HASTELLOY® alloy X (HX) (UNS N06002)
Ni 47.5, Cr 21.8, Fe 18.5, Ni 9.0
Readily cold worked in a manner similar to that for austenitic (300 series) stainless steels except that this alloy is somewhat "stiffer" and may require more forming pressure. After severe cold working the product can be solution annealed as indicated in "Heat Treating".
The alloy can be aged, after solution heat treatment, at temperatures of 1200 to 1600 F.
Aging will result in a slight increase in strength and hardness with the effect being related to hours of exposure at the aging temperature- the longer the time the greater the effect.
Hardened by cold working and somewhat by aging. This alloy is not hardenable by conventional heating and quenching as with plain carbon steels.
Hardness is typically 200 BHN and never higher than 241 BHN by specification. The material is usually used in the solution treated (annealed) condition. Grain structure remains austenitic at both low and elevated temperatures.
Forging of HASTELLOY alloy X billets is carried out at temperatures of from 1750 to 2200 Deg. F. The minimum temperature is dependent on the nature and degree of working. Here are some general rules that should be followed in forging HASTELLOY alloy X:
Soak billets or ingots one hour at forging temperature for each inch of thickness.
Reheat the alloy each time temperature drops to a point where further reduction might tend to fracture the metal.
Do not raise forging temperature to compensate for loss of heat. This may cause incipient melting.
In forging ingots, use light, rapid blows until cast structure is broken up. After cast structure is broken up, heavy blows may be used.
Do not attempt to change the general shape of an ingot, as from square to round, during the initial stages of forging. Work from square to octagon. Then round off the octagon using V-shaped bottom die.
Remove any cracks or tears that develop during forging. Very often this can be done while the metal is still under the hammer.
Descaling and Pickling
HASTELLOY alloy X is relatively inert to cold acid pickling solutions. After heat-treatment, the oxide film is more adherent than that on stainless steels. Molten caustic baths followed by acid pickling have been found to be most efficient. Two such molten caustic methods employ the use of baths of "Virgo" descaling salt (Hooker Electrochemical Company).
HASTELLOY® is a registered trademark of Haynes International, Inc.