Effect Of Fine Particle Bombarding On Thermal Fatigue Property Of Tool Steel For Die Casting

Author:  S Takagi, M Kumagai, T Satsuta, A Sano, E Shimodai
Source:  Conf Proc: ICSP-10 Tokyo, Japan 2008
Doc ID:  2008075
Year of Publication:  2008
ABSTRACT Effect of the fine particle bombarding (FPB) process, which makes particles of several tens microns in diameter impact at high speed, on the thermal fatigue property of the tool steel for die casting (JIS-SKD61) was investigated. FPB processed specimens exhibited superior thermal fatigue properties as compared with that of not processed specimen. i.e. both a number and depth of heat cracks obviously decreased in the FPB processed specimens after the thermal fatigue test that the surface temperature of the specimens was gone up to 843K and down to 373K cyclically for 2,000 times. TEM observation revealed that nanocrystalline structure was produced near the surface of specimen by FPB process and that serious grain coarsening did not occur in the nanocrystalline structure even after annealing at 843K. Therefore it is considered that grain refinement by FPB process contributed to prevent initiation and grows of heat cracks. KEY WORDS heat crack, nanocrystalline structure, severe plastic deformation

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