This paper presents an experimental and numerical study on two different types of the nodular cast iron EN-GJS-400-18-LT. The experimental procedure includes symmetrical and unsymmetrical strain controlled tests on the cylindrical specimens as well as crack initiation and propagation tests on the compact tension and single edged notched specimens. Different loading regimes are applied, and monitoring of the crack length during the tests is performed by an optical system. Within the framework of numerical investigations an efficient algorithm for modelling of cyclic plasticity is examined. Experimental results show that two material types have significantly different the crack behaviour.