DocumentCode :
2374435
Title :
Effects of shot peening treatment on very long life fatigue property in ductile cast irons
Author :
Ochi, Yasuo ; Hosoya, Takusaburo ; Masaki, Kiyotaka ; Matsumura, Takashi ; Sekino, Takeshi
Author_Institution :
Dept. of Mech. Eng. & Intelligent Syst., Univ. of Electro-Communications, Tokyo, Japan
fYear :
2001
fDate :
2001
Firstpage :
444
Lastpage :
449
Abstract :
Rotating bending fatigue tests that covered very long life region (up to over 108), were carried out on specimens of three kinds of ductile cast iron (austempered one, ADI, pearlitic one, PDI and ferrite pearlitic one, FPDI) with shot peening (SP) treatment. Influences of the SP treatment on fracture morphology and fatigue property were investigated. It is expected that the SP treatment results not only the high level work hardening and the high level compressive residual stress in the surface layer of the specimens, but also the decrease in casting defects in near surface. Then, they lead a considerable improvement of fatigue strength. Therefore, initial distribution of the hardness in the surface layer of the SP treated specimens was measured. Furthermore, in the PDI-SP and the FPDI-SP materials, it was observed that the sites of the fatigue crack initiation were transferred from the surface to subsurface in the longer life regions, but in the ADI-SP material, the fatigue crack initiation site in whole region of fatigue life was the subsurface. And the S-N diagrams did not show fatigue limit over 107 cycles. So differences in fatigue fracture morphology in the shorter and the longer region of fatigue life were discussed from detailed observation of crack initiation sites with afield emission scanning electron microscopy (FE-SEM)
Keywords :
bending; fatigue cracks; fatigue testing; field emission electron microscopy; fracture mechanics; hardness; internal stresses; iron alloys; scanning electron microscopy; surface treatment; work hardening; FE-SEM; S-N diagrams; austempered specimens; casting defects; compressive residual stress; ductile cast iron; fatigue crack initiation; fatigue crack initiation site; fatigue limit; fatigue property; fatigue strength; ferrite pearlitic specimens; field emission scanning electron microscopy; fracture morphology; hardness; long life fatigue; pearlitic specimens; rotating bending fatigue tests; shot peening treatment; surface layer; work hardening; Cast iron; Casting; Electron emission; Fatigue; Ferrites; Life testing; Residual stresses; Surface cracks; Surface morphology; Surface treatment;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Environmentally Conscious Design and Inverse Manufacturing, 2001. Proceedings EcoDesign 2001: Second International Symposium on
Conference_Location :
Tokyo
Print_ISBN :
0-7695-1266-6
Type :
conf
DOI :
10.1109/.2001.992397
Filename :
992397
Link To Document :
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