Abstract: A workpiece has a surface formed by a circular bore extending in the workpiece body along a bore axis. The bore surface includes a heat-affected zone pattern thereon, produced with a laser light beam. The heat-affected zone pattern can be a variety of patterns including a single helix, overlapping helixes a single annular ring and a plurality of annular rings. The heat-affected zones can have a variety of widths, as measured in relation to the longitudinal bore axis.

Abstract: A a method for laser heating a surface formed by a circular bore extending in a workpiece along a longitudinal bore axis includes providing a holder for holding a workpiece; directing a laser beam into the workpiece bore; and providing a mirror in the workpiece bore for directing the laser beam against a portion of the surface to be heated. The workpiece is cooled adjacent the portion of the surface to be heated by the workpiece holder. The workpiece and mirror are moved relative to each other longitudinally back and forth along the workpiece bore axis and rotatably about the workpiece bore axis, to produce a preselected pattern of heated area on the workpiece bore surface.

Abstract: A device for laser heating the surface of a small diameter bore in a workpiece includes a workpiece holder, optics for focusing a laser beam and introducing the laser beam into a bore and directing the beam against the bore surface. The workpiece holder and workpiece are movable longitudinally and rotationally with respect to the optics in the bore, to permit the laser beam to move along the bore. A first fluid cooling circuit cools the workpiece holder and workpiece, a second fluid cooling circuit cools the optics in the bore. Shielding gas is introduced into the bore to shield the bore surface being heated.

Abstract: A process for producing a crack-free, laser nitride-hardened layer on a titanium substrate, the process including preheating the substrate, melting a small area of substrate with a laser, and shrouding the melted area with a gas mixture having a maximum critical amount of nitrogen not greater than 85%. A crack-free pump shaft so hardened to Rockwell 52 C is produced.

Abstract: A process for producing a crack-free, laser nitride-hardened layer on a titanium substrate, the process including preheating the substrate, melting a small area of substrate with a laser, and shrouding the melted area with a gas mixture having a maximum critical amount of nitrogen not greater than 85%. A crack-free pump shaft so hardened to Rockwell 52 C is produced.