The effects of machined topography on fatigue life of a nickel based superalloy

The surface topography of engineering components is known to affect fatigue behaviour. However, defining topography based on the average roughness (Ra) parameter is considered to be inadequate when correlating to fatigue performance. Alternative correlations utilising areal topographic parameters would therefore be valuable. This has been addressed through areal topographic measurements and fatigue testing of an advanced nickel based superalloy, Alloy720Li. Low cycle and high cycle … Continue reading The effects of machined topography on fatigue life of a nickel based superalloy

A quantitative approach to study the effect of local texture and heterogeneous plastic strain on the deformation micromechanism in RR1000 nickel-based superalloy

In a weakly textured material with relatively pore-free and homogeneous microstructure, the local texture can influence primary crack propagation and secondary crack initiation, depending on specific microtexture cluster size. Moreover, the plastic strain assessment and strain quantity within individual grains are essential for understanding the material susceptibility to crack initiation and propagation at various loading conditions and temperature ranges. In the current study, electron backscatter … Continue reading A quantitative approach to study the effect of local texture and heterogeneous plastic strain on the deformation micromechanism in RR1000 nickel-based superalloy

Elevated Temperature Creep Deformation of a Single Crystal Superalloy through the Small Punch Creep Method

Small punch testing is now a widely recognised approach for obtaining useful mechanical property information of critical structural components, particularly in the nuclear industry. However, to date the utilisation of this method has been limited to isotropic materials such as aluminium alloys and steels.This paper will look to utilise the small punch(SP) test to assess the creep response of 〈001〉-orientated CMSX-4 at temperatures above 950°C. An orthogonal rafting … Continue reading Elevated Temperature Creep Deformation of a Single Crystal Superalloy through the Small Punch Creep Method

Creep Lifing Methodologies applied to a single crystal superalloy by use of small scale test techniques

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 techniquesprove 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 … Continue reading Creep Lifing Methodologies applied to a single crystal superalloy by use of small scale test techniques

Crack Growth of a Polycrystalline Nickel Alloy under TMF Loading

Thermo-mechanical fatigue (TMF) is an important factor for consideration when designing aero engine components due to recent gas turbine development, thus understanding failure mechanisms through crack growth testing is imperative. In the current work, a TMF crack growth testing method has been developed utilising induction heating and direct current potential drop techniques for polycrystalline nickel-based superalloys, such as RR1000. Results have shown that in-phase (IP) testing produces accelerated crack growth … Continue reading Crack Growth of a Polycrystalline Nickel Alloy under TMF Loading

Development of true-stress creep model through analysis of constant-load creep data with application to finite element methods

The creep behaviour of the nickel-superalloy RR1000 is studied through a number of constant-load creep tests. It is often assumed that creep data generated by constant-load testing are unsuitable for building a generalised creep model due to the non-constant stresses incurred. Analysis of existing models shows that significant errors may occur in many approaches, which attempt to recreate the strain evolution with time. A model … Continue reading Development of true-stress creep model through analysis of constant-load creep data with application to finite element methods

The Non-Proportional Behaviour of a Nickel-Based Superalloy at Room Temperature, and Characterisation of the Additional Hardening Response by a Modified Cyclic Hardening Curve

A study was carried out where tension-torsion deformation strain-controlled tests were completed at Swansea University, to characterise the non-proportional hardening response of a nickel-based superalloy across a range of strain ranges. The data generated was used to assess the validity of a non-proportional cyclic hardening curve correction proposed by Socie and Marquis to represent the material’s hardening response. This modification involves the linear translation of … Continue reading The Non-Proportional Behaviour of a Nickel-Based Superalloy at Room Temperature, and Characterisation of the Additional Hardening Response by a Modified Cyclic Hardening Curve