|The formation mechanism of characteristic region at crack initiation for very-high-cycle fatigue of high-strength steels|
|Hong YS(洪友士); Liu XL(刘小龙); Lei ZQ(雷铮强); Sun CQ(孙成奇); Hong, YS (reprint author), Chinese Acad Sci, Inst Mech, LNM, Beijing 100190, Peoples R China.
|Source Publication||INTERNATIONAL JOURNAL OF FATIGUE
|Conference Name||3rd International Conference on Characterisation of Crack Tip Fields
|Conference Date||APR 20-22, 2015
|Conference Place||Urbino, ITALY
|Abstract||For high-strength steels, the crack initiation of very-high-cycle fatigue (VHCF) is commonly at the interior of material with fish-eye (FiE) morphology containing a fine-granular-area (FGA) surrounding an inclusion as crack origin, and FGA is regarded as the characteristic region of crack initiation. Here, we carefully examined the micro-morphology of FGA and FiE for two high-strength steels. The results revealed that the microscopic nature of FGA is a thin layer of nanograins. Then we proposed the formation mechanism of FGA: Numerous Cyclic Pressing (NCP) between originated crack surfaces, which causes grain refinement at originated crack wake and therefore the formation of FGA. The results of second set experiment showed that the cases with negative stress ratios exhibit the prevalence of nanograin layer in FGA region and the nanograin layer vanishes for the cases with positive stress ratios, which is a verification of the proposed NCP model. (C) 2015 Elsevier Ltd. All rights reserved.|
Fatigue Crack Initiation
|Corresponding Author||Hong, YS (reprint author), Chinese Acad Sci, Inst Mech, LNM, Beijing 100190, Peoples R China.|
Hong YS,Liu XL,Lei ZQ,et al. The formation mechanism of characteristic region at crack initiation for very-high-cycle fatigue of high-strength steels[C]INTERNATIONAL JOURNAL OF FATIGUE,2016.