SEDL / STP / STP1159-EB / STP25835S

Improving Fretting Fatigue Strength at Elevated Temperatures by Shot Peening in Steam Turbine Steel

Mutoh, Y
Professor and research associate, Nagaoka University of Technology, Nagaoka-shi,

Satoh, T
Professor and research associate, Nagaoka University of Technology, Nagaoka-shi,

Tsunoda, E
Toshiba Corporation, Yokohama,

Pages: 11    Published: Jan 1992

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Abstract

Fretting fatigue tests at elevated temperature were carried out using shot-peened specimens to improve the high temperature fretting fatigue strength of 12Cr-Mo-W-V steam turbine steel. Shot peening improved fretting fatigue strengths by a factor of 1.8 at an elevated temperature (773 K) as well as at room temperature. Residual compressive stresses first drop rapidly by a factor of three and then level off. Residual compressive stresses of 200 MPa were measured after a 30 000 h exposure at 773 K. Shot peening is thus shown to be effective over long periods at 773 K.