Ultrasonic impact methods for treatment of welded structures

• US 20050092397A1
• Filed: 12/01/2004
• Published: 05/05/2005
• Est. Priority Date: 09/03/1998
• Status: Active Grant

• Current Assignee: Progress Rail Services Corporation (Caterpillar Incorporated)
• Original Assignee: Underground Imaging Technologies LLC
• Inventors: Statnikov, Efim S.
• Granted Patent: US 7,344,609 B2
• Time in Patent Office: Days
• US Class Current: 148/400
• CPC Class Codes: B23K 13/00 Welding by high-frequency current heating
• CPC Class Codes: B23K 9/32 Accessories earthing connections H01R
• CPC Class Codes: B23P 9/04 Treating or finishing by hammering or applying repeated pressure
• CPC Class Codes: C21D 10/00 Modifying the physical properties by methods other than heat treatment or deformation
• CPC Class Codes: C21D 2201/00 Treatment for obtaining particular effects
• CPC Class Codes: C21D 7/04 of the surface
• CPC Class Codes: C21D 9/50 for welded joints
• CPC Class Codes: Y10T 29/49774 by vibratory or oscillatory movement
• CPC Class Codes: Y10T 29/53535 including means to vibrate work

Abstract

This invention provides methods of treatment for work products of materials such as steel, bronze, plastic, etc. and particularly welded steel bodies by pulse impact energy, preferably ultrasonic, to relax fatigue and aging and extend expectant life. The treatment may occur (a) at original production, (b) during the active life period for maintenance or (c) after failure in a repair stage. The ultrasonic treatment improves the work product strength. In welded products residual stress patterns near the weld sites are relaxed and micro-stress defects such as voids and unusual grain boundaries are reduced. The basic method steps are non-destructive in nature, inducing interior pulse compression waves with ultrasonic transducers and accessory tools impacting an external product surface with enough impulse energy to heat and temporarily plasticize the metal interior and relax stresses. The nature of the work product interior structure being treated is determined by sensing the mechanical movement at the impact surface of the work body to produce feedback frequency and phase signals responsive to input impact signals. These signals automatically conform driving pulse energy frequency and phase to the input transducers to match the mechanical resonance frequency of the working transducers and increase efficiency of energy transfer. Such feedback signals also are available for automated procedures which can improve product quality and consistency.

Claims

1. -44. (canceled)

45. A load bearing work product body of a solid structural material having an interior structural zone having been reworked in a molten state induced by ultrasonically reproduced repetitive mechanical impulse impacts on an exterior work product body surface to form relaxed residual stress patterns and reformed grain boundary structure.

46. The work product body of claim 45 exhibiting a white layer in said zone.

47. (canceled)

48. (canceled)

49. (canceled)

50. A product body with an internal body structure established by treating the structure to improve life and load bearing strength therein comprising

applying to an external surface area in the vicinity of stress concentration regions of said structure by an impulse producing instrument in mechanical contact with the external surface a multiplicity of shock pulses of a magnitude and sequential relationship to induce temperatures to a predetermined depth in the structure, for inducing internal compression waves in a dynamic treatment zone of molten material,

inducing by reaction to said shock pulses in said dynamic treatment zone a compression wave pattern gradient of greater magnitude at a surface area than at remote locations in the product body, and

withdrawing the shock pulses in a manner that substantially cools the treatment zone to establish reconstructed compression wave distribution patterns thereby producing the internal body structure with higher fatigue strength and load bearing capacity.