汽车后扭力梁开裂问题分析

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Abstract：The failureanalysis was conducted onthe cracked rear torsion beam ofacertain vehicle model after fatigue durability test byusing direct-reading spectrometer，hardness tester，scanning electron microscope and metallographic microscope.The chemical composition and hardness meet the material standards and technical requirements of the drawings.The results offracture and metallographic inspection show that the failure mode of the rear torsion beam is stress corrosion cracking originating from the inner wall.The main reason is that the poor anticorrosion treatment of the iner wallof the rear torsion beamcauses corrosion，resulting in stress corrosion cracking and expansion of the rear torsion beam with high-strength tisse sensitivity under the tensile stress of the fatigue strength test.The fatigue durabilitytest was carriedout with the rear torsion beam assembly without corrosion on the inner wall， and no cracking problem was found.

Keywords： rear torsion beam; fatigue endurance test; corrosion pit; stress corrosion cracking

1序言

扭力梁式后悬架系统，具有结构简单、占用空间小、成本较低，以及装配维修便利等优点，在A/A0级乘用车上广泛应用[1，2]。（剩余3319字）