Which manufacturing process serves to extend the fatigue life span of mechanical parts?
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Answer: B. shot-peening
Explanation
Shot-peening bombards metallic surfaces with high-velocity steel shot media particles. This cold-working process induces beneficial residual compressive stresses in the outer surface layer. Compressive surface stresses effectively arrest microscopic fatigue crack propagation and extend component life. Fatigue failures typically initiate at microscopic surface tensile stress concentrations during cyclic loading. Surface treatment techniques modify outer material layers to improve mechanical durability and wear resistance. Residual stresses counteract applied tensile loads reducing the effective cyclic stress range experienced.
Aerospace turbine blades and automotive connecting rods undergo shot-peening to prevent fatigue failures. High-stress metal springs are routinely peened to enhance operational reliability and longevity. Manufacturing engineers use this surface enhancement to improve structural performance without adding weight. Finishing and polishing remove surface scratch defects but do not induce deep compressive stress layers. Decarburisation removes surface carbon which actually weakens steel and reduces its fatigue strength. Electroplating can introduce tensile residual stresses and hydrogen embrittlement if not carefully controlled.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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