Creep lifing methodologies applied to a single crystal superalloy by use of small scale test techniques

Abstract

In recent years, advances in creep data interpretation have been achieved either by modified Monkman-Grant relationships or through the more contemporary Wilshire equations, which offer the opportunity of predicting long term behaviour extrapolated from short term results. Long term lifing techniques prove extremely useful in creep dominated applications, such as in the power generation industry and in particular nuclear where large static loads are applied, equally a reduction in lead time for new alloy implementation within the industry is critical. The latter requirement brings about the utilisation of the small punch (SP) creep test, a widely recognised approach for obtaining useful mechanical property information from limited material volumes, as is typically the case with novel alloy development and for any in-situ mechanical testing that may be required. The ability to correlate SP creep results with uniaxial data is vital when considering the benefits of the technique. As such an equation has been developed, known as the kSP method, which has been proven to be an effective tool across several material systems. The current work now explores the application of the aforementioned empirical approaches to correlate small punch creep data obtained on a single crystal superalloy over a range of elevated temperatures. Finite element modelling through ABAQUS software based on the uniaxial creep data has also been implemented to characterise the SP deformation and help corroborate the experimental results.

Application of the small punch test to determine the fatigue properties of additive manufactured aerospace alloys

“…To date these methods have largely been adopted to characterise the creep [3], [4], tensile [5], [6] and fracture characteristics [7], [8] of numerous material systems [9], [10] from a range of industrial applications for sampling [11], [12]. This paper will now detail the research undertaken in realising a small-scale test methodology capable of characterising the localised fatigue properties of ALM built structures.…”

Fracture toughness characterization through notched small punch test specimens

“…Its main attribute resides in the very small specimens employed (generally 8 mm diameter and 0.5 mm thickness), such that it may be considered a non-destructive experiment. The SPT has consistently proven to be a reliable tool for estimating the mechanical [4,5] and creep [6,7] properties of metallic materials, as well as its environmentally-assisted degradation [8]. However, its capabilities in fracture toughness characteriza-tion are still a controversial subject.…”

Two different small size testing technique for the creep residual life evaluation of an equiaxed Ni-based superalloy for GT blade and vane application

“…1,4,[7][8][9]20,22,23 However, the few curves available for high-strength materials 19 and for CMSX-4 24,25 indicated similar values to what was experienced by the small punch creep test on René 80. This behaviour was judged to be due to the low ductility and high strength of the tested material.…”