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AssigneeNippon Steel Corporation
InventorsTetsuro Nose, Kiyotaka Nakashima
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The present invention provides a boom and arm member of a construction machine excellent in weld zone fatigue strength and a method of improvement of its fatigue strength, that is, a boom and arm member of a construction machine superior in weld zone fatigue strength, the boom and arm member of a construction machine characterized in that toes of full penetrated weld zones of the boom and arm member have vibration strike marks, and a method of improvement of its fatigue strength. Preferably, the residual stress of the bottom surface of the vibration strike marks is a 10 MPa or higher compressive residual stress.
A boom and arm member of a construction machine excellent in weld zone fatigue strength, said boom and arm member of construction machine characterized by having full penetrated weld zones and having vibration strike marks at toes of said full penetrated weld zones of said boom and arm member, wherein said vibration strike marks are formed by a vibration terminal made to vibrate in a vertical direction and a horizontal direction by different vibrators.
A method of improvement of boom and arm fatigue strength of a construction machine, said method of improvement of boom and arm member fatigue strength of a construction machine characterized by providing full penetrated weld zones in a boom and arm member of said construction machine, and applying vibration striking treatment by a vibration terminal made to vibrate in a vertical direction and a horizontal direction by different vibrators to toes of said full penetrated weld zones of said boom and arm member of said construction machine.
Dependencies are inferred from the claim text.