Abstract
A powder metallurgy (P/M) coextrusion process for superalloy-clad steel pipes has been developed. Composite billets consisting of an Alloy625 powder layer and a wrought steel hollow billet were hot-extruded and defect-free Alloy625/2 1/4Cr-lMo steel-clad pipes were experimentally produced in commercial production facilities. The pipes were proved to have an uniform layer of cladding in longitudinal and circumferential directions. The bonding properties of the P/M-clad pipe were evaluated in shear tests, tensile tests and bend tests. Ultrasonic evaluation was carried out on the full length of the clad pipe but no defects, such as disbonding or cracking at the interface, were found. Based on the results obtained, P/M superalloy-clad steel pipes would be applicable to oil-field line pipes and chemical plant tubes.
