Hardfacing using supersonic laser depostion of stellite-6

The capability of manufacturing coatings is of central importance in engineering design. Many components require nowadays the application of additional layers, to enhance mechanical properties and protect against hostile environments. Supersonic Laser Deposition (SLD) is a novel coating method, based upon Cold Spray (CS) principles. In this technique the deposition velocities can be significantly lower than those required for effective bonding in CS applications. The addition of laser heat energy permits a change in the thermodynamic experience of impacting particles, thereby offering a greater opportunity for metallurgical bonding at lower velocities compared to the CS process technology. The work reported in this paper demonstrates the ability of the SLD process to deliver hard facing materials to engineering surfaces. Stellite-6 has been deposited on low carbon steel tubes over a range of process parameters, determining the appropriate target power and traverse speeds for coating deposition. Coating properties and parameters were examined to determine the main properties, micro-structure and processing cost. Their morphology was studied through optical microscopy, SEM and X-Ray Diffraction. The results have shown that SLD is capable of depositing Stellite-6, with enhanced properties compared to laser clad counterparts.

Explosion pressure prediction via polynomial mathematical correlation based on advanced CFD Modelling

Computational Fluid Dynamics CFD can be used as a powerful tool supporting engineers throughout the steps of the design. The combination of CFD with response surface methodology can play an important role in such cases. During the conceptual engineering design phase, a quick response is always a matter of urgency. During this phase even a sketch of the geometrical model is rare. Therefore, the utilisation of typical response surface developed for congested and confined environment rather than CFD can be an important tool to help the decision making process, when the geometrical model is not available, provided that similarities can be considered when taking into account the characteristic of the geometry in which the response surface was developed. The present work investigates how three different types of response surfaces behave when predicting overpressure in accidental scenarios based on CFD input. First order, partial second order and complete second order polynomial expressions are investigated. The predicted results are compared with CFD findings for a classical offshore experiment conducted by British Gas on behalf of Mobil and good agreement is observed for higher order response surfaces. The higher order response surface calculations are also compared with CFD calculations for a typical offshore module and good agreement is also observed. © 2011 Elsevier Ltd.