부산대학교 재료공학부 계면공학 연구실 [Mechanical Properties]  Mechanical Properties: mechanical properties of a material are those properties that involve a reaction to an applied load.  Wear Chap. 3. Mechanical Properties

부산대학교 재료공학부 계면공학 연구실  Deformation: in materials science, deformation refers to any changes in the shape or size of an object due to an applied force or a change in temperature.materials science force The first case can be a result of tensile (pulling) forces, compressive (pushing) forces, shear, bending or torsion (twisting).tensile compressiveshearbendingtorsion In the second case, which is determined by the temperature, is the mobility of the structural defects such as grain boundaries, point vacancies, line and screw dislocations, stacking faults and twins in both crystalline and non-crystalline solids. The movement or displacement of such mobile defects is thermally activated, and thus limited by the rate of atomic diffusion. [deformation in metals] Chap. 3. Mechanical Properties

부산대학교 재료공학부 계면공학 연구실  Plastic deformation is a change of the material dimensions remaining after removal of the load caused the deformation.  Plastic deformations in metals occurs by “slip” mechanism. Strain [elongation per length] Stress [load per area] [deformation in metals] Strain gauge Gauge length Chap. 3. Mechanical Properties

부산대학교 재료공학부 계면공학 연구실  Tensile testing, also known as tension testing, is a fundamental materials science test in which a sample is subjected to a controlled tension until failure.materials sciencetension [deformation in metals] SlipTwin Chap. 3. Mechanical Properties

부산대학교 재료공학부 계면공학 연구실 [deformation in metals] Chap. 3. Mechanical Properties

부산대학교 재료공학부 계면공학 연구실  Elongation(  ) : the state of being elongated or lengthened; also : the process of growing or increasing in length. Elastic deformation [deformation in metals] Chap. 3. Mechanical Properties

부산대학교 재료공학부 계면공학 연구실 Plastic deformation  Plastic deformation : occurrence of permanent deformation Slip and slip system? [deformation in metals] Chap. 3. Mechanical Properties

부산대학교 재료공학부 계면공학 연구실  Plastic deformation in metals: related to the slip of atoms over atoms like following the figure. [deformation in metals] Chap. 3. Mechanical Properties

부산대학교 재료공학부 계면공학 연구실  Slip system: set of [slip plane + slip direction] in the metals.  closed packed planes and directions. [deformation in metals] The required force for slip? [FCC] [BCC] Point: D 가 짧을수록 d 가 클수록 소성변형이 용이함. Chap. 3. Mechanical Properties

부산대학교 재료공학부 계면공학 연구실  Number of slip system is important factor affecting slip [deformation in metals] [BCC] [FCC] Chap. 3. Mechanical Properties

부산대학교 재료공학부 계면공학 연구실 [deformation in metals]  Deformation mechanism in the metals: slip / twin slip twin Chap. 3. Mechanical Properties

부산대학교 재료공학부 계면공학 연구실 [deformation in metals] slip twin Chap. 3. Mechanical Properties

부산대학교 재료공학부 계면공학 연구실 [deformation in metals]  Absorbing energy: resilience and toughness Chap. 3. Mechanical Properties

부산대학교 재료공학부 계면공학 연구실 [deformation in metals] Change in microstructure  How about microstructure after plastic deformation in the metal Chap. 3. Mechanical Properties

부산대학교 재료공학부 계면공학 연구실 [Ceramics] [deformation in Ceramics]  How about deformation mechanisms in the Ceramics Chap. 3. Mechanical Properties

부산대학교 재료공학부 계면공학 연구실 [deformation in Polymers]  How about deformation mechanisms in the Polymers Chap. 3. Mechanical Properties

부산대학교 재료공학부 계면공학 연구실 [deformation in Indentation]  How about deformation mechanisms in the indentation indenter Chap. 3. Mechanical Properties

부산대학교 재료공학부 계면공학 연구실 [Homework #3] / Due date: before next class 1. Describe plastic deformation behavior in FCC, BCC and HCP. 2. Define importance of slip system in plastic deformation. 3. Describe behavior of tensile testing in Ceramics. 4. Describe behavior of tensile testing in Polymers. 5. Compare properties of hardness and toughness in materials. Chap. 3. Mechanical Properties