Question

In crystalline materials, the plastic deformation occurs when the group of atoms or molecules slides past each other.

(a) True

(b) False

I got this question during a job interview.

Question is taken from Plastic Deformation and Yield Criteria in chapter Types of Die & Metal Forming Processes of Casting-Forming-Welding II

Answer 1

Correct answer is (b) False

Best explanation: Material always shows a non-recoverable deformation when it is subjected to stresses beyond certain minimum stress. Crystalline materials experience permanent deformation when slipping occurs along the definite crystalline planes. But in amorphous materials, permanent deformation occurs when the group of atoms or molecules slides past each other.