-Proceed as in Prob. 11.16, but use the data for 17-4 PH stainless steel in Table P11.17.

For RQC-100 steel, some da/d N versus

K data at three different positive R-ratios are given in Table P11.18. (a) Plot the given da/d N versus

K data on a log–log graph, and draw a set of parallel lines through the data, one for each R value. Is it reasonable to represent the data by such a set of parallel lines? (b) If yes, then employ all of the data in a single multiple regression fit based on Eq. 11.21, to obtain values of the constants C0, m, and γ for the Walker equation. (c) On log–log coordinates, plot da/d N versus the equivalent values

K, showing both values from the data and the line from your fit. Are the data consolidated? Are they represented well by the line?