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WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 1 Chair of Functional Materials 6. Mechanical Properties Forms of Mechanical.

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Presentation on theme: "WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 1 Chair of Functional Materials 6. Mechanical Properties Forms of Mechanical."— Presentation transcript:

1 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 1 Chair of Functional Materials 6. Mechanical Properties Forms of Mechanical Loading tension compression sheartorsion

2 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 2 Chair of Functional Materials 6. Mechanical Properties Stress-Strain Behaviour Linearelastic Deformation Robert Hooke:

3 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 3 Chair of Functional Materials 6. Mechanical Properties Stress-Strain Behaviour Nonlinearelastic Deformation

4 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 4 Chair of Functional Materials 6. Mechanical Properties Force-Separation-Curve

5 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 5 Chair of Functional Materials Potentielle Energie Anziehungskräfte Abstoßungskräfte Kraft Kernabstand Abs-k. Anz-k. K K-abst. 6. Mechanical Properties

6 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 6 Chair of Functional Materials 6. Mechanical Properties Influence of Temperature

7 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 7 Chair of Functional Materials 6. Mechanical Properties Tensile Properties of Metals(1) c V - Konz. gleitfähiger Versetzg b – Burgersvektor V - Abgleitgschwindigkeit Lüders-Dehnung Streck- grenzen- effekt

8 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 8 Chair of Functional Materials 6. Mechanical Properties Deformation Mechanisms for Metals Basic Concepts of Dislocations(3) Video Versetzungsbewegung (Blasenmodell)

9 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 9 Chair of Functional Materials 6. Mechanical Properties Deformation Mechanisms for Metals Characteristics of Dislocations(1)

10 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 10 Chair of Functional Materials 6. Mechanical Properties Tensile Properties of Metals(3)

11 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 11 Chair of Functional Materials 6. Mechanical Properties

12 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 12 Chair of Functional Materials 6. Mechanical Properties

13 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 13 Chair of Functional Materials 6. Mechanical Properties Deformation Mechanisms for Metals Basic Concepts of Dislocations(1)

14 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 14 Chair of Functional Materials 6. Mechanical Properties Deformation Mechanisms for Metals Basic Concepts of Dislocations(2)

15 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 15 Chair of Functional Materials 6. Mechanical Properties Deformation Mechanisms for Metals Basic Concepts of Dislocations(3) Video Versetzungsbewegung (Blasenmodell)

16 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 16 Chair of Functional Materials 6. Mechanical Properties Effect of Temperature

17 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 17 Chair of Functional Materials 6. Mechanical Properties Tensile Properties of Metals(2)

18 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 18 Chair of Functional Materials 6. Mechanical Properties True Stress-Strain-Curve

19 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 19 Chair of Functional Materials 6. Mechanical Properties Mechanical Behaviour of Ceramics(1)

20 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 20 Chair of Functional Materials 6. Mechanical Properties Mechanical Behaviour of Ceramics(2)

21 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 21 Chair of Functional Materials 6. Mechanical Properties Mechanical Behaviour of Polymers(1) spröde plastisch hoch elastisch C-C H-Brücken Van der Waals

22 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 22 Chair of Functional Materials 6. Mechanical Properties Mechanical Behaviour of Polymers(2) Polymethylmetacrylate PMMA (Plexiglas) E-Modul sinkt mit steigender T Duktilität steigt mit steigender T

23 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 23 Chair of Functional Materials 6. Mechanical Properties Tensile Properties of Metals(2)

24 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 24 Chair of Functional Materials 6. Mechanical Properties Slip in Single Crystals Geometrical Relationships

25 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 25 Chair of Functional Materials 6. Mechanical Properties Slip in Single Crystals Geometrical Relationships

26 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 26 Chair of Functional Materials 6. Mechanical Properties Example Video Gleitlinienbildung

27 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 27 Chair of Functional Materials 6. Mechanical Properties Slip Systems in the fcc-Lattice

28 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 28 Chair of Functional Materials 6. Mechanical Properties Slip Systems in the bcc-Lattice(1)

29 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 29 Chair of Functional Materials 6. Mechanical Properties Slip Systems in the bcc-Lattice(2)

30 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 30 Chair of Functional Materials 6. Mechanical Properties Slip Systems in the bcc-Lattice(3)

31 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 31 Chair of Functional Materials 6. Mechanical Properties Slip Systems in the hcp-Lattice(3) {1000}-[1120] 1 plane, 3 directions {1010}-[1120] 3 planes, 1 direction {1011}-[1120] 6 planes, 1 direction Only few possible slip systems!

