INFLUENCE OF SURFACE ROUGHNESS ON FATIGUE AND CORROSION FATIGUE BEHAVIOUR OF 0.12 C-12Cr-2.5Ni-1.8Mo-0.3V STEEL

摘要

The behaviour in fatigue and corrosion fatigue caused by rotating bending fatigue of a Cr 12 % steel is determined for different surface roughness and residual stresses (or), obtained by machining, polishing, tumbling and shot peening. In the absence of σ_R, the fatigue limit of the material is : σ_D = 440 MPa in the air at 3.10~7 cycles and σ_(DC) = 200 MPa in an aerated solution of H_2O + 1 g/l NaCl. It appears to be difficult to directly obtain through machining, a state of homogeneous σR compression. At he rough stage of machining, σ_D is reduced from 400 to 300 MPa with the simultaneous rise of aR and the roughness (R_(max)=4 to 20μ/m).