Excellent High-Temperature Strength, Low Thermal Expansion Characteristics, and Good Oxidation Resistance
HAYNES® 242™
HAYNES® 242™ is an age hardenable Ni-Mo-Cr alloy which derives its strength from a long-range ordering reaction upon aging. It has tensile and creep strength properties up to 13000°F (7050°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 15000°F (8150°C). Other attractive features include excellent low cycle fatigue properties, very good thermal stability, and resistance to high-temperature fluorine and fluoride environments.
Applications
HAYNES® 242 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, alloy 242 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 alloy 242 has also been shown to provide for excellent service in fluoroelastomer process equipment, such as extrusion screws.
Fabrication
HAYNES® 242 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.
Welding Procedures
Welding procedures common to most high-temperature, nickel-base alloys are recommended. These include use of stringer beads and an interpass temperature less than 2000°F (950°C). Preheat is not required. Cleanliness is critical, and careful attention should be given to the removal of grease, oil, crayon marks, shop dirt, etc. prior to welding. Because of the alloy's high nickel content, the weld puddle will be somewhat "sluggish" relative to steels. To avoid lack of fusion and incomplete penetration defects, the root opening and bevel should be sufficiently open.
Filler Metals
HAYNES 242 should be joined using matching filler metal. If shielded metal arc welding is used,
HASTELLOY® W coated electrodes are suggested.
Heat Treatment
HAYNES® 242 is normally used in the fully-aged condition. However, following forming and welding, a full solution anneal is recommended prior to aging in order to develop the best joint and overall mechanical properties.
Post-Weld Heat Treatment
HAYNES® 242 alloy is normally used in the fully-aged condition. However, following forming and welding, a full solution anneal is recommended prior to aging in order to develop the best joint and overall mechanical properties.
| Nominal Chemical Composition (%) |
| Ni |
Mo |
Cr |
Fe |
Co |
Mn |
Si |
Al |
C |
B |
Cu |
| Bal |
24.0-36.0 |
7.0-9.0 |
2.0 max |
2.5 max |
0.8 max |
0.8 max |
0.5 max |
0.03 max |
0.006 max |
0.50 max |
