67065 - Metallurgy with Laboratory

Learning outcomes

The course aims to provide students with a solid knowledge of the main alloys used in industrial applications. In particular, it focuses on (i) production methods and processing technologies; (ii) effects of production processes and heat treatments on microstructures and mechanical behavior; (iii) selection and use criteria for the production of mechanical components operating under specific service conditions (iv) identification of the main mechanisms of failure and degradation of the structural components and analysis of the appropriate countermeasures. Particular attention will be devoted to presenting the main microstructural, fractographic and mechanical characterization techniques of metals and alloys.

Course contents

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

Production of metals and alloys: Production of metals from raw material and recycling. Primary and secondary metallurgy. Outline of steelmaking and production of light alloys. Recycling of metallic materials. Sustainability of production processes - Critical Raw Material (CRM).

Industrial process technologies: Definition and classification of the main manufacturing processes.

• Processes based on plastic deformation, such as forging, hot and cold rolling, extrusion, and drawing processes.
• Transient (sand casting) and permanent (gravity, pressure, and continuous casting) foundry processes.
• Autogenous welding processes based on gas, electric arc, plasma and laser source or friction.
• Additive manufacturing technologies: (i) powder bed (Powder Bed Fusion) and (ii) direct deposition (Direct Energy Deposition)

Reminders of the Fe-C phase diagram. Phases and micro-constituents. Cooling and solidification of steels and cast irons in equilibrium conditions. Equilibrium microstructures of carbon steels. Effect of the main alloying elements. Designation and classification of ferrous alloys according to Euronorm.

Isothermal and anisothermal phase transformation in steels. Ferritic, pearlitic, bainitic and martensitic phase transformations. Time Temperature Transformation (TTT) and Continuous Cooling Transformation (CCT) curves.

Heat treatments and thermochemical diffusion treatments of steels: Annealing (full, isothermal, recrystallization), normalization, quenching and tempering. Quenched and tempered steels. Carburising and nitriding treatment. Case hardening and nitriding steels. Influence of thermochemical treatments on wear and fatigue resistance.

Stainless steel: Designation: austenitic, ferritic, martensitic, duplex, precipitation hardening stainless steel. Alloying elements. Heat treatments. Physical, mechanical, and technological properties. Main application fields.

Aluminium alloys. Designation. Alloying elements. Heat treatments. Physical, mechanical, and technological properties. Main application fields.

Titanium alloys: Designation. Alloying elements. Heat treatments. Physical, mechanical, and technological properties. Main application fields.

Degradation phenomena of metallic materials: Fatigue and creep phenomena. Failure analysis with case studies.

Laboratory activities

Metallographic analysis: Methods and techniques of image analysis for quantitative metallography. Sampling procedures and sample preparation for microstructural analysis. Metallographic preparation and optical metallography of steels subjected to different heat treatments (annealing, normalizing, quenching, and tempering). Hardness profiles on specimens subjected to surface hardening and carburizing treatment.

Microstructure of non-ferrous alloys: Observation of typical microstructures of aluminum and titanium alloys produced by conventional processes and additive manufacturing.

Thermal analysis: Fundamentals of DSC analysis. DSC data processing of aluminum alloys. Effects of high temperatures on aluminum alloys: elaboration of overaging curves.

Failure analysis by scanning electron microscopy (SEM): Sampling procedures and sample preparation. Analysis of the fracture surfaces of metallic materials by scanning electron microscope (SEM). Analysis of fracture morphologies based on alloy microstructure, loading and service conditions.

Readings/Bibliography

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

Recommended reference texts:

W.D. Callister “Fundamentals of Materials Science and Engineering”, J.Wiley and Sons (2001)

D.R. Askeland, P. Webster "The science and engineering of materials", Chapman & Hall (2007)

Teaching methods

Classroom lectures according to the timetable as well as to health and safety protocols. Interactive learning tests on the main concepts. Audiovisuals on the main (i) concepts and processes (ii) metallurgical lab methods. This course participates in the innovative teaching project of the University of Bologna.

Assessment methods

Examination in English can be arranged by previous contact with the teacher.

The final exam aims at assessing if the student learned:

• The main methods of production and processing of metallic materials;
• The Fe-C phase diagram, with particular attention to equilibrium phase transformations and solidification mechanisms. Isothermal and anisothermal phase transformations and relative microstructures. Thermochemical diffusion treatments of steels
• The main topics concerning stainless steels, aluminum and titanium alloys, such as: microstructures, heat treatments, mechanical properties and uses
• The main causes of failure in metallic materials

The final exam, to be taken after the end of the course, is divided into three parts and can be taken after enrolling through AlmaEsami:

• Laboratory: the assessment in 30/30 consists of a practical test (laboratory reports in written form) which evaluates the level of knowledge acquired by the student on the characterization techniques for metallic materials. The deadlines for the delivery of the reports for each exam session will be communicated in advance via email alerts. The deadline will generally be eight working days before each exam session.
• Metallurgy: the exam consists of 2 parts:

1. Written test (multiple choice quiz, duration: 45 minutes) followed by
2. Oral exam (open questions, maximum duration: 45 minutes)

Both are rated 30/30 and must be argued in the same appeal.

The written test (multiple choice quiz) is delivered via EOL and consists of 30 questions with 4 options, of which only one is true. The 30/30 rating is calculated as follows:

• + 1 pt for each correct answer
• 0 points for each omitted answer
• - 0.25 pt for each incorrect answer

To access the oral test, the candidate must have passed the written test (minimum score: 18/30) and have obtained an assessment of more than 18/30 for the laboratory reports (even if evaluated in a previous session).

The final assessment is calculated as the weighted average of the marks acquired in the 3 parts (written exam: 30%; laboratory reports: 30%; oral exam: 40%).

Sample questions for written test (multiple choice test) and oral exam (open questions) are available in the learning material provided via VIRTUALE for this course. It is not allowed to consult notes, books or digital material during the test. No calculator is required.

Teaching tools

Classrooom lectures with both PC/slide projector and blackboard. Online lectors via Teams. Interactive sessions for learning assessment (no grading). Students are encouraged to attend Metallurgy classes in order to improve their final learning outcomes. The course attendance is not mandatory and it does affect the final examination score. Services for students with special needs and students with specific learning disabilities may be arranged on request (https://www.unibo.it/en/services-and-opportunities/guidance-and-tutoring/disabled-and-dyslexic-students-service).

Office hours

See the website of Gianluca Di Egidio