Residual stress profiles in speed gears for automotive vehicles were determined. The profiles were measured at the root between two teeth of the gears by x-ray diffraction. The gears were cemented, quenched and annealed. After these heat treatments, compressive residual stresses were introduced by shot-peening. The profiles of stress distribution indicate the maximum of compressive residual stress (-950 MPa) at a depth of 0.05 mm. The stresses decrease to zero at a depth of 0.25 mm. In the gears without shot-peening the maximum of compressive residual stress (-600 MPa) is on the surface and decrease to zero at a depth of 0.30 mm.
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