chapter 8. deformation and strengthening...
TRANSCRIPT
![Page 1: Chapter 8. Deformation and Strengthening Mechanismshome.skku.edu/~femlab/lecture/introduction_mse/lecture17.pdfDeformation Mechanisms for Ceramic Materials 8.15 Crystalline Ceramics](https://reader031.vdocuments.mx/reader031/viewer/2022021611/5e5ad7463ea8145a487d2545/html5/thumbnails/1.jpg)
Chapter 8. Deformation and Strengthening Mechanisms
• Recovery, Recrystallization and Grain Growth• Deformation Mechanisms for Ceramic MaterialsM h i f D f ti d f St th i f P l• Mechanisms of Deformation and for Strengthening of Polymers
![Page 2: Chapter 8. Deformation and Strengthening Mechanismshome.skku.edu/~femlab/lecture/introduction_mse/lecture17.pdfDeformation Mechanisms for Ceramic Materials 8.15 Crystalline Ceramics](https://reader031.vdocuments.mx/reader031/viewer/2022021611/5e5ad7463ea8145a487d2545/html5/thumbnails/2.jpg)
Recovery, Recrystallization and Grain Growth
8.12 Recovery
Some of the stored internal strain energy is relieved by virtue of dislocation
Motion, as a result of enhanced atomic diffusion at the elevated temperature
8.13 Recrystallization
The formation of a new set of strain-free and equiaxed grains that have low
dislocation densities and are characteristic of the precold-Worked condition.
The driving force – the difference in internal E between the strained and
unstrained materials.
![Page 3: Chapter 8. Deformation and Strengthening Mechanismshome.skku.edu/~femlab/lecture/introduction_mse/lecture17.pdfDeformation Mechanisms for Ceramic Materials 8.15 Crystalline Ceramics](https://reader031.vdocuments.mx/reader031/viewer/2022021611/5e5ad7463ea8145a487d2545/html5/thumbnails/3.jpg)
![Page 4: Chapter 8. Deformation and Strengthening Mechanismshome.skku.edu/~femlab/lecture/introduction_mse/lecture17.pdfDeformation Mechanisms for Ceramic Materials 8.15 Crystalline Ceramics](https://reader031.vdocuments.mx/reader031/viewer/2022021611/5e5ad7463ea8145a487d2545/html5/thumbnails/4.jpg)
![Page 5: Chapter 8. Deformation and Strengthening Mechanismshome.skku.edu/~femlab/lecture/introduction_mse/lecture17.pdfDeformation Mechanisms for Ceramic Materials 8.15 Crystalline Ceramics](https://reader031.vdocuments.mx/reader031/viewer/2022021611/5e5ad7463ea8145a487d2545/html5/thumbnails/5.jpg)
8.14 Grain Growth
![Page 6: Chapter 8. Deformation and Strengthening Mechanismshome.skku.edu/~femlab/lecture/introduction_mse/lecture17.pdfDeformation Mechanisms for Ceramic Materials 8.15 Crystalline Ceramics](https://reader031.vdocuments.mx/reader031/viewer/2022021611/5e5ad7463ea8145a487d2545/html5/thumbnails/6.jpg)
Deformation Mechanisms for Ceramic Materials
8.15 Crystalline Ceramics
Plastic deformations, as with metals, by the motion of dislocations. y
But, there are very few slip systems
8.16 Noncrystalline Ceramics8.16 Noncrystalline Ceramics
Plastic deformations does not occur by the motion of dislocations.
Rather, these materials deform by viscous flow, the same manner in liquids.
![Page 7: Chapter 8. Deformation and Strengthening Mechanismshome.skku.edu/~femlab/lecture/introduction_mse/lecture17.pdfDeformation Mechanisms for Ceramic Materials 8.15 Crystalline Ceramics](https://reader031.vdocuments.mx/reader031/viewer/2022021611/5e5ad7463ea8145a487d2545/html5/thumbnails/7.jpg)
Mechanisms of Deformation and for Strengthening of Polymers
8.17 Deformation of semicrystalline polymers
h i f l i f i• Mechanism of Elastic Deformation
• Mechanism of Plastic Deformation
![Page 8: Chapter 8. Deformation and Strengthening Mechanismshome.skku.edu/~femlab/lecture/introduction_mse/lecture17.pdfDeformation Mechanisms for Ceramic Materials 8.15 Crystalline Ceramics](https://reader031.vdocuments.mx/reader031/viewer/2022021611/5e5ad7463ea8145a487d2545/html5/thumbnails/8.jpg)
8.18 Factors that influence the mechanical properties of
semicrystalline polymerssemicrystalline polymers
• Molecular Weight
