ABSTRACT
Using the results shown in Fig. 10 the effect ofthe phase stresses on the value determined for (J 'P can be assessed as follows. For cp = 0° and as measured from a surface parallel to the over rolling track, it follows from Eq. 7 and Fig lOa that
(8) Similarly, as measured from a section perpendicular to the rolling track (now the circumferential direction is perpendicular to the occurring surface; then the roles of circumferential and radial components of stress are reversed in Eq. 7, it follows (cf. Fig. lOb) that
The introduction of the slots for the cross section shown in Fig. lOb, running through the elastically and into the plastically deformed region (cf. Section 2.2), will lead to relaxation of the macrostress (J 1-,r I pertaining to the whole body. Then it follows from the measured values of stress (Fig. lOb) that
II II ° MP (J1-,r -(J//,c ~ a (10) and thus:
2.4. Microstresses The hardened steel possesses large microstrains and consequently broad diffraction lines appear in the diffractogram. Two {211} a-Fe diffraction lines are shown in Fig. lla. These profiles were recorded from tangential inner ring specimen (see Fig. 6) in an advanced stage offatigue. The width of the {211 } a-Fe diffraction profile obtained for the center of the altered
region can be compared with the as measured profile obtained for a location, away from the center location, in the unaltered microstructure. Hence, microstructural changes (metal softening) in the subsurface region of fatigue tested bearings lead to a change (reduction) in diffraction-line broadening [8].
