According to an aspect of the disclosure, there may be provided a peening apparatus for generating a compressive residual stress on a pipe member including at least one curved round portion and having a hollow inside formed therein in which a first fluid and a second fluid, which is in a gas phase, are accommodated, the apparatus including: a probe which is disposed such that it is submerged in the first fluid supplied to the hollow inside, and which is configured to apply a wave to the first fluid, wherein the first fluid and the second fluid have different acoustic impedances, so that the wave is totally reflected on a reflection surface where the first fluid and the second fluid are in contact, and forms a standing wave, and wherein a cavity generated and grown by the formed standing wave is exploded and emits a shock wave or microjet, which generates a compressive residual stress on the inner surface of the pipe member surrounding the hollow inside.

According to an aspect of the disclosure, there may be provided a peening apparatus for generating a compressive residual stress on a pipe member including at least one curved round portion and having a hollow inside formed therein in which a first fluid and a second fluid, which is in a gas phase, are accommodated, the apparatus including: a probe which is disposed such that it is submerged in the first fluid supplied to the hollow inside, and which is configured to apply a wave to the first fluid, wherein the first fluid and the second fluid have different acoustic impedances, so that the wave is totally reflected on a reflection surface where the first fluid and the second fluid are in contact, and forms a standing wave, and wherein a cavity generated and grown by the formed standing wave is exploded and emits a shock wave or microjet, which generates a compressive residual stress on the inner surface of the pipe member surrounding the hollow inside.

An apparatus for forming a metal workpiece having a first surface is described herein. The apparatus includes a trough containing a liquid. The apparatus also includes a support for positioning the metal workpiece in an impact-receiving position. In the impact-receiving position, the first surface is submerged in the liquid. The apparatus includes a driven member for applying multiple impacts to the first surface of the metal workpiece while the metal workpiece is in the impact-receiving position.

An apparatus for forming a metal workpiece having a first surface is described herein. The apparatus includes a trough containing a liquid. The apparatus also includes a support for positioning the metal workpiece in an impact-receiving position. In the impact-receiving position, the first surface is submerged in the liquid. The apparatus includes a driven member for applying multiple impacts to the first surface of the metal workpiece while the metal workpiece is in the impact-receiving position.

A water jet peening device includes a sealed vessel provided to cover a surface of a welded portion, and adapted to be in a sealed state where an internal pressure is higher than an outside, a jet nozzle adapted to jet high-pressure water to create a cavitation bubble toward the surface of the welded portion, inside the sealed vessel, and a pressure control hole adapted to be able to adjust the internal pressure of the sealed vessel. The water jet peening device can efficiently reform a tensile residual stress on the surface of the welded portion to a compressive residual stress.

A water jet peening device includes a sealed vessel provided to cover a surface of a welded portion, and adapted to be in a sealed state where an internal pressure is higher than an outside, a jet nozzle adapted to jet high-pressure water to create a cavitation bubble toward the surface of the welded portion, inside the sealed vessel, and a pressure control hole adapted to be able to adjust the internal pressure of the sealed vessel. The water jet peening device can efficiently reform a tensile residual stress on the surface of the welded portion to a compressive residual stress.

A device and method for continuously producing an at least partly hollow shaft having a varying inner diameter includes forging tools that are arranged centrally symmetrically about a forging axis and are driven radially, a clamping chuck for holding an at least partly hollow cylindrical blank, and a counter-holder for axially supporting the blank. The counter-holder has a base and a counter-holder mandrel arranged on the base and extending axially into a central cavity in the blank. The mandrel is formed of at least two parts, wherein a first part of the counter-holder mandrel constitutes an inner part and a second part of the counter-holder mandrel constitutes an outer part surrounding the inner part. At least the outer part can be moved axially relative to the inner part.

A device and method for continuously producing an at least partly hollow shaft having a varying inner diameter includes forging tools that are arranged centrally symmetrically about a forging axis and are driven radially, a clamping chuck for holding an at least partly hollow cylindrical blank, and a counter-holder for axially supporting the blank. The counter-holder has a base and a counter-holder mandrel arranged on the base and extending axially into a central cavity in the blank. The mandrel is formed of at least two parts, wherein a first part of the counter-holder mandrel constitutes an inner part and a second part of the counter-holder mandrel constitutes an outer part surrounding the inner part. At least the outer part can be moved axially relative to the inner part.

A fluid end having a longitudinal bore less than about 36 inches in diameter has an internal surface that is cold-worked to have compressive stresses of at least 15 ksi (103.42 MPa) beneath the metal surface up to about 40 mils (1.016 mm).

A fluid end having a longitudinal bore less than about 36 inches in diameter has an internal surface that is cold-worked to have compressive stresses of at least 15 ksi (103.42 MPa) beneath the metal surface up to about 40 mils (1.016 mm).