High cycle fatigue, crack propagation resistance and fracture toughness in ship steels

In this paper, two grades of steel, viz., plain carbon steel and low alloy steel used in naval ships have been selected for studies on high cycle fatigue, crack propagation, stress intensity and crack opening displacement (COD). Specimen for high cycle fatigue was prepared as per IS: 1608. High cycle fatigue was carried out up to 50,000 cycles at 1000 kgf to 2000 kgf loads. Up to 2000 kgf loads, both the materials were observed within elastic zones. A number of parameters, including stress, strain and strain range, which indicate elastic behaviour of steels, have been considered. Low alloy steel specimen was prepared as per ASTM standard: E-399 and subjected to 5,00,000 cycles. Crack propagation, GOD, stress intensity, load-cycle variations, load-GOD relation, and other related parameters have been studied using a modern universal testing machine with state-of-the-art technology.