Effect of Low Temperature on Fatigue Crack Growth Rate of HSLA Steel

The material used in this investigation is an ASTM A633 Grade C, HSLA steel which is a normalized high-strength low-alloy steel. Which is widely used structural steel for welded, riveted or bolted construction requiring superior notch toughness performance at low ambient temperatures. Typical applications for A633 Gr.C include utility pole base plates, off-shore oil and gas platforms, construction equipment frames, electric shovel dipper handles and suspension components. Hence the importance of predicting fatigue life and its performance of at low ambient temperature is very important. In the present investigation an attempt has been made to study the effects of low-temperature on fatigue crack growth behavior of HSLA steel. Tests were carried out using CT specimens, at low temperature under mode-I condition. It is observed that crack growth rate increases with decreasing temperature upto DBTT. Further reduction of temperature registered increase in crack growth rate in most of the cases. The behavior has been explained on the basis of impact energy of the material at different temperature, fractographic observations as well as relative humidity in the cold chamber. Exponential model has been developed to predict fatigue life at low temperature. The predicted results of the models were found to be in good agreement with the experimental data