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November 1981 - present
Publications
Publications (135)
White Etching Areas observed in failed rolling bearings have been associated with the presence of Severe Plastic Deformation conditions, which can be achieved by High-Pressure Torsion tests; thus, this technique was selected to produce White Etching Structures in annealed AISI 52100. Their origin arises from two main phenomena: Firstly, the relativ...
The rapid adoption of the advantageous PEEK and its composites paired with steel counterparts in many tribological applications has prompted intense research to investigate their tribological properties under lubrication.
This study investigated the effect of oil-lubrication and proposed a mechanism of action. Compared to the dry conditions, oil-lu...
While it is well known that during RCF tests the formation of nascent catalytic sites on the wear track can break down hydrocarbon molecules to release atomic hydrogen, the potential of the hydrogen environment in fuel cells to hydrocrack the hydrocarbon lubricant in high pressure rolling contacts has so far been ignored. Here we investigate for th...
Poly-Ether-Ether-Ketone (PEEK) has been widely used for tribological applications with steel counterparts because of its superior mechanical and self-lubricating properties. Lubrication has the potential to further improve its performance. However, lubrication can have positive or negative effects depending on the operating conditions and little is...
Weld toe fatigue crack initiation is highly dependent on the local weld toe stress-concentrating geometry including any inherent flaws. These flaws are responsible for premature fatigue crack initiation (FCI) and must be minimised to maximise the fatigue life of a welded joint. In this work, a data-rich methodology has been developed to capture the...
In this study, stainless steel and titanium (Ti) tubes obtained from a turbofan engine after the end of its lifetime were analyzed in order to compare the amount of pyrolytic coke present and its influence on the parent, base material. Various analytical techniques including microhardness and topographical evaluations, optical emission spectrometry...
The problem of indentation of ductile materials by ball indenters is, in this paper, addressed by numerical modelling. A finite element model is built using general purpose software. The axisymmetry of the problem is taken into account thus reducing its dimensionality. Particular attention is given to contact modelling as well as mesh design for op...
An improved elasto-plastic characterisation technique relying on instrumented indentation data, accounting for frame compliance, spherical indenter imperfections and, most importantly, material pile-up at indentation edges was validated on experimental data from control specimens with known properties. The method was subsequently applied to the cha...
The chemical interactions between the kerosene compounds and the stainless steel structure of the tubular components, through which kerosene is transported, develop a degradation phenomenon, causing intergranular contamination from the surface to the inner part (process based also on mass transport, i.e. diffusion at low temperatures). This is the...
White structure flaking (WSF) has been found to be one of the failure modes in bearing
steels under rolling contacts through the formation of cracks associated with a microstructural change
called white etching area (WEA). In the present research, the effects of the high-pressure torsion
(HPT) process on the microstructure and mechanical properties...
The limitations of 2-dimensional electrodes can be overcome by using three-dimensional materials having sufficient porosity and active area while offering moderate mass transport rates and a relatively low pressure drop at controlled electrolyte flow rate. In concept, a wide variety of metal, ceramic and composite materials are possible but restric...
Atmospheric plasma spraying is used here to obtain titanium sub-oxide coatings on the following electrode substrates: a 316 stainless steel sheet, an aluminium alloy 2024 sheet, a carbon–polymer composite and nickel foam. It is necessary to increase the roughness of the substrate to aid the adhesion of the coating to the smooth electrodes; this is...
Serial mechanical sectioning and high resolution X-ray tomography have been used to study the three-dimensional morphology of small fatigue cracks growing in a 12 Cr tempered martensitic steam turbine blade material. A range of surface conditions has been studied, namely polished and shot peened (with varying levels of intensity). In the polished (...
Improved high conductivity titanium sub-oxide coated electrodes
obtained by Atmospheric Plasma Spray”
M.Robotti,S.Dosta,M.Gardon, B.Mellor,R.Wills, I.G Cano, J.M.Guilemany
Proceedings EUROMAT 2015. Federation of European Societies (FEMS).Symposium E1 - Materials for energy.Warsaw.Poland. (2015).
