FRACTURE MECHANISMS OF SIX TOP CORROSION RESISTANT Fe AND Ni ALLOYS AT FATIGUE AND STRESS CORROSION CRACKING

Abstract

Two austenitic steels, two duplex steels and two nickel alloys widely used in chemical and power engineering were under study. Slow strain rate tests in various aggressive media and fatigue tests were carried out with aim to evaluate the resistance of the structural alloys to the environment influence and cyclic loading. The resistance was closely related to the qualitative and quantitative aspects of micromechanisms of crack propagation, namely on share of the cleavage fracture, intergranular decohesion and other low energy fracture types. The sensitivity of materials to the brittleness depended on the interaction between microstructure and testing (or service) conditions -especially loading and environment under the given temperature. In the paper, some correlations between fractographic features of specimen fracture and testing conditions are presented.