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. 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 and magnesium alloys. Designation, 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.

Failure analysis. Fractography and Metallography.

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

Readings/Bibliography

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

Specific references are reported at the end of the slides for each subject of the course, with a glossary of the main Italian / English terms.

Teaching methods

Classroom and/or onlines lectures according to the timetable and to the COVID emergency. All the slides used by the teacher are available in the Moodle repository, before each lesson.

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

- Visits to companies operating in the metallurgy and heat treatment sector.

For many of the topics discussed in class, examples of company collaborations are presented to support the correct choice of materials, in relation to the specific component and its operating conditions.

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. Knowledge of the main tools and methods for the microstructural and mechanical characterization of metallic materials.

3. 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. Students willing to take the exam must join the student list on the web site AlmaEsami, carefully considering deadlines for student list opening and closing. Further exam dates can be defined with the teacher upon agreement by e-mai. Students are required to show their own ID before taking the exam

Teaching tools

The lessons are based on the use of slides (available on the IOL 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.

Office hours

See the website of Lorella Ceschini