Following is tabulated data that were gathered from a series of Charpy impact tests on a ductile cast iron.

(a) Plot the data as impact energy versus temperature.
(b) Determine a ductile-to-brittle transition temperature as that temperature corresponding to the average of the maximum and minimum impact energies.
(c) Determine a ductile-to-brittle transition temperature as that temperature at which the impact energy is 80 J.

Temperature ( C -25 -50 -75 -85 Impact Ener 124 123 115 100 73 52 26 100 -110 125 -150 175