An experimental investigation of propagation the semi-elliptical surface cracks in an austenitic steel

• Comparative fatigue studies of 1.4541 steel in three states were conducted.
• We determined influence of operation environment on structure and mechanical properties.
• Fatigue tests were conducted under load conditions of real chemical pipeline.
• There was proposed modified measurement method of two-dimensional fatigue cracks.

This paper presents the results of experimental studies of propagation of the semi-elliptical cracks in 1.4541 austenitic steel commonly used for the construction of the industrial pipelines. The work includes the results of studies of the structure and mechanical properties of 1.4541 steel used to build new pipeline sections and steel after many years of service. Fatigue crack growth analysis was performed by using the method of electrical potential drop (EPD). In order to confirm correctness of the electrical potential drop measurement method a two other experimental methods were used in comparative studies, staining of fatigue fracture and using a strain propagation gauge. Elaborated EPD measurement methodology enables a continuous recording of the dimensions of propagating semi-elliptical cracks, both under variable tension and under constant bending, which was confirmed during the tests.