Richard Clegg

A fluid flow based model to predict liquid metal induced embrittlement crack propagation rates

Abstract An analytical model is developed for the rate of supply of embrittler to the crack tip in liquid metal induced embrittlement (LMIE), assuming that crack propagation rate is controlled by viscous losses in the liquid metal. The results of the modelling are compared with experimentally determined data for crack propagation rates in LMIE. This study indicates that in several systems the LMIE crack propagation rate is not controlled by viscous losses in the crack and that a study of crack propagation rates in LMIE may yield useful insight into the micromechanisms of LMIE fracture.

Liquid metal embrittlement of tensile specimens of En19 steel by tin

Abstract Liquid metal induced embrittlement (LMIE) of En19 steel was investigated by tensile testing specimens coated with liquid pure tin. Testing was carried out over a range of steel hardnesses and test temperatures, and for each material hardness the temperature above which recovery of the unembrittled tensile behaviour of the specimens occurred was measured. Metallographic examination of each of the specimens was carried out and the results of this examination were compared with the mechanical behaviour. This work illustrates the importance of dissolution of the steel by tin on the behaviour of the specimens tested at the higher temperatures.

Failure of planetary pinions in earth moving equipment - A failure analysis approach

A series of failures of planetary pinions occurred in the final drive epicyclic gearbox of large trucks used in underground mining. A metallurgical analysis indicated that failure had occurred by internal rupture of the gear. This was attributed to poor heat treatment procedures used in case hardening the gear. This had induced high residual stresses just below the case/core interface, leading to the internal rupture of the gear.

Production of Si+ and Cl+ ion beams from a Freeman type ion source using low toxicity and non-corrosive vapours as source gas

Abstract A method is proposed for production of Si+ and Cl+ ions in Freeman type ion sources using low toxicity and non-corrosive vapours of hexamethyldisilane ((CH3)3SiSi(CH3)3) and carbon tetrachloride (CCl4), respectively. These source materials can be used without expensive and complicated safety systems required for silane and chlorine source gases. Experimental X-ray photoelectron spectroscopy results show that in the case of (CH3)3SiSi(CH3)3 vapour used as the ion source gas, the ion beam, after using standard magnetic field ion mass analysis for mass 28, contains about 62% of 28Si+ ions. It is assumed that the molecular ions C2H4+ with the same mass 28 are the main component of the remaining 38% of this ion beam. In the case of the use of CCl4 vapour as ion source gas and magnetic field mass analysis set for mass 35, a pure Cl+ beam is observed; there are no other ions of mass 35 that can be formed from the source gas. The same system when used with water vapour as a source gas can produce pure ion beams of O+ and/or H+ ions without adverse effects produced in the ion source by oxygen gas (oxidation) or typical safety problems with a hydrogen gas supply (explosive).

Numerical Investigation of Hammer Erosive Wear due to Particle Impact

Hammers are the key machine element of high-speed hammer mills which lead to the coal pulverisation process. Progressive material loss from the hammer occurs due to the mechanical interactions between the coal particles and the hammer surface. Coal pulveriser industries implement extensive efforts to combat against premature material loss from the hammer surface due to coal particle impact which may result in premature failure. This work investigates the erosion wear mechanism through computational simulation. A numerical model is developed using Abaqus® to simulate the solid coal particle impacting onto the hammer (target).The Abaqus/Explicit® dynamic simulation solver is used for this analysis. The interactions between the solid coal particles and the target are modelled using the Abaqus/Explicit® element deletion method. The Johnson and Cook plasticity model is employed to analyse the flow stress behaviour of ductile materials during impact. The developed stress and plastic strain are analysed through simulation on the impact surface. This model is applied to different ductile alloys to determine the best erosion wear resistance hammer material for extending the operating life of hammers in the coal pulverisation process.

The Sixth International Conference on Engineering Failure Analysis - Part 2

The first Special Issue of the Fourth International Conference on Engineering Failure Analysis (ICEFA-4) contains a number of selected papers presented at the conference that was held on the 4–7th July 2010 at Churchill College, Cambridge, UK. Sponsored by Elsevier Science and Engineering Failure Analysis, the Conference brought together leading workers in the field of failure analysis, structural integrity and related studies, with delegates attending from around the world. Topics covered in the conference programme covered a wide range of issues in the arena of Engineering Failure Analysis, in addition to considering the legal and ethical obligations of those working in the field. With six keynote presentations, eighty-eight oral and one hundred and six poster presentations embracing a wide range of failure mechanisms and industrial applications, attendance was a record for the ICEFA series to date.