The mechanism of grain refinement in Cu-doped Ni–Ti thin films has been investigated by transmission electron microscopy. Sputter-deposited (Ni,Cu)-rich Ni–Ti–Cu thin films exhibited a columnar structure consisting of grains whose lateral size decreased with increasing Cu content. Cu-rich grain boundary segregation was found to become prominent in...
Replacing Electrodes in a Real Battery by Means of Highly-Efficient Atmospheric Plasma Spray Titanium Sub-Oxide Coatings
M. Gardon, S. Dosta, J.M.Guilemany, M. Kourasi, B. Mellor, R. Wills
Proceedings International Thermal Spray Conference and Exhibition.
ITSC 2014. CD ROM.Ref 3767. ASM International & DVS. Thermal Spray Society. Barcelona.Spain....
This study investigates the performance of particulate-filled thermoplastic fluoropolymer coatings under both dynamic impact tests and static indentation tests. An instrumented impact testing rig was used to measure the impact energy, impact velocity, acceleration and impact force during the impact tests. Coating samples with different thicknesses...
The plastic deformation resulting from shot peening treatments applied to the ferritic heat resistant steel FV448 has been investigated. Two important effects have been quantified: surface roughness and strain hardening. 2D and 3D tactile and optical techniques for determining surface roughness amplitude parameters have been investigated; it was fo...
The effect of shot peening on subsequent low cycle fatigue behaviour of a representative low pressure steam turbine blade material has been investigated in bend test samples. An analysis of the short fatigue crack growth behaviour has been conducted. For samples with no stress concentration feature, shot peening was found to have a more evident ben...
Shot peening is a well known process applied to components in order to improve their fatigue
resistance. In recent years, there has been an increasing interest in including the effects of the
shot peening process in life assessment models since this would allow a reduction in
conservatism compared to those in current application. Part 1 of this rev...
NiTi shape memory alloys are known to exhibit unusual properties such as shape memory effect and superelasticity even at the micro- and nano-scales, thus making them particularly attractive materials for micro-electro-mechanical systems (MEMS). In addition to the field of application mentioned above, being thermoelastic martensitic transformation a...
Interest in multifunctional structures made automatically from multiple materials poses a challenge for today's additive manufacturing (AM) technologies; however the ability to process multiple materials is a fundamental advantage to some AM technologies. The capability to fabricate multiple material parts can improve AM technologies by either opti...
The indentation response of a pseudoelastic nickel-titanium based shape memory alloy (SMA) has been analyzed. Indentation tests have been carried out at room temperature using a spherical diamond tip and indentation loads in the range 50-500 mN in order to promote a large stress-induced transformation zone in the indentation region and, consequentl...
Four point bend tests were conducted on two previously characterized particulate filled thermoplastic and thermoset polymeric coatings, the acoustic emission (AE) method being utilized to monitor the damage progress during the tests. Different damage mechanisms operating in the polymeric coatings can be recognized by the different amplitude range o...
The improvement in low cycle fatigue life created by shot peening ferritic heat resistant steel was investigated in components of varying geometries based on those found in conventional power station steam turbine blades. It was found that the shape of the component did not affect the efficacy of the shot peening process, which was found to be bene...
A two-dimensional finite element simulation of a welding process is developed for predicting temperature histories and residual stresses in a structural steel butt-welded joint. The purpose of the simulation presented in this paper is the assessment of the effect of uncertainties in thermal material, loading and constraint input on both the thermal...
This article presents a framework for integrating manufacturing knowledge within a design environment. An overview of past and present practice in the area of design and manufacturing collaboration is given. ‘Strangers’ are classified according to their degree of deviation from past designs. The method described makes use of non-conformance data in...
In this study, particulate filled thermoset polymeric coatings with two different coating thicknesses were subjected to four point bend loading while being monitored by acoustic emission in order to establish the failure modes of the filled polymeric coatings. The polymeric coatings were approximately 260μm and 350μm in thickness on a steel substra...
A ship building grade of carbon steel has been coated with copper by a furnace brazing process starting from a brass braze. An argon protective atmosphere was used to prevent oxidation of the steel. However, when the deposit was produced a low gas flow rate ensured that zinc was lost from the brass by oxidation leaving a copper deposit on the steel...
The effect of defects on the load-carrying behaviour of welded joint is investigated based on experimental and finite element studies on two types of fillet welded T-joints, one with various defects (referred to as T1) and the other of good quality (referred to as T2). Weld defects are examined through standard metallographic procedure. Material pr...
