InterviewSolution
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InterviewSolution
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While Normal Carburising And Nitriding Surface Treatments Increase Fatigue Strength, Excessive Treatment May Decrease The Fatigue Strength. Why ? |
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Answer» Normal carburising/nitriding treatments increase VOLUME due to phase TRANSFORMATION at Surface and introduce residual compressive surface stress and THUS increase the fatigue strength. By excessive treatment the high compressive STRESSES are introduced but these are balanced by high in¬ternal tensile stresses of equal value and the SUBSURFACE fatigue cracks may develop in the regions of high tensile stress and lead to early fatigue failure. Normal carburising/nitriding treatments increase volume due to phase transformation at Surface and introduce residual compressive surface stress and thus increase the fatigue strength. By excessive treatment the high compressive stresses are introduced but these are balanced by high in¬ternal tensile stresses of equal value and the subsurface fatigue cracks may develop in the regions of high tensile stress and lead to early fatigue failure. |
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