A test specimen is stressed slightly beyond the yield point and then unloaded. Its yield strength (a) Decreases (b) Increases (c) Remains same (d) Become equal to UTS (Explain clearly)

The yield strength of a material is the stress required to produce a small specified amount of plastic deformation.

The yield strength obtained by an offset method is commonly used for engineering purposes because it avoids the practical difficulties of determining the exact point at which plastic deformation begins to occur.

When a test specimen is stressed slightly beyond the yield point and then unloaded, it undergoes permanent plastic deformation. This means that the material will not return to its original, unstressed condition when the load is removed. Therefore, the yield strength of the material will not decrease after unloading. Instead, it may become slightly higher due to strain hardening, but it will not increase to the ultimate tensile strength (UTS) because the material has not been subjected to further deformation beyond the yield point

Therefore, the correct answer is (c or b ) the yield strength remains the same or slightly increases after unloading.