Pistons are commonly made from multicomponent Al–Si casting alloys, which have complex, interconnecting three-dimensional (3D) networks of secondary phase particles. They are non-serviceable parts and so must be able to withstand high cycle fatigue while operating at temperatures between 30 and 80% of T
m. Long fatigue crack growth tests were perfo...
Spatter results when droplets of liquid metal that have been ejected from the weld pool by the impact of small droplets from the covered electrode solidify and weld to the surface of the base material. The present paper studies spatter and reveals why these small droplets do not oxidise during their short trajectory and accounts for why they arrive...
In this work the authors have studied the phenomena in the interface of the coating made on soft carbon steel with electrodes with a high content of manganese. The study has been done with scanning electron microscope and X-rays mapping images. These images show how the alloy elements are distributed in each of the constituent elements presented in...
Microstructural features present at the interface between a weld deposited Stellite 6 hard facing and an austenitic stainless steel substrate are described. Elemental X-ray maps indicate that diffusion of carbon from the liquid Stellite to the austenitic stainless steel takes place along grain boundaries resulting in the formation of chromium carbi...
Fatigue initiation behaviour in three multi-component Al-Si casting alloys with varying Si content is compared using a range of microscopy and analytical techniques. A higher proportion of stiffer secondary phases leads to load transfer effects reducing particle cracking and particle/matrix debonding. Si appears stronger than the Al 9 FeNi phase, w...
As wear is a surface or near surface phenomenon it has long been realised that the wear resistance of a component can be improved by providing a surface of different composition from the bulk material. Although this book concentrates on surface coatings, the distinction between surface coatings and the process of modifying the surface by changing i...
Finite element simulations of spherical indentations accounting for frictional contact provide validated load–indentation output for assessing and improving existing methods used to determine the stress–strain curve of materials with significant pile-up. The importance of friction to the proper assessment of the pile-up effect is established. Weakn...
The stress distribution and fracture behaviour of soft soldered single and double lap joints have been studied. Stress analysis has been performed using transmission photoelasticity on plastic models. This allowed the shear stress distribution in the joint overlap to be determined. A fractographic study was also carried out on fractured joints made...
Surface Coatings for Protection Against Wear”, Edited by B.G.Mellor.
Chapter: “Thermal Spraying Methods for Protection Against Wear”
J.M.Guilemany, B.G.Mellor,J.Nin
Woodhead Publishing Limited. Abington, Cambridge. ISBN 1 85573 767 1.The nstitute of Materials, Minerals and Mining. 448p. London. UK. (2006).
Surface coatings for protection against...
The behaviour of a welded cruciform joint under quasi-static loads was simulated using the finite element method (FEM). The reliability of the FEM models was examined by solving a benchmark problem, carrying out a mesh sensitivity study and comparing the strain-moment relation with experimental measurements. Particular attention was given to the ac...
The microstructure of aluminium piston alloys comprises primary and eutectic silicon together with numerous intermetallics. Previous research has shown that primary silicon strongly influences both fatigue crack initiation and subsequent propagation behaviour, however, the detailed effects of varying silicon volume fraction and morphology have not...
The erosion wear performance of a thermally sprayed hard coating has been found to be inferior to that of sintered bulk material of the same composition. The anisotropic microstructure of thermally sprayed WC–Co–Cr coatings, in particular the low fracture toughness in a direction parallel to the substrate, i.e. parallel to the long side of the spla...
The theoretical stress trajectories (isostatics) for Mode I fracture are calculated. This is achieved by combining the general equations for isostatics and the expressions for the state of stress at a point under mode I loading. The trajectory is valid only in the elastic region at the tip of the crack and not in cases where plasticity exists. It w...
Suitable testing arrangements are made for assessing the strength of welded T-joint specimens and providing input for the validation of finite element simulations of their behaviour under load. Material characterisation across the various weld areas is carried out through tensile and hardness tests as well as standard metallographic procedures for...
The microstructure of aluminium piston alloys comprises primary and eutectic silicon together with numerous intermetallics. Previous research has shown that primary silicon strongly influences both fatigue crack initiation and subsequent propagation behaviour, however, the detailed effects of varying silicon volume fraction and morphology have not...
