PAOLO MATTEIS

Associate Professor

Photo
Phone +39 0110904711 / 4711 (DISAT)
Email paolo.matteis@polito.it
Scientific branch ING-IND/21 - METALLURGIA
(Area 0009 - Ingegneria industriale e dell'informazione)
Publications PORTO - Publications Open Repository TOrino
Curriculum
CAREER
1976/2/9 - Born in Torino, Italy.
July 1994 - Scientific high school degree, 60/60 (maximum) mark, at the Liceo Aldo Moro, Rivarolo Canavese, Torino, Italy.
2000/3/10 - M.Sc. (“Laurea di vecchio ordinamento”) in Materials Engineering, metallurgical orientation, 109/110 mark, at the Politecnico di Torino (Turin Technical University), Torino, Italy. Dissertation: “Study of the magnetic-thermal-metallurgical-mechanical effect caused by a induction quenching / relieving process: experimental analysis and numerical validation with F.E.M. software”.
May 2000 - Italian Government habilitation for the profession of engineer.
2000/4/1 - 2000/5/31 - Contract researcher (with "Contratto di lavoro occasionale") at the Materials Science and Chemical Engineering Department (DISMIC) of the Politecnico di Torino.
2000/8/22 - 2001/6/19 – Mandatory military service in the Italian Army.
2001/6/20 - 2003/1/24 – Work for O.M.P. S.r.L. company of Busano (To), Italy, having about 150 employees, active in the mechanical machining of metal parts for heavy and construction vehicles. Tasks performed (in different periods): procurement of direct material, machining services, and special tools; industrialization of new products; preempting; writing of corporate quality standards; installation and partial development of corporate IT system.
2003/1 - 2006/5/5 – Ph.D. course in Metallurgical Engineering at the Politecnico di Torino, with university grant. Dissertation: “Fracture toughness of plastic mold steels: dependence upon the production cycle, the heat treatment and the microstructure”.
2006/2/16 - 2006/4/14 - Contract researcher ("Contratto di collaborazione coordinata e continuativa") at the DISMIC. Task: research activity in the field of mold steels.
2006/4/15 - 2008/9/30 - Research assistant ("Assegnista di ricerca") at the DISMIC. Project: “Mechanical properties and applications of amorphous and microstructured alloys”; scientific sector Ing-Ind/21 - Metallurgy.
2008/10/1 - 2014/9/30 - Assistant Professor (“Ricercatore”) at the Politecnico di Torino, member of the 1st Faculty of Engineering and of the DISMIC, until they were deactivated on 2011/12/31, and of the new Department of Applied Scince and Technology (DISAT) thereafter; member of the call sector ("Settore concorsuale") 09/A3 - Industrial design, Industrial design, machine construction and metallurgy and of the scientific sector ("Settore scientifico-disciplinare") Ing-Ind/21 - Metallurgy; confirmed ("Confermato") in the same position on 2011/10/1.
2014/10/1 - present - Associate Professor at the Politecnico di Torino, member of the DISAT, of the call sector 09/A3 and of the scientific sector Ing-Ind/21

