Q. For proper stretching operation, the metal sheet should be stressed above its yield strength.
✅ Correct Answer: (A)
true
Explanation: in stretch forming, a metal sheet is stretched by the help of stretcher machines. for proper and complete stretching of sheet, the material is deformed plastically which is also called as permanent deformation. the metal sheet is stressed above its yield strength for successfully achieving the plastic deformation of the metal sheet.