Improvement of fatigue behavior of mechanically surface treated materials by annealing
- Univ. Gh Kassel (Germany). Inst. of Materials Technology
The positive effects of mechanical surface optimization methods for fatigue lifetime and strength are generally attributed to the formation of compressive residual stresses and strain hardening in near surface layers. This work concentrates on the cyclic deformation behavior of three different commercial, widely used alloys (steels SAE 1045 and AISI 304, magnesium wrought alloy AZ31) subjected to thermal treatment after mechanical surface optimization. In the case of SAE 1045 fatigue lifetime as well as fatigue endurance strength were shown to be affected positively by different heat treatments in spite of residual macro and micro stress relaxation. Macroscopically according to Manson-Coffin`s law this improvement can be explained by the reduction of plastic strain amplitude. Microscopically, strain ageing can be identified as the responsible process. For all three materials, optimum heat treatment temperatures and times are suggested, derived from hysteresis measurements and cyclic lifetimes. Finally, it will be shown that further surface optimization can be achieved by simultaneously applying mechanical and thermal treatments (thermomechanical rolling or peening).
- OSTI ID:
- 691362
- Journal Information:
- Scripta Materialia, Vol. 41, Issue 8; Other Information: PBD: 10 Sep 1999
- Country of Publication:
- United States
- Language:
- English
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