ANS:B - Bauschinger effect.

The behavior of a metal specimen, where its yield stress in compression decreases after it has been plastically strained in tension, and vice versa, is termed the Bauschinger effect. The Bauschinger effect describes the phenomenon where the yield stress of a material changes depending on the direction of the applied stress and the history of plastic deformation. When a metal specimen is plastically deformed, dislocations within the material rearrange and interact in a way that affects subsequent deformation behavior. In the case of the Bauschinger effect, plastic deformation in tension relieves some of the internal stresses within the material, resulting in a decrease in yield stress in compression, and vice versa. The other options provided do not describe this specific phenomenon:

• Work hardening refers to the increase in yield strength that occurs when a material is plastically deformed.
• Creeping effect refers to the time-dependent deformation of a material under constant load or stress at elevated temperatures.
• Stress recovery effect is not a recognized term in materials science and engineering.