Course detail
Processing of Special Castings
FSI-PLI Acad. year: 2021/2022 Winter semester
The technology of producing castings of heat-resistant alloys of nickel and cobalt, titanium alloys, permanent magnet castings. Fundamentals of vacuum metallurgy, application of vacuum induction melting, vacuum arc remelting, electron-beam remelting. Electroslag remelting and casting process.
Supervisor
Department
Learning outcomes of the course unit
Students will learn about the effect of reduced pressure on molten alloys, about heat control processes in vacuum induction furnaces, vacuum arc furnaces, vacuum electron-beam furnaces, and about methods for controlling the crystallization of special castings. They will further learn about the types of airpump used and about measuring low pressures. They will be taught the basic metallurgical calculations used in the design of heat control processes in vacuum.
Prerequisites
Students must have the knowledge of the thermodynamics of metallurgical processes (properties of real solutions, the criterion of the progress and equilibrium of metallurgical processes, equilibria in the melt/gas and melt/refractory systems) and the crystallization theory of foundry alloys (nucleation models, transport processes in the phase of crystal growth, morphology of phase interface).
Planned learning activities and teaching methods
The course is taught through lectures explaining the basic principles and theory of the discipline. Exercises are focused on practical topics presented in lectures. Teaching is suplemented by practical laboratory work.
Assesment methods and criteria linked to learning outcomes
Condition of awarding the course-unit credit: participation in exercises. Examination: the knowledge of physical-chemical foundations of vacuum metallurgy, practical application of vacuum metallurgy, and controlled crystallization of special castings will be tested. It is a written and oral examination.
Language of instruction
Czech
Aims
The objective is to familiarize students with the application of vacuum and other special technologies in the preparation and casting of special alloys, and the possibilities of controlling the crystallization of these alloys.
Specification of controlled education, way of implementation and compensation for absences
Attendance in lectures is recommended, attendance in exercises is obligatory.
Attending at the exercises is required, being checked by the leader of practicals. In the case of absence from exercises, the leader assigns a topic for independent written work.
The study programmes with the given course
Programme N-SLE-P: Foundry Technology, Master's
branch ---: no specialisation, 4 credits, compulsory-optional
Type of course unit
Lecture
26 hours, optionally
Teacher / Lecturer
Syllabus
1. Basic characteristics of gaseous mixtures in the region of low gas pressures
2. Thermal dissociation of gas compounds, equilibrium gas pressure
3. The process of carbon reaction in vacuum
4. Dissolution of gases
5. Degassing in vacuum
6. Evaporation of alloy components
7. Casting in induction and electron beam vacuum furnaces
8. Theoretical foundations of controlling the crystallization of metals
9. Production of castings with equiaxial grains, controlling the grain size
10. Castings with oriented columnar grains, single crystals
11. Permanent magnet castings with oriented columnar grains
12. Production of castings of titanium alloys in vacuum furnaces
13. Electroslag castings
Laboratory exercise
12 hours, compulsory
Teacher / Lecturer
Syllabus
1. Basic design nodes of the vacuum furnace, valves, sealing (laboratory for vacuum metallurgy)
2 Practical application of vacuum gauges, limit pressure of vacuum pumps (laboratory for vacuum metallurgy)
3. Viewing visit to the foundry of special castings. Preparation of ceramic shell moulds, vacuum induction furnaces for metallurgy and foundries
4. Practical demonstration of the progress of melting in vacuum induction furnaces (laboratory for vacuum metallurgy)
5. Creep test of heat-resistant alloys (creep laboratory)
6. Hot isostatic pressing of castings at high temperatures (HIP laboratory)
Computer-assisted exercise
14 hours, compulsory
Syllabus
1. Methods for obtaining vacuum, basic types of vacuum pumps
2. Basic types of vacuum gauges used with melting vacuum furnaces
3. Determination of dissociation tension of oxides and nitrides, practical applications
4. Possibility of blocking the carbon reaction in vacuum
5. Thermodynamics and kinetics of the formation of bubbles
6. Calculation of vapour pressure of alloy components, estimate of changes in chemical composition
7. Raw materials for the charging stock. Charging stock calculation for vacuum induction furnaces