30131 - Mechanical Metallurgy M

Learning outcomes

The aim of this course is to illustrate the mechanical behaviour of metallic materials, under different service conditions. Starting from the basic relationship between microstructure and mechanical properties, the main metallurgical aspects influencing the static and fatigue resistance, the low and high temperature behaviour, as well as the wear resistance, will be presented and discussed. The effects of the production technique, including solidification conditions, plastic deformation, heat treatment or surface engineering modifications, will be evidenced. The characteristics of the main engineering metallic materials will be presented, including: iron-based alloys, aluminium and titanium alloys, metal matrix composites. By the end of this course one should have the ability to select the material and the processing conditions more suitable for the design and construction of reliable mechanical components.

Course contents

Course introduction. Presentation of course contents, teaching method and materials, assessment methods.

Plastic deformation of metals based on dislocations theory. Cold plastic deformation and strain hardening. Warm and hot working: recovery and recrystallization processes.

Overview of the innovative production processes of metals: Vacuum Arc Remelting, Electro-Slag remelting, Powder Metallurgy.

Extra-low carbon steels for cold forming: Interstitial Free e Bake Hardening steels. Carbon-manganese steels for structural applications and high strength low alloy steels (HSLA). Multi-phase advanced high strength steels: Dual-Phase (DP) and Transformation Induced Plasticity (TRIP) steels.

Special steels for highly stressed components. Hardenability of steels and tempering curves. Quenched and tempered steels. Springs and bearings steels. Tool steels. Bainitic steels. Maraging steels. Carburised, nitrided, carbonitrided and nitrocarburised steels.

Stainless steels: ferritic, martensitic, austenitic, duplex and precipitation hardening. Chemical composition, heat treatments, physical and mechanical properties, application fields.

Cast irons. Lamellar, spheroidal, vermicular, austempered and white cast irons. Chemical composition, designation, heat treatments, physical and mechanical properties, application fields.

Cast and wrought aluminium alloys. Designation, alloying elements, strengthening mechanisms, heat treatments, microstructure, physical and mechanical properties, application fields.

Titanium alloys. Production, alloying elements, strengthening mechanisms, heat treatments, microstructure, physical and mechanical properties, application fields.

Fatigue. The role of crystal structure and dislocation on fatigue failure. Main fatigue tests. Metallurgical and mechanical aspects of fatigue. The role of solidification defectes, heat treatment and surface modification techniques on fatigue strength. A short introduction to linear elastic fracture mechanics: stress intensity factor and fracture toughness. Case studies on fatigue failed components.

Tribology. The theory of friction and its control. Processes and mechanisms of wear of main mechanical components. Selection criteria of materials and treatments to control friction and wear. Case studies on mechanical components subjected to tribological problems.

Case studies and criteria of materials selection. Case studies of failure are presented and discussed to explain the correct choice of materials, depending on the type of mechanical component and its operating conditions.

A video-presentation of the teaching is available through the Links to further information, at the bottom of the page.

Readings/Bibliography

Course Material (slides and notes in Italian). All the slides used by the teacher are available in the VIRTUALE repository, as password-protected pdf files (in Italian).

Specific references are reported at the end of the slides for each subject of the course.

Teaching methods

The course consists of:

- Lectures according to the timetable.

The teacher also proposes:

- Optional visits to the Metallurgy laboratory to illustrate the main equipment and methods for the microstructural and mechanical characterization of metals

- Seminars on specific topics held by people working in mechanical / motor companies

Assessment methods

Achievements will be assessed by means of a final oral exam. Foreign students may ask for a written exam.

The oral session consists of 2-3 questions aimed to an analytical assessment of the expected learning outcomes, that are:

1. Knowledge of the main properties of structural metallic materials of major industrial use.

2. Ability to make the correct choice of the most suitable material and treatment to satisfy specific functions in use.

To obtain a passing grade, students are required to demonstrate a knowledge of the key concepts of the subject and a comprehensible use of technical language. A failing grade will be awarded if the student shows knowledge gaps in key-concepts of the subject and an inappropriate use of technical language. Higher grades will be awarded to students who demonstrate an organic and deep understanding of the subject, a good capability of connecting different topics and a proper use of technical language.

Examinations schedule is available in advance on the University of Bologna web site AlmaEsami.

Teaching tools

The lessons are based on the use of slides (available on the VIRTUALE repository, before each lesson), a traditional blackboard or tablet, and video for teaching support. Attendance is recommended for a better learning of fundamental concepts.

Visits to the Metallurgy laboratory are proposed (tools and methods for the microstructural and mechanical characterization and the metal failure analysis).

Any tools for students with disabilities can be agreed with the DSA Student Service of UNIBO.

Links to further information

https://youtu.be/J5xFC6dP7qw

Office hours

See the website of Lorella Ceschini