Cause analysis for cracking formation in frame riser of motorcycle
The motorcycle's frame riser made by 20# seamless steel tube was cracked during use.The cause was investiga-ted through metallographic examination,chemical composition analysis,hardness test and scanning electron microscope.The results showed that the chemical composition of frame riser could meet the requirements of national standards,and there was no abnormality in the hardness and microstructure.Martensite was found in the welding heat affected zone of test-ed surface.The existence of martensite increased the brittleness and reduced the toughness of riser support.The hardness difference between martensitic structure and matrix structure formed stress concentration.Therefore,the main reason to cause cracking of frame riser was the martensite which was generated during welding.
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维普
