Abstract: A manufacturing method which manufactures articles which have hollow areas inside them which are subject to their own internal vacuum. A 3-D printer can be located inside a vacuum chamber and the article(s) can be 3-D printed, thereby the hollow area inside each such article is subject to its own vacuum. When removed from the vacuum chamber, the article's hollow area remains subject to its own internal vacuum.

Abstract: A method for welding a first powder metallurgical (PM) part to a second powder metallurgical (PM) part includes: working a first face of the first PM part; working a first face of the second PM part; and friction welding the first face of the first part to the first face of the second part.

Abstract: A method is provided including heating a workpiece beyond a transformation temperature. The workpiece has at least one internal surface that has a nominal diameter, and a transformation diameter that corresponds to the start of a transformation from a first state to a second state. The method includes inserting a quench plug assembly into the workpiece. The quench plug assembly includes at least one contact surface. The at least one contact surface has a diameter that is larger than the nominal diameter and at least as large as the transformation diameter. The method includes quenching the workpiece with the quench plug assembly disposed in the bore of the workpiece. The at least one internal surface is contacted and restrained by the at least one contact surface while the workpiece transforms from the first state to the second state. Also, the method includes removing the quench plug assembly from the workpiece.