In recent years, adhesive joints have replaced numerous soldered joints, especially in applications where electrical conductivity is not required from the members of the joint. Nevertheless, soldered joints are still used in applications ranging from electronics to high-technology components. The present work seeks to demonstrate that soldered join...
Thermoset and thermoplastic polymeric materials are used as coatings on the bore of downhole tubulars such as water injectors in the oil industry. Previous work has indicated that such coatings can fail by impact damage and by abrasion from the wire used to lower inspection tools down the tubular. The wire is commonly called “slickline” and the typ...
Thermally sprayed coatings contain residual stresses that are produced in the spraying process. These may reduce the coating lifetime. In order to determine the optimum spraying conditions with respect to the residual stress level present, the acoustic emission (AE) during four-point bend tests on tungsten carbide–cobalt coatings sprayed onto mild...
A wavelet variance analysis procedure has been used for the characterisation of electrochemical noise measurements (ENM) made during corrosion of three grades of austenitic and superduplex stainless steels, with varying sulphur contents, when exposed to chloride media. The resulting electrochemical noise has been interpreted in terms of coupled cur...
Welding-induced residual stresses and distortion can play a very important role in the reliable design of welded joints and welded structures. However, general simple methods for the prediction of the distribution and magnitude of residual stresses are not available from the literature. A reliable and efficient numerical analysis of this complex ph...
Welding-induced residual stresses and distortion can play a very important role in the reliable design of welded joints and welded structures. However, general simple methods for the prediction of the distribution and magnitude of residual stresses are not available from the literature. A reliable and efficient numerical analysis of this complex ph...
Thermoplastic polymer matrix composites are used as coating materials for the bore of downhole tubulars used as water injectors in the oil industry. These coatings are primarily employed for corrosion resistance but must also resist mechanical damage from the inspection tools lowered at speed down the tubing. This mechanical damage is produced by t...
Mechanical damage of downhole tubing coatings through the impact of wireline tools is commonplace. This paper reports the results of laboratory "drop tube" impact tests on a range of commercially available coatings, the study being aimed at defining current coating limitations and directing future coating development work. In summarizing, work carr...
The formation of crevice corrosion on type 304L stainless steel when immersed in 0.05 M ferric chloride solution has been
used to investigate electrochemical potential noise measurements. The surface activity of the stainless steel was simultaneously
studied using a scanning electrode technique to provide corroborating evidence of crevice corrosion...
The behaviour of a welded cruciform joint under static loads was simulated using the finite element method (FEM). The geometry, material properties and loading conditions of the joint were identical to those of a specimen for which experimental results were available so that the FEM model could be validated. The effects of varying weld geometry and...
Over the last few years, material options for downhole tubing in water injection wells, particularly subsea wells where the cost of workover is prohibitive, have received considerable attention. A great deal of test and field experience demonstrates that the internal tubing coatings currently available do not have sufficient mechanical robustness t...
Electrochemical potential noise measurements have been used to investigate the initiation and development of crevice corrosion on type 304L stainless steel when immersed in a 0.05 M ferric chloride solution. The spontaneous potential noise fluctuations were recorded in a freely corroding system with respect to a Ag/AgC1 reference electrode. The sur...
The erosion performance and the interaction between the micro-mechanisms of erosion and the microstructure of a chemical vapour deposited boron carbide coating are presented. Samples were tested using both water–sand slurry and air–sand jet impingements at 90° incidence. Tests used angular quartz sand with a mean diameter between 135 and 235 μm and...
The ultimate strength of fillet welded joints is of vital importance when analysing the collapse behaviour of a welded structure. However, both the small size and difficulties in determining accurately, for the different regions of the weld, relevant material properties to input in a finite element analysis complicates modelling. Hence the strength...
The polymeric coatings on water injector tubing used in the offshore oil industry must resist corrosion from the injected water, but more importantly must resist mechanical damage from the inspection tools lowered at speed into the tubing. This mechanical damage is produced by the wearing action of the supporting wire against the coating (wireline...
