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Consider the following statements for ductile fracture: 1. The material undergoes substantial plastic deformation with high energy absorption before fracture. 2. Presence of cracks on the surface of material initiates this type of failure. 3. Fracture occurs due to necking. Which of the above statements is/are correct? 

Consider the following statements for ductile fracture: 1. The material undergoes substantial plastic deformation with high energy absorption before fracture. 2. Presence of cracks on the surface of material initiates this type of failure. 3. Fracture occurs due to necking. Which of the above statements is/are correct?  Correct Answer 1 and 3 only

Explanation:

Ductile Fracture:

  • Most ductile metals fracture preceded by a moderate amount of necking, followed by the formation of voids, cracks and finally shear. Hence we can say that ductile fracture takes place after necking with little sound.
  • This gives a characteristic cup-and-cone fracture. In this central interior region has an irregular and fibrous appearance, which signifies plastic deformation.
  • Different progressive stages of ductile fracture are shown in figure.
  • As the cross-sectional areas is getting reduced at subsequent stages high energy is absorbed before fracture happens.

Additional InformationBrittle Fracture:

  • The brittle fracture that takes place with little or no preceding plastic deformation. It occurs, often at unpredictable levels of stress, by rapid crack propagation.
  • The direction of crack propagation is very nearly perpendicular to the direction of applied tensile stress. This fracture is also said to be trans granular because crack propagates through grains.
  • Thus, it has a grainy or faceted texture.
  • Most brittle fractures occur in a transgranular manner. However, the brittle fracture can occur in an intergranular manner i.e. crack propagates along grain boundaries.

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