Cast iron materials are used, in many cases, for cylinder cover of small and medium bore diesel engines and thermal fatigue strength of these cylinder covers becomes an important consideration.
The cast iron materials, however, are of complicated characteristics, and it is difficult to evaluate thermal fatigue strength of the materials under actual service conditions.
Conclusions of this study are summarized as follows;
(1) “Thermal fatigue parameter Lth”which was derived to evaluate thermal fatigue strength of the materials, can be used in the material selection.
(2) When the thermal fatigue strength of cylinder cover materials was estimated by using“Thermal fatigue parameter Lth”and also by thermal fatigue tests, pearlitic ductile cast iron material have higher thermal fatigue strength than ferritic ductile cast iron materials, and the latter have customarily been used for cylinder covers by majority of diesel engine manufacturers.
(3) By way of trial, the pearlitic ductile cast iron cylinder covers for engine with 450 mm in bore size were produced, and then are being successfully used on board 2 refrigeration ships for testing.
The above suggests that pearlitic ductile cast iron cylinder covers have a possibility of practice marine application.