Initiation and growth of short fatigue cracks in austenitic Sanicro 25 steel

journal article - other

en

Austenitic heat-resistant stainless steel Sanicro25, often used in energy production installations, was cyclically strained at room temperature, and initiation and growth of short fatigue cracks have been studied. Cylindrical specimens with pre-existing shallow noch were cyclically strained under constant total strain amplitudes, while the surface relief, crack initaition, and short crack growth were observed, in-situ, using optical and electron microscopes. Pestistent slip markings were found to be the principal locations where natural fatigue cracks initiated. The character of the crack paths of short cracks was studied using SEM and EBSD techniques. The results exhibit prevailing transgranular crack growth, ie, along the persistent slip markingswithin the grains. Tho growth of the longest cracks in the central part of the shallow noch was measured for different applied strain amplitudes. Because the coalescence of initiated plays a significant role during crack growth, the use of the "equivalent crack" concept gives adequate results in the description of the crack growth rate. The crack growth law of short crack was established and compared with the Manson-Coffin law of the material.

Austenitic heat-resistant stainless steel Sanicro25, often used in energy production installations, was cyclically strained at room temperature, and initiation and growth of short fatigue cracks have been studied. Cylindrical specimens with pre-existing shallow noch were cyclically strained under constant total strain amplitudes, while the surface relief, crack initaition, and short crack growth were observed, in-situ, using optical and electron microscopes. Pestistent slip markings were found to be the principal locations where natural fatigue cracks initiated. The character of the crack paths of short cracks was studied using SEM and EBSD techniques. The results exhibit prevailing transgranular crack growth, ie, along the persistent slip markingswithin the grains. Tho growth of the longest cracks in the central part of the shallow noch was measured for different applied strain amplitudes. Because the coalescence of initiated plays a significant role during crack growth, the use of the "equivalent crack" concept gives adequate results in the description of the crack growth rate. The crack growth law of short crack was established and compared with the Manson-Coffin law of the material.

austenitic steel, crack growth, crack growth coefficient, crack initiation, EBSD, equivalent crack

07.07.2018

Wiley-Blackwell

1460-2695

41

7

1529–1545

17