eye increases. The investigation into the relationship between stress intensity factors and fatigue life of the two materials further indicates that the high cycle fatigue behavior of AISI 11 is controlled by crack propagation.展开更多
Authors produced rapidly solidified T15 high speed steel powders by high pressure(5~ 6MPa) N_a atomization and liquid N_2 cooling,observed and analyzed the morphology and structure of the powders;at the same time,prep...Authors produced rapidly solidified T15 high speed steel powders by high pressure(5~ 6MPa) N_a atomization and liquid N_2 cooling,observed and analyzed the morphology and structure of the powders;at the same time,prepared bulk microcrystalline T15 high speed steel materials by hot extruding or HIPing and hot rolling of the powders,observed and measured the microstructure and performance of the bulk materials.It was shown that rapid solidification may change the solidification characteristics and structure of T15 high speed steel powder and improve the qualities and properties of T15 high speed steel materials.展开更多
Suggestions have been put forward speeding up the development of high-level tool steel and mold steel in China based on the analysis of products and development status of special steel home and abroad. Feasibility and...Suggestions have been put forward speeding up the development of high-level tool steel and mold steel in China based on the analysis of products and development status of special steel home and abroad. Feasibility and necessity to produce high-level tool steel and mold steel by applying the spray forming method in future have been put forward.展开更多
基金Project(2007BAE51B05)supported by the National Key Technologies Research and Development Program of China
文摘The high cycle fatigue response of a high V-alloyed powder metallurgy tool steel (AISI 11) with different inclusion sizes was studied. Two materials of this grade at a similar hardness of about HRC 60 were subjected to axial loading fatigue tests,tensile tests and fracture toughness measurements to investigate their mechanical properties. Large inclusion above 70 μm is indicated to be responsible for the tensile fracture which happens before yielding. The fatigue strength obtained up to 107 cycles is found to decrease from approximately 1 538 MPa to 1000 MPa with the inclusion size increasing above 30 μm. The internally induced crack initiation is mainly attributed to the surface compressive residual stress of 300?450 MPa. Fractographic evaluation demonstrates that the crack initiation and propagation controlling factors of the two materials are almost the same,indicating that the two factors would be insignificantly affected by the inclusion size level. Paris sizes of the two materials both show a tendency to decrease as the ratio of stress intensity factor of crack origin to factor of fish-eye increases. The investigation into the relationship between stress intensity factors and fatigue life of the two materials further indicates that the high cycle fatigue behavior of AISI 11 is controlled by crack propagation.
文摘Authors produced rapidly solidified T15 high speed steel powders by high pressure(5~ 6MPa) N_a atomization and liquid N_2 cooling,observed and analyzed the morphology and structure of the powders;at the same time,prepared bulk microcrystalline T15 high speed steel materials by hot extruding or HIPing and hot rolling of the powders,observed and measured the microstructure and performance of the bulk materials.It was shown that rapid solidification may change the solidification characteristics and structure of T15 high speed steel powder and improve the qualities and properties of T15 high speed steel materials.
文摘Suggestions have been put forward speeding up the development of high-level tool steel and mold steel in China based on the analysis of products and development status of special steel home and abroad. Feasibility and necessity to produce high-level tool steel and mold steel by applying the spray forming method in future have been put forward.