RESEARCH
He is the author of more than 20 journal papers, mostly on international peer reviewed journals, and he contributed to more than 40 international and 20 national conferences. Most of his work was devoted to the research lines which are described hereafter.
Microstructural effects of explosive shock waves - In this research (relevant for the fields of physical metallurgy, forensic metallurgy, and explosives characterization) the threshold conditions, beyond which a shock wave caused by a small explosion will yield permanent and detectable effect in a metal target, even in the absence of macroscopic deformation, were studied.For this purpose, the microscopic plastic deformation phenomena in threshold conditions were examined, both theoretically and experimentally, by subjecting specimens of different alloys, all with a face centered cubic structure, to the shock waves caused by the explosion of small plastic explosive charges. The competition between the slip and twinning deformation mechanisms, also in relationship to the stacking fault energy of the alloy (depending on its composition), as well as the experimental methods useful to detect the mechanical twins, were especially studied. The first experiments were performed on an austenitic stainless steel; then a gold alloy, pure copper, an aluminum alloy, and an α brass were also studied, and the result obtained with the different alloys were thoroughly compared.
Plastic mold steels - This research concerned the microstructural and mechanical properties of the plastic mold steels, which are used to manufacture very large molds (e.g. for automotive dashboards and bumpers). These large mold exhibit mixed microstructures, including tempered martensite, bainite and pearlite, with variable amounts as a function of the distance from the original bloom surface. At the beginning, the fracture toughness and other mechanical properties of the most commonly used steel were examined as a function of the heat treatment, the microstructure, and the position inside the original heat-treated bloom. This study was then extended to the fatigue behavior, with both stress-life and fatigue crack growth tests.The low fracture toughness of the mold steels was related to the mixed microstructures encountered in the large blooms. For this reason, a thermo-metallurgical model of the quench process was implemented and the thermal diffusivity of the different steel constituents was measured in the relevant temperature intervals. Thereafter, the microstructural and mechanical properties of some alternative plastic mold steel grades (for large molds), and especially the aging process of one of them, were studied, and the fatigue behavior of the different steels was compared with fatigue crack growth tests. Finally, a global comparison of the different steels was completed and published.
Bulk metallic glasses - In this research the mechanical properties of amorphous metallic alloys were studied, both theoretically and by means of compression experiments of bulk specimens of copper - zirconium based alloys, further alloyed with aluminum, and with or without yttrium. It was found that, whereas the alloys with yttrium do not offer any plastic deformation, those without yttrium exhibit a peculiar plastic behavior, consisting of a series of discrete events. The influence of the crystalline precipitates, formed in some of the examined alloys (with volume fraction up to 20 %), on the plastic deformation of the same alloys, was also reported. The compressive test results were also examined statistically and correlated with the fracture mechanisms, as observed by scanning electron microscopy.
Car-body sheet steels - This research has been stimulated by the recent development and application of new steel grades for car-body parts, characterized by a great variety of microstructures and strengthening mechanisms, which are fabricated in the form of sheets and undergo continuous heat-treatment processes immediately after cold rolling. The study was mainly devoted to the microstructure and mechanical properties of the steel sheets, both as fabricated (after the continuous heat treatment) and after the cold-forming and welding processes which are employed in the car industry. Moreover, plastic deformation instability phenomena of the Portevin - Le Chatelier type were observed during room-temperature tensile tests on the austenitic high-manganese steels, with several and complementary methods. More recently, attention was focused on dissimilar welding between the austenitic high-manganese steels and the low alloy grades.
Failure analysis and prevention - This line of research was derived from several failure analyses, often (but not always) related to judiciary investigations or trials, either civil or criminal.
Other research - A line of research was devoted to elucidate the damage mechanisms which affect the steel dies which are used in the aluminum extrusion process, which are fabricated with hot work tool steel and usually undergo several nitrocarburizing and service cycles. Another line of research was devoted to correlate the high-temperature mechanical performance and the fracture mechanisms of a cast cobalt alloy with its dendritic microstructure, by means of crystallographic and microstructural investigations, tensile and fatigue mechanical tests at high temperature, and fractographic examinations. In yet another work, the effectiveness of different corrosion protection methods was studied, with regards to the issue of localized corrosion on mechanical junctions between cast magnesium alloy parts and either aluminum alloy, or coated steel, counterparts; this issue being especially important for the usage of magnesium alloys in the automotive industry. Finally, in yet another branch of research, previous results on the notch sensitivity of quenched and tempered steels, as a function of the tempering temperature, were reviewed and explained by means of elastic-plastic simulations.

TEACHING
The candidate has been the appointed teacher ("titolare") of one module ("insegnamento") at the Politecnico di Torino in each academic year from 2006-2007 to present. In particular, he was the appointed teacher of the following modules, taught in Italian:
• MECHANICAL METALLURGY (“Metallurgia meccanica”, 5 credits), part of the M.Sc. Course ("Laurea Specialistica") in Mechanical Engineering of the 2nd Faculty of Engineering, in the academic years from 2006/2007 to 2009/2010 included.
• TECHNOLOGY OF CONSTRUCTION MATERIALS (“Tecnologia dei materiali da costruzione”, 6 credits), part of the M.Sc. Course in Civil Engineering of the 1st Faculty of Engineering, in the academic year 2010/2011.
• TECHNOLOGY OF METALLIC MATERIALS (“Tecnologia dei materiali metallici”, 5 credits), part of the remote B.Sc. Course ("Corso di Laurea a distanza") in Mechanical Engineering of the 1st Faculty of Engineering, in the academic year 2011/2012.
• MATERIALS FOR THE MECHANICAL INDUSTRY (“Materiali per l’industria meccanica”, 6 credits) part of the M.Sc. Course in Mechanical Engineering, in the academic years from 2012-2013 to present
Moreover, the candidate gave lectures and exercises as a collaborator teacher for several modules pertaining to the B.Sc. or M.Sc. courses in Mechanical Engineering, Automotive Engineering or Civil Engineering of the Politecnico di Torino, mostly in Italian, but some in English.
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