Creep and fracture in high-temperature components—Design and life assessment issues

Characterisation of microstructure and creep properties of alloy 617 for high-temperature applications

“…Forecasted requirements for USC applications have set the targets at minimum creep strength of 100 MPa at 100000 h of service [1][2][3][4][5][6][7]. Since the microstructure of most of the candidate nickel base alloys has not been investigated after such long exposure periods of time, modelling activity has proven to be helpful in predicting the material microstructural response under simulated service conditions [8]. The superior combination of high temperature strength, corrosion/oxidation resistance and creep resistance make alloy INCONEL 617 (referred to as alloy 617) one of the Ni-base candidate materials.…”

Development and Assessment of a New Empirical Model for Predicting Full Creep Curves

“…Numerically defining the fit of a function is a complex problem as there are many ways of doing so requiring a balance between quantitative and qualitative errors [ 8 , 9 , 10 ]. The Z parameter currently recommended by the ECCC, is given as Z = 10 2.5S where S is the standard deviation of the residual log time [ 11 ]. This measure gives a quantitative approach on a logarithm scale which does not necessarily reflect the nature and magnitude of the whole curve, and does not provide as clear a comparison to select acceptability criteria.…”

A review of non-destructive techniques for the detection of creep damage in power plant steels

“…It is commonly assumed that voids can be detected at a relatively early stage of creep [9], and indeed Cr-Mo welds with modest levels of cavity concentration have been in service for several years without subsequent failures [29,30]; however, some studies have reported that, in the same materials, cavities may be detectable on the surface only shortly before fracture [31][32][33][34]. It has also been observed that the number of cavities per unit area, which is often used in practice as a parameter indicative of the level of creep damage, may apparently decrease as rupture is approached, because cavities start to link up to form microcracks: this may lead to erroneous assessments [11], but the presence of cracks would usually be interpreted as a more advanced damage state and therefore the component would be repaired or replaced.…”