Effects of Material Properties and Initial Stresses on the Durability of Cast Iron Cylinder Heads

Thermal fatigue tests were conducted to find how material properties, operating temperature and initial mechanical stress caused by press fitting of valve seat inserts etc. influence on thermal fatigue cracks of cast iron cylinder heads by means of a simulation test at mainly 100°C. = 350°C cycles.

These tests revealed that the reduction in initial stresses and improvement of tensile strength of material at room temperature are very effective to improve thermal fatigue resistance.

And a new cast iron cylinder head material with high thermal fatigue resistance for heavy duty diesel engines has been successfully developed, utilizing the results of casting experiments by means of experiment design, L16(2[ILLEGIBLE]).

High reliability of new cast iron cylinder heads has been confirmed by accelerated durability bench tests.