Engineering Materials

Ter frequentado as seguintes unidades curriculares da Licenciatura em Eng. Mecânica do ISEC:

– Química.

– Fundamentos de Ciência dos Materiais.

Teaching methodology is based in lectures, theoretical-practical lessons and laboratory practices. The lecturing sessions are primarily dedicated to presenting contents, using the board and the projection of slides. In conducting these sessions, student participation is often raised by formulating questions that lead them to reflect on the subject matter and create opportunities for clarifying concepts. It is reserved for the theoretical-practical lessons the presentation and exploitation of specific parts of the unit syllabus whose nature provides a more applied and interactive approach. In practical classes, students carry out experimental works in small groups, comprising the use of metallography techniques, the interpretation of microstructures and the performance of thermal treatments.

The main objectives of the course unit are: To enhance knowledge about the composition, structure, properties, applications and processing of different engineering materials, focusing mainly on ferrous metallic materials; To provide hands-on experience in the use of metallographic techniques and interpretation of microstructures, as well as in the conduction of common heat treatments. The completion of this unit will enable to achieve, or contribute to achieving, the following competences: Capacity to describe and understand the structure, specific properties, potential applications and processing methods of a wide range of engineering materials; Ability to perform different heat treatments and understand their effects; Ability to use experimental techniques for the characterisation of materials; Capacity to report, analyse and discuss experimental results; Capacity to search, select, organise and communicate information; Ability to work in small groups.

1. Industrial production of ferrous alloys
Circular economy concept and its relationship with the production and use of metallic materials. Raw materials from the steel industry. . Elaboration of steel and cast iron. Casting and processing of steel.
2. Iron-carbon alloy system
Analysis and Interpretation of the Metastable and Stable Equilibrium Diagram of the Ferro-Carbon Alloy System:
Metastable System: hypoeutectoid, eutectoid and hypereutectoid steels. Hypoeuthetic, eutectic and hypereutectic white cast iron.
Stable System: Hypoeuthetic, eutectic and hypereutectic gray cast iron.
Chemical Composition, Relative Amount of Phases, Relative Amount of Microconstituents and Microstructure of the different alloys studied.
3. Cast iron
Unalloyed cast iron: Chemical composition; Properties of microstructural constituents of cast iron; Types of graphite; Relationship between the type of graphite and the mechanical properties of cast iron; White cast iron; Gray lamellar graphite cast iron; Spheroidal and malleable graphite cast iron.
Alloyed cast iron.
4. Classification of steels
Classification of steels according to their chemical composition: non-alloyed and alloyed steels; Classification of steels according to other criteria.
5. Non-alloyed steels
Microstructures resulting from the transformation of austenite: Transformation of austenite with diffusion – influence of the cooling rate; Martensitic transformation; Bainitic transformation. Properties of microstructural constituents of steels. Relationship between microstructure, mechanical properties and application of steels.
6. Alloyed steels
Limitations of non-alloy steels. Goals of adding alloying elements. Distribution of alloying elements: carbide and non-carbige elements. Influence of alloying elements on Fe-C balance: Influence on the extension of the austenitic domain; Influence of alloying elements on the microstructural constituents of steels.
7. Heat treatment of steels
Austenite transformation diagrams: Isothermal austenite transformation; Transformation of austenite into continuous cooling; Influence of alloying elements and austenitization conditions; Annealing heat treatments.
Quenching: Austenitization; Quench critical speed; Tempering means; Hardenability, hardening penetration, hardening depth and maximum hardness concepts; Factors influencing the hardenability of steels; Determination of hardenability and characteristics after hardening – hardenability tests; Tempering defects; Austempering; Martempering.
Tempering: Tempering steps in unalloyed steels; Influence of alloying elements on tempering – secondary hardening.
Surface hardening treatments
8. Polymeric materials
Characterization and classification of polymeric materials. Polymerization reactions and molecular weight; Homopolymers and copolymers. Structure of polymeric materials: Linear, branched and crosslinked polymers; Amorphous and semi-crystalline polymers. Mechanical behavior of polymeric materials: Deformation mechanisms; Relationship between structure and mechanical properties; Glass transition temperature. Characterization and applications of the most representative thermoplastic, thermosetting polymers and elastomers.
9. Introduction to metallographic characterization techniques
Preparation of metallographic samples before and after heat treatments. Comparative study of microstructures and hardness of non-alloyed steels before and after heat treatments. Microscopic observation of metallographic samples of different types of steel and cast iron.

• Assessment Components:
The knowledge assessment comprises the following components:
1- Final exam, covering the the theoretical and theoretical-practical classes;
2- Oral presentation and discussion in the practical classes of a written research and bibliographic report, focusing on a specific topic within the subject matter.
3- Questions presented in the T/TP classes, without prior disclosure to students, related to the topics covered in the current class or in recent classes.

• Final Classification:
The final assessment is based on a score on a scale of 0 to 20 points, with the following rules used to determine the final grade:
1- A weighting of 70% for the exam score and 30% for the presentation of the research and bibliographic report.
2- An additional weighting of up to 1 point is assigned to the answers to the questions presented in the T/TP classes. This weighting is calculated only in the academic year in question and at all assessment periods.

• Approval Criteria:
To take the written exam, students must have been evaluated on the research and bibliographic synthesis report (evaluated component) and attended at least 75% of the practical classes, related to the execution of the experimental work (non-evaluated component).
- Passing the course requires a final grade of at least 10 points and is conditioned on obtaining a minimum grade of 8 points on the exam and 10 points on the research and bibliographic synthesis report.
- The research and bibliographic report is considered in the final grade in the academic year in which it was completed and in the two subsequent academic years.
- If the student takes the exam in academic years after those indicated in the previous item, the evaluation will only include the exam, with the final grade determined only by the score obtained on this test.

• Notes:
- The research and bibliographic report is made in groups and presented and discussed by the last week of classes.
- Students enrolled as student workers, if they are effectively unable to attend practical classes, must submit and discuss an individual report on the topics covered in those classes.
- Exams taken outside of the assessment periods specified in the school calendar, may take the form of an oral exam.

NAO