Principal Features

Excellent High-Temperature Strength, Low Thermal Expansion Characteristics, and Good Oxidation Resistance
HAYNES® 242® alloy (UNS N10242) is an age-hardenable nickel-molybdenum chromium alloy which derives its strength from a long-range ordering reaction upon aging. It has tensile and creep strength properties up to 1300°F (705°C) which are as much as double those for solid solution strengthened alloys, but with high ductility in the aged condition. The thermal expansion characteristics of 242® alloy are much lower than those for most other alloys, and it has very good oxidation resistance up to 1500°F (815°C). Other attractive features include excellent low cycle fatigue properties, very good thermal stability, and resistance to high-temperature fluorine and fluoride environments.

Fabrication
HAYNES® 242® alloy has very good forming and welding characteristics in the annealed condition. It may be forged or otherwise hot-worked by conventional techniques, and it is readily cold formable. Welding may be performed in the annealed condition by standard gas tungsten arc (GTAW) or gas metal arc (GMAW) techniques. Use of matching composition filler metal is suggested. For further information on forming and fabrication, contact Haynes International.

Heat Treatment
HAYNES® 242® alloy is furnished in the annealed condition, unless otherwise specified. The alloy is usually annealed in the range of 1900-2050°F (1038-1121°C), depending upon specific requirements, followed by an air cool (or more rapid cooling) before aging. A water quench is recommended for heavy section components. Aging is performed at 1200°F (650°C) for a period of 24-48 hours, followed by an air cool.

HAYNES® 242® alloy is produced in the form of reforge billet, bar, plate, sheet, and wire welding products, all in various sizes. Other forms may be produced upon request.

Applications
HAYNES® 242® alloy combines properties which make it ideally suited for a variety of component applications in the aerospace industry. It will be used for seal rings, containment rings, duct segments, casings, fasteners, rocket nozzles, pumps, and many others. In the chemical process industry, 242® alloy will find use in high-temperature hydrofluoric acid vapor-containing processes as a consequence of its excellent resistance to that environment. The alloy also displays excellent resistance to high-temperature fluoride salt mixtures. The high strength and fluorine environment-resistance of 242® alloy has also been shown to provide for excellent service in fluoroelastomer process equipment, such as extrusion screws.

HAYNES® 242® alloy derives its age-hardened strength from a unique long-range-ordering reaction which essentially doubles the un-aged strength while preserving excellent ductility. The ordered Ni2(Mo,Cr)-type domains are less than a few hundred Angstroms in size, and are visible only with the use of electron microscopy.

Micropage2

Transmission electron micrograph showing long-range-ordered domains (dark lenticular particles) in 242® alloy. (Courtesy Dr. Vijay Vasudevan, University of Cincinnati). Sample was solution heat treated at 2012°F (1100°C) and aged for 100 hours at 1200°F (650°C).