Chapter 5, Problem 42QTP

The endurance limit (fatigue life) of steel is approximately one-half the ultimate tensile strength (see Fig. 2.16), but never higher than 100 ksi (700 MPa). For iron, the endurance limit is 40% of the ultimate strength, but never higher than 24 ksi (170 MPa). Plot the endurance limit versus the ultimate strength for the steels described in this chapter and for the cast irons shown in Table 12.3. On the same plot, show the effect of surface finish by plotting the endurance limit, assuming that the material is in the as-cast state. (See Fig. 2.29.)