Microstruttura e proprietà termofisiche degli acciai per bonifica - Applicazioni per la simulazione ed ottimizzazione della tempra

Presentazione orale ed in atti all'incontro tecnico "Applicazioni industriali della misura delle proprietà termiche dei metalli - Nasce la Evitherm Society",Assotec,Milano,9/3/200

Some comments on mechanical fatigue characterization of steel rails in Standards

Current Standards and recommendations on characterization of steel materials for rail production define tests for material supplying. As reported in technical literature, fatigue is the phenomenon which represent one of the main cause of rail damage and failure. Experimental testing of fatigue characterization according to Standards on different samples and with different surface roughness values, satisfying the Standard requirements, are performed. The results are then presented and discussed. Some nomenclature ambiguities are pointed out, which can lead to different loading conditions for fatigue testing

Variations of the elastic modulus of automotive steels after yielding

Presentazione orale al convegno TMS 2011 Annual Meeting & Exhibition, svoltosi a San Diego, USA, dal 27/02/2011 al 03/03/201

Tenacità a frattura di acciai per stampi per materie plastiche: dipendenza dal ciclo produttivo, dal trattamento termico e dalla microstruttura

Tenacità a frattura di acciai per stampi per materie plastiche: dipendenza dal ciclo produttivo, dal trattamento termico e dalla microstruttur

Conservazione e sicurezza strutturale di colonne in ghisa prodotte e montate in opera nel XIX secolo

riassunto esteso e presentazione orale al convegno Workshop IGF - Problematiche di Frattura nei Materiali per l'Ingegneria, Forni di Sopra (UD), 7/1/2010 - 9/1/201

On plastic notch effects in quenched and tempered steels

Presentazione orale al convegno TMS 2010 - 139th Annual Meeting & Exhibition, svoltosi a Seattle (USA) dal 14/02/2010 al 18/02/201

The way the mistery of the Mattei's case was solved

Enrico Mattei, the President of the Italian oil conglomerate, ENI, was about to land in Milan Linate Airport on October 27, 1962 when his airplane crashed on the ground due to a then unexplained accident. The investigation, reopened more than 30 years later, implied complete re-examining of the theories on macroscopic and lattice deformations under high velocity waves emanating from a small charge explosion.Various macro- and micro-structural changes are induced by an explosion and by the resulting shear stresses in metals exposed to it. At the microstructural level multiple slip bands or mechanical twins, induced from the pressure wave caused by an explosion, can be observed. The occurrence of either ones depend on the type of metal, the pressure and the strain rate. The temperature wave may also cause surface alterations. Different situations regarding stainless steels, aluminium, copper and gold alloys are analysed.Calculations to evaluate which deformation mechanism is eligible for different FCC metals and alloys are reported. Results of field explosion experiments are incorporated into the evaluation of microstructural signs possibly induced on metal targets by an unknown explosive event.Revisited theories were applied to the Mattei forensic case, reaching the conclusion that the aircraft had fallen following an on board small charge explosion

Fatigue resistance of light alloy sheets undergoing eco-friendly chemical milling: metallurgical and chemical aspects

Abstract Component lightening is a key issue for automotive and aerospace industries. Lightening processes on design profile are not always possible by means of traditional machining processes. Then, chemical milling processes are used, often by acid etching. The effect on fatigue behavior is related on many factors, such as chemical surface composition and surface roughness. Material removal through chemical milling is in particular interesting for Additive manufactured components where surface finish still remains a parameter difficult to be controlled and repeated. The environmental aspects related to alkaline and acid processing are still an important issue. In the present paper, an overview on chemical milling for component lightening is presented with focus of the effects on mechanical and chemical resistance of materials. Then, the results of an experimental campaign on an aluminum alloy is presented. In particular, high cycle fatigue tests results are presented on specimens subjected or not subjected to an eco-friendly alkaline chemical milling process (called " Green Etching") and chemical, profilometric and metallographic analyses are presented and related to fatigue resistance results. Wettability and surface charge results will be presented

Using ground motion prediction equations to monitor variations in quality factor due to induced seismicity: a feasibility study

Sub-surface operations for energy production such as gas storage, fluid reinjection or hydraulic fracking may modify the physical properties of the rocks, in particular the seismic velocity and the anelastic attenuation. The aim of the present study is to investigate, through a synthetic test, the possibility of using empirical ground-motion prediction equations (GMPEs) to observe the variations in the reservoir. In the synthetic test, we reproduce the expected seismic activity (in terms of rate, focal mechanisms, stress drop and the b value of the Gutenberg-Richter) and the variation of medium properties in terms of the quality factor Q induced by a fluid injection experiment. In practice, peak-ground velocity data of the simulated earthquakes during the field operations are used to update the coefficients of a reference GMPE in order to test whether the coefficients are able to capture the medium properties variation. The results of the test show that the coefficients of the GMPE vary during the simulated field operations revealing their sensitivity to the variation of the anelastic attenuation. The proposed approach is suggested as a promising tool that, if confirmed by real data analysis, could be used for monitoring and interpreting induced seismicity in addition to more conventional techniques