The erosion performance and the interaction between the micro-mechanisms of erosion and the microstructure of a chemical vapour deposited boron carbide coating are presented. Samples were tested using both water–sand slurry and air–sand jet impingements at 90° incidence. Tests used angular quartz sand with a mean diameter between 135 and 235 ?m and...
The fracture toughness of two thermally sprayed tungsten carbide/cobalt–chromium coatings of nominally identically composition, 86WC–10Co–4Cr, one produced by the Detonation Gun (D-Gun) process and one by the High Velocity Oxy-fuel (HVOF) process, has been determined by the indentation method. Indentation testing revealed that both coatings exhibit...
Sand erosion studies of thermally sprayed WCCoCr (Denotation-Gun LW45) have been undertaken using a sand/water jet impingement rig. Results are presented which show that the erosion rate of sprayed compared to sintered tungsten carbide-cobalt-chrome is similar for low energy impacts but the sintered material outperforms by 4 times the sprayed mat...
Overlay welding is often used to produce a corrosion resistant surface coating on a mild steel shaft substrate. However, when such a component is subjected to fluctuating loads in service the fatigue properties, as well as the corrosion properties, of the overlay weld are of importance. Fatigue crack propagation studies have thus been carried out o...
A safety critical weld joining a central post to a cross member of a weight training leg press failed due to fatigue crack propagation from the fluctuating loads experienced in service. A comparative stress analysis carried out on the failed weight training leg press and a superficially similar leg press which had given satisfactory service reveale...
Curso de "Caracterización de Materiales Metálicos: Estructura-Propiedades". (1995).
Departamento de Ingeniería Química y Metalurgia. Facultad de Química. División III. Universidad de Barcelona. Nivel: Diplomatura. Curso de Postgrado.
BOOK 1995. 590p
All areas of industry are affected by premature failure of components which must be investigated so as to avoid future repetition. However, the complexity of the interrelations between design stress and environment often makes this a daunting task, except for the engineer with considerable knowledge or experience in failure analysis. Modern develop...
The production of a high quality corrosion resistant clad surface by overlay welding necessitates weld beads with predetermined constant geometry, low levels of defects and a low dilution. These bead characteristics are influenced by the overlay welding parameters selected and therefore knowledge of the relationship between process parameters and b...
The influence of pre-training heat treatments on the amount and repeatability of the two way shape memory (TWSM) effect developed in Cu-Zn-Al shape memory compression springs is studied. Pre-training heat treatments were achieved by flash heating in a fluidised bed for various times at temperatures between 200°C and 450°C. Training was carried out...
The influence of the amount of deformation induced during training and the time elapsed between quenching after betatising and training of the two way shape memory effect (TWSME) developed in Cu-Zn-Al shape memory compression springs is studied. Training was carried out by the constraint ageing (stabilised stress induced martensite) method and TWSM...
Determinación de las Temperaturas de Transformación Martensítica de Aleaciones con Memoria de Forma Mediante Análisis Termomecánico
J.M. Guilemany, J. Fernández, B.G. Mellor.
Revista de Tratamientos Térmicos. Nº 30, pp19 -26. Madrid .Spain. (1995).
On Springs with Two Way Shape Memory Obtained by Stabilised Stress Induced Martensite Training Methods
J.M. Guilemany, B.G. Mellor, J. Fernández, R. Franch, S.E. Willot.
European Symposium on Martensitic Transformation.C2- Barcelona.1994.Spain
Cracking by a hydrogen embrittlement mechanism has been observed in various maraging steel Bourdon tubes. The manufacturing process involved bending the tubes after filling with a low melting point alloy which is subsequently melted out. However incomplete removal of the low melting point alloy occured leading to dissimilar metal corrosion in servi...
The influence of the amount of deformation induced during training and the time elapsed between quenching after betatising and training of the two way shape memory effect (TWSME) developed in Cu-Zn-Al shape memory compression springs is studied. Training was carried out by the constraint ageing (stabilised stress induced martensite) method and TWSM...
Two Way Shape Memory Effect Obtained by Stabilised Stress Induced Martensite in Single and Polycristals
J.M.Guilemany, J.Fernandez, F.J.Gil, B.G.Mellor
Invited Talk. Réunion de Travail sur les AMF. Institut Française. Universidad Politécnica de Catalunya. Julio . Barcelona. Spain.(1993).