18mty en - 1. materials -...
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Schedule of lectures# Title MTY #
1 Mechanical properties of materials, structure of materials 1, 2
2 Crystal structure, lattice defects 3
3 Solid solutions, thermodynamics and binary diagrams 4
4 Steel and cast iron, quenching, tempering, annealing 5
5 Fe-C diagram, special steels and alloys. Non-ferrous metals 6, 7
6 Polymers, structure, processing, mechanical properties 8, 9
7 Composites - properties, advantages, synergies, fibers and matrix 11, 12
8 Degradation of materials, nondestructive testing 13
There is only 7 lectures left before Xmas holiday, we need at least one more!Proposal some odd-week Wednesday from 15:00 to 16:30 at F008.Odd - week Wednesdays till end of this year:Nov. 7th, Nov. 21st, Dec. 5th, Dec. 19th
Informations & presentations
• http://mech.fd.cvut.cz/education/bachelor/18mty-en
• (do not exist yet, will be on-line next week)
• Syllabus
• Presentations
• …
W. Callister: Materials science and engineering. An introduction
libgen.io
Properties of materials
Bonds Structure Defects Properties
Basic schematics of Materials Science and Engineering
Structure
PropertiesProcessing
Investigation of material properties
Input OBJECT effect
A possible response of material to loading
A A2*A
𝜀 =Δl
𝑙
Ϭ=𝐺
𝐴
List of fundamental notions and terms• Relative elongation, true deformation, transversal
deformation, Poisson ratio
• Deformation elastic (reversible) a plastic (permanent)
• Force and stress, tension and compression, shear and torsion
• Elasticity, Hooke law
• Young’s modul of elasticity, stiffness vs. compliance, rigid body
• Strength, ultimate strength, yield point
• Hardness vs. softness
• Toughness vs. fragility
Why we need material tests?
Study of material properties
Material tests
Design and strength calculation
(Material parameters)
Production quality control
(improving material’s quality, analysis of failures)
Universal testing machine
Tensile testductilefragile
𝑙0 = 𝑆0 ∗ 5.6
5.6 ≈ 5 ∗4
𝜋
forc
e
elongation elongation
forc
e
forc
e
forc
e
Phase 1
Phase 2
Phase 3Phase 4
Tensile test – cont.
A…elongation (= eu)
E, Rm, A
Stress – strain curve Compression
Tensionsteel
Cast iron
Metallic foam
High strength steel
Mild steel
Alluminiumalloy
Copper alloyMagnesium alloy
Cast iron
Stress [MPa]
Strain [1]
Hardness
2.5 gold
5 toothenamel
4.5-5 nail
Engineeringmaterials
Hardness of Au alloys
Hardness tests
Vickers
Rm3*HB
𝐻𝐵 =𝐹
𝜋∙𝐷
2(𝐷− 𝐷2−𝑑2
, F[kp], d[mm2]
Rockwell hardness test. Indentation by cone
Brinnel hardness test. Indentation by sphere
Impact tests
Charpy hammer
Notches U a V Potential energydifference
Atoms and atomic bonds
Materials are hierarchical structures
Shape
Polycrystalline structure
Lattice defects
Atomic bonds
Bonds Structure Defects Properties
Size of atom
=: :
Mp=2000 * Me
Bonding potential
Tm~E0
Young’s modulus
1
E
Cohesive force
r
F F
Equilibrium distance
Electronegativity of elements
Interatomic bonds - ionic
Interatomic bonds - covalent
Interatomic bonds – metallic
Implication of bond type to toughness/fragility of materials
Molecular bonds – hydrogen bonds
Molecular bonds – van der Waals forces
graphite
Material classes - summaryProperty Ceramics Metals Polymers
Hardness High Medium-high Low
Stiffness (Young’smodulus of elasticity)
high Medium-high low
Strength High, but brittle High and ductile Low strength, high ductility
Thermal expansion Low High High
Ductility Low High High
Wear resistance High Low-medium Low
Metals Ceramics and glass Polymers
Good conductors ofelectricity and heat
Electrical and thermal insulators(at the same timesemiconductors and superconductors)
Electrical and thermal insulators
Strong and ductile Hard, fragile, non-ductile Soft, low strength, highly deformable
Nontransparent Some transparent Some transparent
Prone to corrosion damage Corrosion resistant, resistant against aggresive chemical compounds
Corrosion resistant
High density Medium density Low density
Iron, steel, Cu, Al, brass SiC, WC, Al2O3, NaCl,… Polymers, rubbers, …
Material classes - summary
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