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Conclusions 1.The magnitude of the residual stresses and their sign and distribution across the section of carburized plus quenched specimens depend on the case depth and steel composition.2.As the case depth increases from 0. 6 to 2. Z mm (0. 024 to 0. 087 in), the surface residual stresses change systematically. With a relatively shallow case, there are surface compressive stresses which increase until the case depth has reached 1.2 mm (0.047 in). With still heavier cases, they start to decrease and when the depth reaches 2 mm, they change to tensile stresses.3.Corresponding to the change in surface residual stresses, there is a change in the magnitude and character of the stresses through the section of case carburized specimens. When the case depth does not exceed 1.2 mm, the residual stresses within the section change smoothly. When the depth is above 2 mm there is a sharp drop of the compressive stresses.4.The magnitude and sign of the residual stresses is greatly affected by the presence of excess carbides and retained austenite in the case.

1.A study of the mechanical properties of steel 30KhGS showed that repeated impact loads bring out peculiarities which cannot be observed in static tests and in tests involving single bending impacts.2.The curve for impact fatigue strength of this steel as function of the tempering temperature shows two maxima: one at 200°C and the other at 400°C. The magnitude of these maxima is determined by the single-blow energy.