In material testing, what does exceeding the fatigue limit lead to?

Exceeding the fatigue limit of a material directly leads to fatigue failure over time. The fatigue limit, also known as the endurance limit, is the maximum stress level a material can withstand for an infinite number of cycles without experiencing failure. When the stress applied to the material exceeds this limit, even if it's below the material's ultimate tensile strength, the material becomes susceptible to cumulative damage. This damage can lead to the formation of cracks, which can grow and eventually cause the material to fail under repeated loading and unloading cycles.

In contrast, other options like increased tensile strength, no effect on the material, or improved material performance do not accurately reflect the consequences of exceeding the fatigue limit. Increased tensile strength refers to the maximum amount of tensile stress that a material can withstand before failure, which isn't inherently improved simply by pushing beyond fatigue limits. "No effect on the material" is misleading, as exceeding the fatigue limit definitely affects the material negatively by promoting fatigue failure. Lastly, improved material performance contradicts the nature of fatigue limits, as higher stress levels beyond this threshold degrade the material's performance over time.