Question

Assertion: The materials which have a very small range of plastic extension are called brittle materials.
Reason: If the stress is increased beyond the elastic limit, the material will break.
A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
B. Both Assertion and Reason are true and Reason is not the correct explanation of Assertion.
C. Assertion is true but the reason is false.
D. Both Assertion and Reason are false.

Answer 1

Hint : The elastic limit of a material is the maximum stress that may be applied without inducing plastic (permanent) deformation.
When a material is stressed below its elastic limit, it returns to its original length when the tension is removed.
The ability of a solid substance to undergo a non-reversible change of shape in response to applied forces is known as plastic deformation or extension.
The transition from elastic to plastic behavior is referred to as yielding in engineering.

Complete step-by-step solution:
Brittle materials are ones that break when a tiny force is applied above their elastic limit. However, the material does not have to fail after reaching its elastic limit, which is a feature of ductile materials.
After the material is subjected to the action of a force, it will not fail, but it will not recover completely, resulting in a persistent distortion when the force is removed.
Stresses develop beyond the proportionate limit as the test item is subjected to greater quantities of tensile force. Hooke's law does not apply to the stress-strain relationship. If the load is larger than the yield strength, undesired plastic will develop.

Note: Metals can break down into ductile or brittle fragments. The ductile fracture occurs when a metal can withstand a significant amount of plastic strain or distortion before fracturing. Near the fracture faces, a considerable portion of the plastic flow is usually concentrated.
This module's main topic is brittle cleavage fracture. Brittle cleavage fracture occurs when a material has a high strain-hardening rate but low cleavage strength or is extremely sensitive to multi-axial stress.