SEDL / STP / STP515-EB / STP34678S

The Evaluation of Creep Damage in a Cr-Mo-V Steel

Goldhoff, RM
Manager, Applied Research and research metallurgist, Materials and Processes Laboratory, General Electric Co., Schenectady, N. Y.

Woodford, DA
Manager, Applied Research and research metallurgist, Materials and Processes Laboratory, General Electric Co., Schenectady, N. Y.

Pages: 18    Published: Jan 1972

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Abstract

An attempt has been made to determine and quantify the accumulation of creep damage in Cr-Mo-V steel. Damage is defined in terms of post exposure rupture data and hardness measurements which are shown to be interrelated. Correlation between the post exposure rupture life and the initial exposure parameters are achieved by simple parametric techniques which then form the basis for graphical representation of damage accumulation as a function of exposure time, stress, and temperature.

The way in which these curves may be used to predict failure under nonsteady conditions of stress and temperature is described. In general the linear life fraction cumulative damage rule is unrealistic for this material, although under certain restricted conditions it may give a reasonable prediction of life. Apart from the measured nonlinearity with time of damage accumulation, the present results confirm that the common assumption of a unique failure criterion independent of the test conditions cannot be justified.