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Abstract

Creep tests have been carried out at 750°C on sheet specimens of Nimonic 90 having thicknesses between 0·15 and 1·7mm and grain sizes in the range 0·04−0·07 mm, but mostly ∼0·05 mm. The results show that there is a significant decrease in creep performance when the thickness is less than about 1mm and that failure occurs as a result of grain-boundary cavitation, irrespective of section size. For specimen thicknesses of 0·28 and 1·7mm the stress dependence of the minimum creep rate was similar to that expected for bulk material, suggesting that diffusion creep was not responsible for the decrease in creep resistance of the thinner specimens. A simple mechanism is proposed to explain the effect of section size on life to rupture and the implications of the interpretation are discussed from the point of view of the practical applications of thin sections in turbine components.

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References

OXX

G. D.

: Int. Conf. on Creep and Fatigue, Philadelphia, 1973, Institution of Mechanical Engineers.

RICHARDS

E. G.

: J. Inst. Met., 1968, 96, 365–370.

WINSTONE

M. R.

: ‘Creep properties of unidirectionally solidified thin section coatings‘, NGTE Report No. NT 1013, June 1976.

WHITEENBERGER

J. D.

: Metall. Trans., 1976, 7A, 611–619.

BETPERIDGE

and RESLOP

: ‘The Nimonic alloys‘, 232; 1974, London, Edward Arnold.

MATLOCK

D. K.

and NIX

W. D.

: Metall. Trans., 1974, 5, 1401–1412.

BFITERIDGE

and HESLOT

: ‘The Nimonic alloys‘, 100; 1974, London, Edwatd Arnold.

GIBBONS

T. B.

and HOPKINS

B. E.

: Met. Sci. J., 1971, 5, 233–240.

Creep properties of Nimonic 90 in thin section

Abstract

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References