Development of Small Diameter Haynes® 282® Alloy Heat Exchanger Tubes by Tube Drawing

There is a need for small diameter (less than ½ inch (12.7mm) diameter) air to air heat exchanger tubes with greater creep resistance than that provided by the solid solution alloy 625 or second phase strengthened alloys 718 and X750 currently available.

Haynes^® 282^® (AMS 5951, UNS N07208) is a Nickel base super alloy that is strengthened through precipitation of a gamma prime second phase and secondary carbides. The alloy is designed to achieve superior high temperature creep strength while retaining good room temperature and hot ductility.

Tube drawing involves large tensile deformation strains. Previous alloys with higher creep resistance do not possess sufficient room temperature ductility to withstand these tensile strains. The unusual combination of high creep resistance, moderate room temperature ductility and resistance to strain age cracking offered by the Haynes^® 282^® alloy qualify this material as a candidate for small diameter tube process development.

This paper describes the methods used for process development of small diameter custom tubes of this alloy in both Seamless and Welded and Drawn product forms. It describes the thermomechanical processing, mechanical testing and in-process and final inspection of the tubular product. The small diameter tubes manufactured by the developed process are suitable for use in high temperature gas to gas heat exchangers for demanding aerospace applications.