A solid round bar, 25 mm in diameter, has a groove 2

A solid round bar, 25 mm in diameter, has a groove 2.5 mm deep with a 2.5 mm radius machined into it. The bar is made of AISI 1018 CD steel and is subjected to a purely reversing torque of 165 N middot m. For the S-N curve of this material, let f = 0.9. Estimate the number of cycles to failure. If the bar is also placed in an environment with a temperature of 450 degree C, estimate the number of cycles to failure. Number of cycles to failure = Number of cycles to failure at 450 degree C =