Influence of corrosion environments on materials and strength of structures:new approaches and practical applications.

The presented lecture highlights the mechanical, physical and corrosion aspects of the environmentally assisted fracture of structural metallic materials. The methods and testing equipment for corrosion crack growth studies and electrochemical measurements within cracks are described. The relationship between electrochemical state and stress-strain state of pre-fracture zone was derived on the base of received experimental data for the number systems "material-environment". The new method for determining of corrosion fatigue crack growth rate diagrams is presented with taken into account an electrochemical situation in the crack tip. It has been proven that such diagrams reflect the extreme influence of the environment factor on material corrosion fatigue fracture processes and may be recommended as the base for a remaining lifetime calculation of the structure elements that are exploited under environmental conditions. The engineering applications of presented approaches and methods for expert assessment of technical state of heat-and-power engineering pipelines are considered and the examples of calculations of residual life of some structural elements are given with taken into account of the actual data of metal properties and operating conditions of equipment.