Q1: Fatigue limit improvement by over stressing the metal by successively increasing the load is called coaxing. In fatigue failure, the material fails

ANS:A - below the yield point.

In fatigue failure, the material fails below the yield point. Explanation: Fatigue failure occurs when a material fails due to repeated cyclic loading, even though the stress levels applied are below the material's ultimate tensile strength. This type of failure is characterized by crack initiation and propagation, leading to fracture. When a material is subjected to cyclic loading, the stress applied to the material fluctuates between maximum and minimum values. Over time, the repeated cyclic loading causes microscopic cracks to form and grow within the material, eventually leading to catastrophic failure. Fatigue failure typically occurs at stress levels significantly lower than the material's ultimate tensile strength. Therefore, it occurs below the yield point, which is the point at which plastic deformation begins in the material. The material may still be in the elastic deformation range when fatigue failure occurs. Coaxing, as mentioned in the question, refers to the process of improving the fatigue limit of a material by subjecting it to successive overloading cycles. This process can help to compress surface defects and improve the material's resistance to fatigue failure. However, even with coaxing, fatigue failure still occurs below the yield point of the material. Therefore, in fatigue failure, the material fails below the yield point.