A multi-level model for the analysis and prediction of creep and creep fracture of 2.25Cr–1Mo steel tubes

The creep and creep rupture properties of 2.25Cr–1Mo steel tubes have been analysed using the Wilshire equations. The observed behaviour patterns are then discussed in terms of the dislocation processes governing creep strain accumulation. A suitable statistical framework for analysing both the single and multi batch data available on this material is then specified. It is shown that ignoring the hierarchical nature present in many … Continue reading A multi-level model for the analysis and prediction of creep and creep fracture of 2.25Cr–1Mo steel tubes

A Novel Approach to the Prediction of Long-Term Creep Fracture, with Application to 18Cr-12Ni-Mo Steel (Bar, Plate, and Tube)

Designers of new power-generation plants are looking to make use of new and existing high-strength austenitic steels so that these plants can operate with much higher steam and, therefore, metal temperatures. However, this article shows that the Wilshire–Scharning methodology is incapable of producing accurate long-term-life predictions of these materials from short-term data. This article puts forward a modification of this approach that should enable existing … Continue reading A Novel Approach to the Prediction of Long-Term Creep Fracture, with Application to 18Cr-12Ni-Mo Steel (Bar, Plate, and Tube)

A generalisation of the Wilshire–Scharning methodology to creep life prediction with application to 1Cr–1Mo–0.25 V rotor steel

Wilshire–Scharning have recently developed a new methodology that has been demonstrated to deliver accurate longer term creep life predictions, and so offers the prospect of cost-effective acquisition of long-term creep design data. This methodology differs from existing approaches to creep life prediction by normalising the applied stress through the appropriate tensile strength. This article develops a generalisation of this Wilshire–Scharning model that has the potential … Continue reading A generalisation of the Wilshire–Scharning methodology to creep life prediction with application to 1Cr–1Mo–0.25 V rotor steel

Use of partial least squares for identifying the effect of through process variables on some of the magnetic properties (permeability) of grain oriented electrical steel

As there are a large number of process variables involved in manufacturing grain oriented electrical steel, partial least squares (PLS) was used to study the influence of these process parameters on some magnetic properties and in particular on permeability. It was found that a model containing just two PLS components provided an adequate best fit to the process data with the most important variables being … Continue reading Use of partial least squares for identifying the effect of through process variables on some of the magnetic properties (permeability) of grain oriented electrical steel

An alternative approach to estimating the parameters of a generalised Grey Verhulst model: An application to steel intensity of use in the UK

Being able to forecast time series accurately has been quite a popular subject for researchers both in the past and at present. However, researchers have resorted to various forecasting models that have different mathematical backgrounds, such as statistical time series models, causal econometric models, artificial neural networks, fuzzy predictors, evolutionary and genetic algorithms. In this paper, a brief review of a relatively new approach, known … Continue reading An alternative approach to estimating the parameters of a generalised Grey Verhulst model: An application to steel intensity of use in the UK

Development of a high temperature flow stress model for AerMet 100 covering several orders of magnitude of strain rate

Constant strain rate, constant velocity and Hopkinson Pressure Bar compression tests were carried out on AerMet 100 martensitic steel between 1130 °C and 1250 °C spanning strain rates from 0.01 s−1 to 4000 s−1. The results were used to generate a predictive flow stress model over the entire range of test conditions. The effect of initial austenite grain size on flow stress was found to follow the Hall–Petch relationship. … Continue reading Development of a high temperature flow stress model for AerMet 100 covering several orders of magnitude of strain rate

Insights into microstructural interfaces in aerospace alloys characterised by atom probe tomography

Atom probe tomography (APT) is becoming increasingly applied to understand the relationship between the structure and composition of new alloys at the micro- and nanoscale and their physical properties. Here, we use APT datasets from two modern aerospace alloys to highlight the detailed information available from APT analysis, along with potential pitfalls that can affect data interpretation. The interface between two phases in a Ti–6Al–4V … Continue reading Insights into microstructural interfaces in aerospace alloys characterised by atom probe tomography

Prediction of fatigue lives at stress raising features in a high strength steel

The fatigue properties of the high strength stainless steel CSS42L have been evaluated under strain and stress controlled conditions. The results have been used to derive a predictive approach based on the Walker strain equation. Accurate predictions are obtained for VCN and DEN specimens although the lower stress concentration RCN specimen is shown to compare more readily with plain specimen stress controlled data. The difference in fatigue life between … Continue reading Prediction of fatigue lives at stress raising features in a high strength steel

The changing constants of creep: A letter on region splitting in creep lifing

This letter explores the issues surrounding the use of region splitting as a means to improve current creep lifing techniques.  The history of the technique is discussed briefly and its current implementation by major research groups discussed in more detail.  An example of novel or non-traditional region splitting is also explored with its first known application to nano-creep.  The issues surrounding region splitting when considered … Continue reading The changing constants of creep: A letter on region splitting in creep lifing

Prediction of fatigue lives at stress raising features in a high strength steel

The fatigue properties of the high strength stainless steel CSS42L have been evaluated under strain and stress controlled conditions. The results have been used to derive a predictive approach based on the Walker strain equation. Accurate predictions are obtained for VCN and DEN specimens although the lower stress concentration RCN specimen is shown to compare more readily with plain specimen stress controlled data. The difference in fatigue life between … Continue reading Prediction of fatigue lives at stress raising features in a high strength steel