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Politecnico di Torino
Academic Year 2016/17
01MZALZ
Science and technology of materials/Metallurgy
1st degree and Bachelor-level of the Bologna process in Aerospace Engineering - Torino
Teacher Status SSD Les Ex Lab Tut Years teaching
Lombardi Mariangela ORARIO RICEVIMENTO O2 ING-IND/22 48 12 0 0 11
Scavino Giorgio ORARIO RICEVIMENTO AC ING-IND/21 32 8 0 0 11
SSD CFU Activities Area context
ING-IND/21
ING-IND/22
4
6
C - Affini o integrative
C - Affini o integrative
Attività formative affini o integrative
Attività formative affini o integrative
Subject fundamentals
Materials play a crucial role in aerospace engineering design and. The Materials Science and Technology module is aimed to supply the student with an engineering background on materials, and in particular on those for aerospace applications, emphasizing the relationships among materials structure, microstructure and performances and, as a consequence, the potentialities of engineering design able to exploit traditional and innovative materials through the tailoring of their microstructure. A deep understanding of the property-limited selection and design is therefore the main objective of this course. Near Further to the analysis of the science scientific approach that lies behind, some specific case studies will be exploited to allow the student to understand how properties can affect materials selection and processing. In this way, science-led and design-led approaches to materials teaching will be synergically combined to offer the information that will be needed to achieve a deep knowledge and to enable a successful material selection.
The Metallurgy module aims to firmly establish fundamentals of behaviour of metallic materials especially in respect to their load carrying capacity as influenced by composition, microstructure, thermal and mechanical processing. The characteristics of metallic materials are presented. Attention is devoted to steels and their heat-treating procedures aiming to both bulk heat-treating and surface thermo-chemical treatments. The quenching and ageing processes of Al. Ti and Mg alloys are fully described. A description of applications of selected classes of steels, Al, Mg, and Ti alloys is offered aiming to guiding users to material selection in design and to quality appraisal in procurement.
Expected learning outcomes
The main aim is to supply the student with a robust background on materials, able to couple scientific and technological knowledge in a synergic way, providing general guidelines for translating scientific knowledge into technological tools for engineering design.
The student should then:
- know the chemical and atomic nature of the materials and the strong dependence of the macroscopic features and properties from it;
- know how to exploit this scientific background in controlling the material properties up to the tailoring of material features for a specific application;
- know how to select materials for matching design requirements;
- be able to develop a confident approach to materials;
- know a basic English vocabulary on Materials Science and Technology.
Prerequisites / Assumed knowledge
The student is required to have a robust, basic knowledge on Chemistry and Physics.
Contents
Materials Science and Technology: Introduction to materials classes and processes. Process-property interaction. Strategic thinking: matching materials to design. Structure of solids. Density. Stresses and loading modes. Strains. Hooke's law and Young's modulus. Stress-strain curves. Solutions for elastic design. Specific properties: how to minimize weight. Strength, plastic deformation work and ductility. Defects in crystals: dislocations and plastic deformation. Plasticity in polymers. Introduction to the strengthening mechanisms. Manipulating mechanical properties. Mechanical testing of materials and their Standards and tests. (15 h)
Fracture and toughness. Introduction to the mechanics of fracture. Griffith's theory and stress concentration: fracture toughness. Strength-toughness trade-off: metals, polymers, composites. Fatigue: cyclic loading, damage and cracking. Endurance limit. How to improve fatigue resistance. Tribological properties: friction and wear. How to manage friction and wear, lubrication. (15 h)
Thermal properties: thermal expansion, thermal conductivity. Manipulating thermal properties. Design to exploit thermal properties: sensors and actuators, heat exchangers, thermal insulators, thermal buffers. How to use materials at high temperature. Creep: curves and tests. Creep damage and fracture. Thermal barriers. (h.15)
Electric properties. Conductors, insulators, dielectrics. Piezoelectricity, piroelectricity. Ferroelectricity. Manipulating electrical properties. Dielectric losses and the stealth effect. Magnetic properties. Optical properties: materials-radiations interaction. Durability of materials: oxidation, corrosion and degradation. Flammability and photodegradation. Phenomena, consequences and guidelines to prevention and materials protection. Materials-processes-environment: introduction to life-cycle analysis and to eco-design. (h.15)
Metallurgy - Metallic phases: cubic and hexagonal lattices. Interstitial and substitutional solid solutions. Hume-Rothery phases, Laves phases, carbides. Phases diagrams: fundamentals. Analysis and description of the principal binary phases diagrams. Applications.
Precipitation hardening- Al alloys. Mechanical properties of biphasic alloys. Microstructure effect. Precipitation hardening of coherent and incoherent particles. G.P. zones, theta and theta' phases in Al-Cu alloys. Hardening after natural or artificial ageing. Thermo-mechanical treatments. Standards of Al-alloys. Mg and Ti alloys: Elektron Mg-Al alloys, Mg-Al-Zn and Mg-Zn alloys, Mg-Al-Ag alloys. Ti alloys: Ti alpha, beta, alpha-beta alloys, thermal heat treatments. (20 h)
Thermal Heat treatments of steels: eutectoidic transformation. Isothermal austenite transformation curves. Martensitic transformation, Ms and Mf. Continuous cooling transformation curves. Effect of cooling rate on the microstructure and mechanical properties of the steels. Annealing, normalizing, quenching. Jominy test. Effect of alloying elements on the Jominy curves. Quenching cracks. Tempering and tempering embrittlement. Effect of Mo.
Thermo-chemical treatments: endothermic and exothermic atmospheres. Quench and tempering cycles. Effect of thermochemical treatments on fatigue and wear résistance. Carburizing. Carbon potential of carburizing atmospheres. Influence of CO and CH4 in the carburizing. 1st and 2nd Fick's laws. Treatment time and thickness of hardened layers. Gaseous and plasma carburizing. Thermal treatments after carburizing. Nitriding. Fe-N metastable phases diagram. Leher diagram: effect of H2/NH3 mixtures and constitution of nitrided phases layers. Surface and diffusion layers. Effect of the treatment time on the diffusion depth. Nitrocarburizing. Flame and induction surface hardening. Fundamentals and application.
Carbon and alloyed steels: effect of alloying elements. Stainless steels: Cr effect. Austenitic, ferritic and martensitic steels. Structural steels. HSLA. Weldability of the steels: effect of the chemical compositions. Marageing steels: thermal treatments and applications. Tool steels: effect of Cr, Mo, W and V on tempering and secondary hardening. (20 h)
Delivery modes
A virtual laboratory is available, as a support to the theory, on the 'Portale della Didattica': http://didattica.polito.it/pls/portal30/docs/FOLDER/AREA_DOCENTE/SITO_VIRTLAB/INDEX.HTM.
Texts, readings, handouts and other learning resources
M. Ashby, H. Shercliff, D. Cebon, Materials, Engineering, science, processing and design, Elsevier (2007)
Assessment and grading criteria
Written examination will last 2 hrs; books and notes will not be available. The student will have to answer to several questions in order to witness his/her knowledge of the contents of the course. Facsimile examination forms will be available on the 'Portale della didattica'.

Programma definitivo per l'A.A.2016/17
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