Effect of the microstructure on the low-temperature cyclic crack-growth resistance of high-strength cast irons

Abstract

The regularities of the influence of temperature on the cyclic crack-growth resistance of high-strength nodular cast irons unalloyed and alloyed with nickel are studied in the temperature range 77–293°K for matrices of different structural types (ferritic, ferrite-pearlitic, and pearlitic). It is shown that ferritic high-strength nodular cast irons subjected to high-temperature annealing and high-strength nodular cast irons with the structure of granular pearlite subjected to hardening and high tempering are characterized by satisfactory low-temperature fatigue crack-growth resistance (up to 213°K). The results of mechanical tests are in good agreement with the data of microfractographic analysis. It is demonstrated that the characteristics of cyclic crack-growth resistance of the investigated types of high-strength nodular cast iron are in no case worse than the corresponding characteristics of cold-resistant structural steels frequently used in mechanical engineering.