• Degree of crystallinity
nMATSTS −= ∞
• Degree of crystallinity
• Predeformation by drawingy g
• Heat Teating
![Page 9: Chapter 8. Deformation and Strengthening Mechanismshome.skku.edu/~femlab/lecture/introduction_mse/lecture17.pdfDeformation Mechanisms for Ceramic Materials 8.15 Crystalline Ceramics](https://reader031.vdocuments.mx/reader031/viewer/2022021611/5e5ad7463ea8145a487d2545/html5/thumbnails/9.jpg)
8.19 Deformation of elastomers
• Vulcanization
![Page 10: Chapter 8. Deformation and Strengthening Mechanismshome.skku.edu/~femlab/lecture/introduction_mse/lecture17.pdfDeformation Mechanisms for Ceramic Materials 8.15 Crystalline Ceramics](https://reader031.vdocuments.mx/reader031/viewer/2022021611/5e5ad7463ea8145a487d2545/html5/thumbnails/10.jpg)
Chapter 9. Failure
• FractureF ti• Fatigue
• Creep
![Page 11: Chapter 8. Deformation and Strengthening Mechanismshome.skku.edu/~femlab/lecture/introduction_mse/lecture17.pdfDeformation Mechanisms for Ceramic Materials 8.15 Crystalline Ceramics](https://reader031.vdocuments.mx/reader031/viewer/2022021611/5e5ad7463ea8145a487d2545/html5/thumbnails/11.jpg)
Fracture
9.2 Fundamentals of fracture
Two steps – crack formation, propagation
• Ductile • Brittle
![Page 12: Chapter 8. Deformation and Strengthening Mechanismshome.skku.edu/~femlab/lecture/introduction_mse/lecture17.pdfDeformation Mechanisms for Ceramic Materials 8.15 Crystalline Ceramics](https://reader031.vdocuments.mx/reader031/viewer/2022021611/5e5ad7463ea8145a487d2545/html5/thumbnails/12.jpg)
![Page 13: Chapter 8. Deformation and Strengthening Mechanismshome.skku.edu/~femlab/lecture/introduction_mse/lecture17.pdfDeformation Mechanisms for Ceramic Materials 8.15 Crystalline Ceramics](https://reader031.vdocuments.mx/reader031/viewer/2022021611/5e5ad7463ea8145a487d2545/html5/thumbnails/13.jpg)
9.5 Principles of fracture Mechanics
Stress concentration
⎥⎥⎤
⎢⎢⎡
⎟⎟⎠
⎞⎜⎜⎝
⎛+=
2/1
21omaσσ
⎥⎦⎢⎣⎟⎠
⎜⎝ t
om ρ
2/1
2 ⎟⎟⎞
⎜⎜⎛ a2 ⎟⎟
⎠⎜⎜⎝
=t
om ρσσ
Stress concentration factor K
2/1
2 ⎟⎟⎞
⎜⎜⎛
== m aK σ
Stress concentration factor, Kt
2 ⎟⎟⎠
⎜⎜⎝ to
tKρσ
![Page 14: Chapter 8. Deformation and Strengthening Mechanismshome.skku.edu/~femlab/lecture/introduction_mse/lecture17.pdfDeformation Mechanisms for Ceramic Materials 8.15 Crystalline Ceramics](https://reader031.vdocuments.mx/reader031/viewer/2022021611/5e5ad7463ea8145a487d2545/html5/thumbnails/14.jpg)
![Page 15: Chapter 8. Deformation and Strengthening Mechanismshome.skku.edu/~femlab/lecture/introduction_mse/lecture17.pdfDeformation Mechanisms for Ceramic Materials 8.15 Crystalline Ceramics](https://reader031.vdocuments.mx/reader031/viewer/2022021611/5e5ad7463ea8145a487d2545/html5/thumbnails/15.jpg)
Stress analysis of cracks
)(2
θπ
σ xx fr
K=
)(2
θπ
σ yy fr
K=
)(θfK )(2
θπ
τ xyxy fr
=
aYK πσ=Stress intensity factor K aYK πσ=Stress intensity factor, K
![Page 16: Chapter 8. Deformation and Strengthening Mechanismshome.skku.edu/~femlab/lecture/introduction_mse/lecture17.pdfDeformation Mechanisms for Ceramic Materials 8.15 Crystalline Ceramics](https://reader031.vdocuments.mx/reader031/viewer/2022021611/5e5ad7463ea8145a487d2545/html5/thumbnails/16.jpg)
Fracture toughness, Kc
aWaYK πσ)/(= aWaYK CC πσ)/(=
Plane fracture toughness, KIC
aYKIC πσ=
![Page 17: Chapter 8. Deformation and Strengthening Mechanismshome.skku.edu/~femlab/lecture/introduction_mse/lecture17.pdfDeformation Mechanisms for Ceramic Materials 8.15 Crystalline Ceramics](https://reader031.vdocuments.mx/reader031/viewer/2022021611/5e5ad7463ea8145a487d2545/html5/thumbnails/17.jpg)
9.8 Impact fracture testing
![Page 18: Chapter 8. Deformation and Strengthening Mechanismshome.skku.edu/~femlab/lecture/introduction_mse/lecture17.pdfDeformation Mechanisms for Ceramic Materials 8.15 Crystalline Ceramics](https://reader031.vdocuments.mx/reader031/viewer/2022021611/5e5ad7463ea8145a487d2545/html5/thumbnails/18.jpg)
Ductile-to-Brittle Transition