A Comprehensive Guide to Nickel-based Super Alloy: Hastelloy X (UNS NO6002/W.Nr 2.4665)
Few materials like nickel-based superalloys in advanced material engineering can combine strength, corrosion resistance, and versatility. This comprehensive guide deeply explores the complexity and distinctive features that make Hastelloy X a true miracle of modern metallurgy.
What is Hastelloy X?
Table of Contents
- What is Hastelloy X?
- Chemical Composition Requirements of Hastelloy X
- Typical Physical Properties of Hastelloy X
- Product Forms and Standards of Hastelloy X
- The physical and chemical properties of Hastelloy X (N06002)
- Alloy structure of Hastelloy X (N06002)
- Alloy process performance and requirements of Hastelloy X (N06002)
- Heat treatment system of hastelloy X (N06002)
- Smelting and casting process of hastelloy X (N06002)
Hastelloy X, also known as “Alloy X”, is designated as UNS N06002 or W.Nr 2.4665. It is a nickel-chromium-iron-molybdenum alloy that possesses an exceptional combination of oxidation resistance, fabricability, and high-temperature strength. Hastelloy X has also been found to be exceptionally resistant to stress-corrosion cracking in petrochemical applications and resistant to carburization and nitriding. Hastelloy X (UNS N06002) is mainly made of chromium and a nickel-based superalloy with high iron content strengthened by molybdenum solid solution. It has good anti-cultivation and corrosion resistance, moderate durability and creep strength below 900℃, cold and hot working formability and welding The performance is good. Used in the manufacture of combustion chamber parts and other high-temperature parts of aero-engines, long-term use below 900 ℃, short-term working temperature up to 1080 ℃. The main products supplied are plates, strips, tubes, bars, forgings, ring parts and precision castings.
Unveiling the Origins
Hastelloy X, a member of the renowned
Hastelloy family, was conceived with an unwavering commitment to surmount the
limitations of conventional alloys. Haynes International Inc. developed this
alloy to thrive in the most unforgiving environments, such as high-temperature
combustion chambers, gas turbine engines, and industrial furnace applications.
Chemical Composition Requirements of Hastelloy X
|The Chemical Composition of Hastelloy X, %|
Typical Physical Properties of Hastelloy X
Product Forms and Standards of Hastelloy X
|Plate, sheet and strip||ASTM B435, B906|
|Seamless pipe and tube||ASTM B622|
|Welded pipe||ASTM B619, B775|
|Welded tube||ASTM B626, B751|
|Welded pipe fitting||ASTM B366|
|Billet and bar for reforging||ASTM B472|
*The mechanical properties of Hastelloy X materials vary according to different forms and heat treatment conditions.
The physical and chemical properties of Hastelloy X (N06002)
The melting temperature range of Hastelloy X (N06002): 1295-1381℃.
- Hastelloy X (N06002) alloy thermal conductivity: see Table 2-1.
- Hastelloy X (N06002) alloy specific heat capacity: Table 2-2.
- Hastelloy X (N06002) alloy linear expansion coefficient: see Table 2-3.
- Thermal diffusivity of Hastelloy X (N06002) alloy castings: see Table 2-4.
- Density of Hastelloy X (N06002): ρ=8.28g/cm3 .
- Hastelloy X (N06002) electrical properties: the resistivity is shown in Table 2-5.
- Hastelloy X (N06002) magnetic properties: the alloy is non-magnetic.
- Hastelloy X (N06002) chemical properties: see Table 3-1.
- Hastelloy X (N06002) oxidation resistance: the oxidation rate of the alloy after 100h test in air medium is shown in Table 2-6.
- Hastelloy X (N06002) mechanical properties: The mechanical properties of different varieties specified in HastelloyX technical standards are shown in Table 3-1.
Table 2 – 2
Table 2- 3
|α/10 -6 ℃ -1||12.1||12.5||13.4||14.0||14.3||14.8||15.8||16.1|
|Q/(10 -6 m 2 /S))||2.78||3.06||3.68||3.64||4.36||4.32||4.38||4.91||5.23|
|Oxidation rate/(g/(m 2 ·h))||0.0023||0.060||0.117||0.200||0.611|
|Variety||Tensile performance at room temperature σP0.2/MPa||815℃ lasting performance σb/MPa||Other properties|
|not less than||δ5/%||σ/MPa||t/h||δ5/%||Rockwell hardness|
|Cold-rolled sheet, cold-rolled strip, cold-drawn pipe, bar, ring, precision casting②||310||725||35||110||24-||8.0||Bending 180°|
① Room temperature tensile strength of strip with δ<0.25mm σb ≥725MPa, δ5 ≥25%.
② The σb ≥240MPa and δ5 ≥12 % of the precision casting at 815℃ . After 800℃, 50h, air cooling, (Rockwell hardness) HRC≤24.
Alloy structure of Hastelloy X (N06002)
- (1) The structure of the alloy in the solid solution state is an austenite matrix with a small amount of TiN and M6C carbides. After long-term aging at 700-900°C, the main precipitated phases are M12C and M3B2 , along with trace μ phase and L phase. A small amount of σ phase appeared after aging at 700°C for 200 hours, but there was no σ phase after aging at 800°C, and a trace amount of M23C6 was precipitated , sometimes a trace amount of L phase appeared. Therefore, the alloy shows a certain degree of age hardening after long-term aging, which reduces the plasticity and the high-temperature strength.
- (2) The technical standard of cold-rolled sheet stipulates that the grain size of cold-rolled sheet in the supply state should be in the range of 4-8.
