# Solution Essay

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PROBLEMS _CH8_ 8.12, 8.20, 8.33 ASSIGNMENT CHAPTER 8 8.12 Following is tabulated data that were gathered from a series of Charpy impact tests on a ductile cast iron. |Temperature (°C) |Impact Energy (J) | |–25 |124 | |–50 |123 | |–75 |115 | |–85 |100 | |–100 |73 | |–110 |52 | |–125 |26 | |–150 |9 | |–175 |6 | (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. Solution (a) The plot of impact energy versus temperature is shown below. [pic] (b) The average of the maximum and minimum impact energies from the data is [pic] As indicated on the plot by the one set of dashed lines, the ductile-to-brittle transition temperature according to this criterion is about –105°C. (c) Also, as noted on the plot by the other set of dashed lines, the ductile-to-brittle transition temperature for an impact energy of 80 J is about –95°C. PROBLEM 8.20 8.20 The fatigue data for a ductile cast iron are given as follows: |Stress Amplitude