Improvements in a plastic working process for face-centered cubic metals, and titanium and zirconium having close-packed-hexagonal lattice, which process utilizes a phenomenon that the ductility of these metals is increased at sub-zero temperatures, i.e., temperatures below 0.degree. C. This process includes the steps of (i) imparting plastic flow including at least a uniaxial tensile stress field a metal at a temperature below zero, (ii) subjecting the metal to plastic flow to an extent that the strain of the metal is within the limit of uniform elongation of the metal, and then to plastic flow including at least a uniaxial tensile stress field continuously thereafter, or (iii) using frost as a lubricant for plastic working at temperatures below 0.degree. C according to either one of the foregoing steps.

Thermal regulation of a coated work-piece during the reconfiguration of the work-piece is provided. One method embodying the invention comprises placing an externally coated reconfigurable work-piece, whose hardness has been temporarily modified to resist damage during the reconfiguration of the work-piece, into a reconfiguration chamber of a reconfiguration apparatus and reconfiguring the work-piece from a first configuration to a second configuration via physical communication between the external coating of the reconfigurable work-piece and the reconfiguration apparatus.

Apparatus for configuring an externally coated workpiece are provided. In one example, the apparatus includes a tubular reconfiguration chamber having a plurality of slidably mounted outer walls, the outer walls slidably mounted along individual radial lines emanating from and orthogonal to the central longitudinal axis of the tubular reconfiguration chamber; and a device for adjusting and maintaining the temperature of the external coating of a work-piece located within the tubular reconfiguration chamber. In another example the apparatus includes a reconfiguration chamber; a nozzle in fluid communication with the reconfiguration chamber, a regulator in fluid communication with the nozzle, the regulator adapted to regulate the flow of a thermal transfer fluid exiting the nozzle, and a controller in communication with the regulator, the controller adapted to send control signals to the regulator to maintain the surface temperature of the external coating of the reconfigurable work-piece within a predetermined temperature range, the predetermined temperature range associated with a predetermined minimum hardness of the external coating of the reconfigurable work-piece.

A method of impulse treatment which modifies at least one specified property of a material or object (such as a welded joint), or produces a material or object with at least one specified physical, mechanical or structural property, by adaptively controlling an impulse action upon the material/object is described. An impulse action includes normalized impulses and pauses, i.e., a controlled and adaptive alternation of periods of material condition impulse activation with periods of relaxation therebetween, wherein the pauses allow the material to recover from the impulse before the next impulse is applied to the material. The energy of the impulse actions can originate from various sources, but the method of the invention is in particular advantageous when the energy of action is initiated and delivered by ultrasonic impact, wherein the energy is applied to any suitable material so that at least one property of the material is modified or produced in order to attain a desired technical effect.

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.