Dresden 2006 – wissenschaftliches Programm

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MM: Metall- und Materialphysik

MM 25: Poster Session

MM 25.6: Poster

Mittwoch, 29. März 2006, 15:30–17:30, P4

Effect of Grinding Deformation on the Reheating Behavior of Steels — •Jürgen Gegner — SKF GmbH, Material Physics, Ernst-Sachs-Str. 5, D-97424 Schweinfurt, Germany

In the production of machine elements, after soft forming and heat treating processes hard surface finishing represents the final manufacturing step. Besides dimensional shaping, its main goal is the fabrication of functional areas with low roughness for good wear resistance. Additionally, crack-inhibiting compressive residual stresses are formed near the surface. During grinding of hardened steel, a narrow edge zone of about 0.01 mm in thickness experiences strong plastic deformation. Mechanical residual stresses up to 600 MPa in compression are built up. Although the dislocation density rises, the martensite {211} line broadening decreases by around 0.2^∘ because of the formation of more stable defect structures like multipoles. Recently, post-machining thermal treatment of such steel parts below the tempering temperature was proposed to extend service lifetime of bearings or cogwheels [1]. It is shown for martensitic and banitic hardening that the pronounced reduction in XRD half width corroborates this recommendation. A model is established, which explains the effect by dislocational segregation of carbon and carbide dissolution. [1] J. Gegner: German Patent No. DE 102 09 264 B4 (2005)