Determination of the effects of shot peening with cadmium or chromium plating on the strain fatigue life of NC310 steel.

摘要

The purpose of this thesis was to determine, by controlled strain amplitude fatigue testing and data analysis, the Basquin and Coffin-Manson strain life equation parameters sigma'f, b, epsilon 'f and c of 3 different configurations of NC310 steel: (a) unpeened, unplated bare condition with a neutral residual surface stress state, (b) shot peened after machining (to develop a compressive residual surface stress layer) and then cadmium plated and (c) shot peened after machining and then chromium plated. The basic validity of the testing and data reduction methodology was confirmed by running an incremental step strain control fatigue life test on an unpeened, unplated specimen and then correlating the results with the controlled strain amplitude testing.; As a result of this test/analysis program, it was established that both shot peened and plated configurations lowered NC310's fatigue ductility coefficient "epsilon'" and fatigue ductility exponent "c" values as compared to the unpeened, unplated configuration, while the values for the fatigue strength coefficient "sigma 'f" and fatigue strength exponent "b" were not appreciably affected.