Q.Z. Cai
,
B.K. Wei
,
Y. Tanaka
金属学报(英文版)
The acicular ferrite in austempered ductile iron (ADI) matrix around graphite was
corroded preferentially in wet condition, promoting crack origination and propagation
and resulting in the disappearance of ADI fatigue limit. ADI fatigue strength was
gradually reduced with increasing the time of test and was reduced by 50% in wet
condition at 10+7 cycles compared with the fatigue limit in dry condition. The fatigue
strength variation of ferritic ductile iron in wet condition was similar to that of ADI.
The ferritic ductile iron, however, has better corrosion resistance so that the fatigue
strength was lowered only by 10% in wet condition at 10+7 cycles compared with the
fatigue limit in dry condition. On the other hand, the fatigue limits of ADI and ferritic
ductile iron were dropped by 32% and 25% in tap water dipping 480h/dry condition
respectively compared with those in dry condition. The reduction of fatigue limit was
attributed to corrosion pits formation correlated with stress concentration, resulting
in origination and propagation of fatigue crack.
关键词:
austempered ductile iron
,
null
,
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