Alloy process performance and requirements of Hastelloy X (N06002)
1. HastelloyX alloy forming properties:
The alloy has good cold and hot forming properties. The forging heating temperature is 1170℃±10℃, and the final forging temperature is not lower than 950℃; the slab hot rolling heating temperature is 1150℃±10℃, and the final rolling temperature is not lower than 850℃; the ring hot rolling heating temperature is 1170℃±10℃ . The high temperature tensile ductility of the alloy is shown in Figure 5-1.Figure 5-2 shows the recrystallization curve of high temperature upsetting sample after solution treatment at 1180℃ for 45min.
2. HastelloyX welding performance:
This alloy has good welding process performance and can be welded by argon arc welding, seam welding and spot welding. HHastelloyX or HGH3113 welding wire is recommended for argon arc welding.
(1) For HastelloyX manual argon arc welding butt specifications, see Table 5-1.
|Fig.5-1 High temperature tensile plasticity diagram of alloy||Fig.5-2 Recrystallization curve of upsetting sample|
|Metal material to be welded||HastelloyX＋HastelloyX|
|Thickness/mm||1.0 + 1.0|
|State before welding||Supply state or solid solution state|
|Tungsten electrode diameter/mm||1.6-2.0|
|Power supply and polarity||DC||Positive polarity|
(2) For HastelloyX automatic tungsten pulse argon arc welding butt specification, see Table 5-2.
|State before welding||Solid solution|
|Pulse amplitude ratio||3||3||3.5|
|Pulse width ratio||2||2||2|
|Wire feeding speed/(m/min)||–||0.20||0.25|
(3) For HastelloyX seam welding specifications, see Table 5-3.
|Metal material to be welded||Thickness/mm||State before welding||Roller width/mm||Welding time/s||Rest time/s||Welding speed/(m/min)||Electrode pressure/kN|
|HastelloyX＋HastelloyX||1.0 + 1.0||Solid solution or supply state||5.5||7||0.14-0.18||0.14-0.22||0.34-0.40||0.25|
|1.5 + 1.5||5.5||7||0.16-0.20||0.14-0.22||0.22-0.34||0.25|
(4) For HastelloyX spot welding specifications, see Table 5-4.
|Metal material to be welded||Thickness/mm||State before welding||Electrode diameter/mm||Welding time/s||Electrode pressure/kN||Single point shear strength/MPa||Tensile strength/MPa|
|HastelloyX＋HastelloyX||1.0 + 1.0||Solid solution or supply state||6||7||0.16-0.24||0.1-0.2||≥9.35||≥6.36|
|1.5 + 1.5||6||7||0.20-0.36||0.2-0.3||≥12.30||≥10.60|
(5) The mechanical properties of HastelloyX welded joints are shown in Table 5-5.
|State before welding||Post-weld treatment||
|Argon arc welding||1.5||Supply status||Untreated||HHastelloy X||20||800||100||–||–|
|Pulse argon arc welding||1||Supply status||Untreated||–||20||842||100||–||–|
|Seam welding||1.5||Supply status||Untreated||–||20||763||96||–||–|
- Solid solution treatment of plate parts: 1150℃±10℃, 2-15min, rapid air cooling.
- Welding parts or flame tube treatment: 980℃±10℃, 60min, air cooling.
- Stress relief treatment after machining: 870℃±10℃, 30-60min, air cooling.
- Stable dimension treatment of parts: 760℃±10℃, 2h, air cooling.
Heat treatment system of hastelloy X (N06002)
Plates and tubes: 1130-1170℃, fast air cooling or water cooling; bar and ring test samples: 1175℃±15℃, air cooling or faster cooling; strip : 1065-1105℃, rapid cooling.
Specifications and supply status of hastelloy X (N06002): supply δ0.5-4.0mm plate, δ0.05-0.8mm strip, outer diameter 4-20mm, wall thickness 1.0-2.0mm pipe , Welding wire with a diameter of 0.2-10.0mm, rods with a diameter of ≤300mm, ring parts with various diameters and wall thicknesses, and precision castings with different shapes and sizes. Plates, strips and pipes are supplied after solution treatment and pickling. Strips can also be supplied in cold rolled state; welding wire is delivered in hard state, semi-hard state, solid solution plus pickling, bright solution treatment state , Can also be delivered straight; bars and ring parts are delivered without heat treatment. Precision castings are supplied in the as-cast state.
Smelting and casting process of hastelloy X (N06002)
Adopts electric arc furnace plus electroslag or non-vacuum induction furnace plus electroslag remelting process. The production of castings uses induction furnace to remelt the master alloy and then pouring it into a heated mold shell. The pouring speed is better.
Application profile and special requirements of hastelloy X (N06002): This alloy has been widely used in foreign aero-engines and civil industries. China is mainly used to manufacture combustion chamber parts and other hot end parts and honeycomb structures. . The alloy has a certain age hardening phenomenon after long-term use at high temperature.
- Gas turbines
- Petrochemical industry
- Industrial furnaces
- Heat treating equipment
- Nuclear engineering
- Jet engine combustion chambers
- Aircraft cabin heaters
- Turbine exhaust components
Hastelloy X round bars manufactured to ASTM B572 Gr. N06002. Density: 0.297 lb/in3 [8.23 g/cm3]; Condition: hot rolled & solution annealed.
Alloy X is one of the most widely used nickel base superalloys for gas turbine engine combustion zone components such as transition ducts, combustor cans, spray bars and flame holders as well as in afterburners, tailpipes and cabin heaters. It is recommended for use in industrial furnace applications because it has unusual resistance to oxidizing, reducing and neutral atmospheres. Hastelloy X is also used in the chemical process industry for retorts, muffles, catalysts support grids, furnace baffles, tubing for pyrolysis operations and flash drier components.