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6. Mechanical Properties. Forms of Mechanical Loading. compression. tension. shear. torsion. 6. Mechanical Properties. Stress-Strain Behaviour Linearelastic Deformation. Robert Hooke:. 6. Mechanical Properties. Stress-Strain Behaviour Nonlinearelastic Deformation.
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6. Mechanical Properties Forms of Mechanical Loading compression tension shear torsion
6. Mechanical Properties Stress-Strain Behaviour Linearelastic Deformation Robert Hooke:
6. Mechanical Properties Stress-Strain Behaviour Nonlinearelastic Deformation
6. Mechanical Properties Force-Separation-Curve
Potentielle Energie Anziehungskräfte Kraft K Anz-k. K-abst. Kernabstand Abs-k. Abstoßungskräfte 6. Mechanical Properties
6. Mechanical Properties Influence of Temperature
6. Mechanical Properties Tensile Properties of Metals(1) Streck- grenzen- effekt Lüders-Dehnung cV - Konz. gleitfähiger Versetzg b – Burgersvektor V - Abgleitgschwindigkeit
6. Mechanical Properties Deformation Mechanisms for Metals Basic Concepts of Dislocations(3) Video Versetzungsbewegung (Blasenmodell)
6. Mechanical Properties Deformation Mechanisms for Metals Characteristics of Dislocations(1)
6. Mechanical Properties Tensile Properties of Metals(3)
6. Mechanical Properties Deformation Mechanisms for Metals Basic Concepts of Dislocations(1)
6. Mechanical Properties Deformation Mechanisms for Metals Basic Concepts of Dislocations(2)
6. Mechanical Properties Deformation Mechanisms for Metals Basic Concepts of Dislocations(3) Video Versetzungsbewegung (Blasenmodell)
6. Mechanical Properties Effect of Temperature
6. Mechanical Properties Tensile Properties of Metals(2)
6. Mechanical Properties True Stress-Strain-Curve
6. Mechanical Properties Mechanical Behaviour of Ceramics(1)
6. Mechanical Properties Mechanical Behaviour of Ceramics(2)
6. Mechanical Properties Mechanical Behaviour of Polymers(1) spröde plastisch hoch elastisch C-C H-Brücken Van der Waals
6. Mechanical Properties Mechanical Behaviour of Polymers(2) Polymethylmetacrylate PMMA (Plexiglas) E-Modul sinkt mit steigender T Duktilität steigt mit steigender T
6. Mechanical Properties Tensile Properties of Metals(2)
6. Mechanical Properties Slip in Single Crystals Geometrical Relationships
6. Mechanical Properties Slip in Single Crystals Geometrical Relationships
6. Mechanical Properties Example Video Gleitlinienbildung
6. Mechanical Properties Slip Systems in the fcc-Lattice
6. Mechanical Properties Slip Systems in the bcc-Lattice(1)
6. Mechanical Properties Slip Systems in the bcc-Lattice(2)
6. Mechanical Properties Slip Systems in the bcc-Lattice(3)
6. Mechanical Properties Slip Systems in the hcp-Lattice(3) {1000}-[1120] →1 plane, 3 directions Only few possible slip systems! {1010}-[1120] →3 planes, 1 direction {1011}-[1120] →6 planes, 1 direction
6. Mechanical Properties Slip Systems
6. Mechanical Properties Anwendung in TWIP-Stählen => Hohe Verformung + Festigkeit Deformation twinning Twin Matrix
Hochleistungswerkstoff Stahl – eine faszinierende Vielfalt Verformbarkeit Streckgrenze [MPa]
6. Mechanical Properties Deformation: Slip vs. Twinning
6. Mechanical Properties What is the maximum shear-stress ?
6. Mechanical Properties The shear-stress-law of Schmid Winkel zwischen Zug- und Gleitrichtung kristallographische Gleitebene definiert A Kristallographische Gleitrichtung definiert Fg Schmid-Faktor
6. Mechanical Properties Dislocation Sources - The Frank-Read Source ·b Critical radius:R=lo/2 lo: dislocation length
6. Mechanical Properties Plastic Deformation of Polycrystalline Materials (Cu)
6. Mechanical Properties Plastic Deformation of Polycrystalline Materials Requirement of five independent slip systems to realize any plastic deformation in polycrystals (Compatibility of deformation)
6. Mechanical Properties Plastic deformation: Single vs. polycrystal • Increase due to: • Manifold of grain orientations in polycrystals • Grain Boundaries!!! Why such an increase of strength?
6. Mechanical Properties Plastic deformation Characteristics of Dislocations
6. Mechanical Properties Plastic deformation Characteristics of Dislocations
6. Mechanical Properties Plastic Deformation of Polycrystalline Materials • Grains with the highest Schmid-factor deform first. • yield stress (= Streckgrenze) is reached when deformation of all grains occurs • any plastic deformation of polycrystalline materials needs activation of • 5 independent slip systems (Compatibility of deformation) The role of Grain size
6. Mechanical Properties The Relation of Hall-Petch
6. Mechanical Properties Solid solution hardening • Alloying causes hardening effects due to three types of interactions between the dislocations and the alloyed atoms: • Parelastic interaction distortion of the lattice; change in the lattice parameter a • Dielastic interaction different shear modulus G of alloyed atoms compared to that of the matrix atoms • chemical interaction
6. Mechanical Properties Work Hardening Property Degree of Deformation
6. Mechanical Properties Dispersion and precipitation hardening The Orowan-Mechanism The Fine-Kelly-Mechanism shear-modulus particle diameter surface energy Volume fraction of particles Burgers-vector particle distance
6. Mechanical Properties Texture hardening • Strengthening effect due to: • bad orientation between applied stress and „slip system“ • morphological texture (Hall-Petch!!) Loading in direction A shows an enhanced yield stresscompared to direction B B A
6. Mechanical Properties Mechanisms to enhance strength Plastic deformation - at lower temperatures (no recyrstallization) grain refinement – Hall Petch solid solution hardening – solubility and lattice distortion dispersion hardening – input of highly dispers particles precipitation hardening – creation of particles (solubility) texture hardening (morphology, orientation and slip systems,
