Having read the report several times I failed to identify the issue raised! On page 10 of the report, S170 cast steel shot with a hardness of Rc 65 peening to 10A gave a mean cycles to failure of 25,086 for the 6 samples tested. On page 11 of the report, S170 ceramic shot with a hardness of MOH 6-7 peening to 10A gave a mean cycles to failure of 20,189 for the 6 samples tested.
The data is not consistent with: "The average fatigue failure was about 25% higher in the samples peened with cast steel shot." Fatigue failure rate is lower the larger the number of cycles to failure!