32 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 32 Chair of Functional Materials 6. Mechanical Properties Slip Systems

33 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 33 Chair of Functional Materials 6. Mechanical Properties Deformation twinning Twin Matrix Anwendung in TWIP-Stählen => Hohe Verformung + Festigkeit

34 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 34 Chair of Functional Materials Streckgrenze [MPa] Verformbarkeit Hochleistungswerkstoff Stahl – eine faszinierende Vielfalt

35 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 35 Chair of Functional Materials 6. Mechanical Properties SlipTwinning Atomic movement Lattice orientation Atoms move fractional atomic spacing. Microscopic appearance Thin linesWide bands or broad lines Lattice orientation No change in lattice orientation. The steps are only visible on the surface of the crystal and can be removed by polishing. After polishing there is no evidence of slip. Lattice orientation changes. Surface polishing will not destroy the evidence of twinning. Deformation: Slip vs. Twinning

36 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 36 Chair of Functional Materials 6. Mechanical Properties What is the maximum shear-stress ?

37 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 37 Chair of Functional Materials 6. Mechanical Properties The shear-stress-law of Schmid kristallographische Gleitebene definiert A Kristallographische Gleitrichtung definiert F g Schmid-Faktor Winkel zwischen Zug- und Gleitrichtung

38 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 38 Chair of Functional Materials 6. Mechanical Properties Dislocation Sources - The Frank-Read Source Critical radius: R=l o /2 l o : dislocation length ·b

39 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 39 Chair of Functional Materials 6. Mechanical Properties Plastic Deformation of Polycrystalline Materials (Cu)

40 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 40 Chair of Functional Materials 6. Mechanical Properties Plastic Deformation of Polycrystalline Materials Requirement of five independent slip systems to realize any plastic deformation in polycrystals (Compatibility of deformation)

41 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 41 Chair of Functional Materials 6. Mechanical Properties Plastic deformation: Single vs. polycrystal Why such an increase of strength? Increase due to: Manifold of grain orientations in polycrystals Grain Boundaries!!!

42 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 42 Chair of Functional Materials 6. Mechanical Properties Plastic deformation Characteristics of Dislocations

43 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 43 Chair of Functional Materials 6. Mechanical Properties Plastic deformation Characteristics of Dislocations

44 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 44 Chair of Functional Materials 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

45 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 45 Chair of Functional Materials The Relation of Hall-Petch 6. Mechanical Properties

46 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 46 Chair of Functional Materials 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

47 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 47 Chair of Functional Materials Work Hardening Property Degree of Deformation 6. Mechanical Properties

48 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 48 Chair of Functional Materials 6. Mechanical Properties The Fine-Kelly-Mechanism particle diameter surface energy Burgers-vector The Orowan-Mechanism shear-modulus particle distance Volume fraction of particles Dispersion and precipitation hardening

49 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 49 Chair of Functional Materials 6. Mechanical Properties Texture hardening Strengthening effect due to: bad orientation between applied stress and slip system morphological texture (Hall-Petch!!) A B Loading in direction A shows an enhanced yield stress compared to direction B

50 WS2012/13 | BSc – Introduction in Materials Science | Prof. Dr.-Ing. Frank Mücklich 50 Chair of Functional Materials Mechanisms to enhance strength 1. Plastic deformation - at lower temperatures (no recyrstallization) 2. grain refinement – Hall Petch 3. solid solution hardening – solubility and lattice distortion 4. dispersion hardening – input of highly dispers particles 5. precipitation hardening – creation of particles (solubility) 6. texture hardening (morphology, orientation and slip systems, 6. Mechanical Properties


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