Abstract
Creep tests were carried out on notched plate specimens of nickel-based superalloy GH4169 with different stress concentration coefficients. It was found that the duration of the first stage of the creep curve increases with the increase of stress concentration coefficient, while the fracture ductility decreases with the increase of stress concentration coefficient. To predict the life of notched plate specimens, four constitutive models were used to analyze the stress and strain of the notches. It was found that the average Von Mises equivalent stress (AVES) on the minimum notch section first decreases and then increases with the creep time, resulting in a minimum value. The minimum average Von Mises equivalent stress (MAVES) is considered as the characteristic stress of notched specimens in this paper. The creep life equation is fitted according to the results of creep tests of smooth specimens, and then the predicted life of notched specimens is obtained by substituting the minimum average Von Mises equivalent stress of notched specimens into the creep equation. The prediction results of the four constitutive models are within 2 times the dispersion band, and the three-stage model is within the 1.5 times dispersion band.
Highlights
This paper proposes a new method for predicting rupture life based on AVESes, without using the concept of critical rupture ductility
With the increase of notch stress concentration coefficient, the difference of the MAVES calculated by different constitutive models gradually increases
The and life prediction method are selected, the stress rupture life prediction results of higher accuracy model of prediction results maybe because the calculation results of the three-stage the notched specimens are almost within the double dispersion band
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The commonly used methods include the skeletal point method [1,2,3,4,5,6], the multi-axial ductility exhaustion method [7,8,9,10,11], and the prediction method based on AVES [12]. These methods cannot be operated without the finite element analysis of notched specimens. The influence of four different creep constitutive equations and three different creep life equations on the life prediction is analyzed in this paper
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