抄録
In order to investigate the characteristic of the low cycle fatigue strength of gray cast iron, pulsating tension fatigue tests have been carried out by using notched and unnotched plate specimens of various sizes.
The primary results obtained are summarized as follows:
(1) The fatigue crack propagating rate dlc/dN is proportional to the n-th power of the stress intensity factor range ΔK regardless of the dimension of notch and the stress level. And the value of n is 7.5-9.1.
(2) The apparent fracture toughness KIC is hardly affected by the dimension of notch, but depends on the size of specimen. That is, KIC of a large specimen is higher than those of smaller ones.
(3) The notch factor β is about 1.1 in the case of the hole notch, and about 1.2-1.3 in the case of the key hole notch.
