When the number of cycles reaches 600 000,an e-shaped spring rod made of 60Si2Mn breaks in the fa-tigue test.In order to find out the cause of break,the morphology,energy spectrum,metallographic organization,hard-ness and chemical composition of the e-shaped spring rod at the place of break are analyzed.Analysis results show that:due to there are pulling grooves and inclusions on the surface of the raw material of the spring rods,in the fatigue test process by the role of high stress alternating load,stress concentration is produced at the grooves of the spring rods,and microcracks is gradually formed.At the same time,tempered martensite is presented which leads to disloca-tion pile-up during the deformation process and the formation of a high stress zone.This accelerates the crack expan-sion and eventually leads to the fracture of the spring rod in a relatively short time.
Metro Linee-shaped Spring RodFatigue FracturePhysical and Chemical Test
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