ThePipingMart Blog Grades Hastelloy X Alloy (UNS N06002) – Composition, Properties and Uses

Hastelloy X Alloy (UNS N06002) – Composition, Properties and Uses

Hastelloy X

This post will go through the composition, mechanical and physical properties, uses, corrosion resistance, heat treatment, machining, and welding of Hastelloy X.

What is Hastelloy X?

Hastelloy X, also known as HX, is a nickel-based alloy known for its exceptional strength and heat resistance. Being a superalloy, Hastelloy X is widely used in applications that require reliable performance in extreme environments such as high temperatures and corrosive conditions.

Hastelloy X Composition

Hastelloy X comprises varying amounts of nickel, molybdenum, chromium, and iron. Additionally, this alloy contains small amounts of tungsten, cobalt, and carbon. The chemical composition provides the alloy with excellent corrosion resistance and mechanical strength.

Element Content (%)
Cr, Chromium 20.5-23
Fe, Iron 17-20
Mo, Molybdenum 8-10
Mn, Manganese 1 max
Si, Silicon 1 max
Ti, Titanium 0.15 max
Co, Cobalt 0.5-2.5
Al, Aluminum 0.5 max
Cu, Copper 0.5 max
C, Carbon 0.05-0.15
P, Phosphorus 0.04 max
S, Sulfur 0.03 max
W, Tungsten 0.2-1
B, Boron 0.008 max
Ni, Nickel Remainder

Hastelloy X Mechanical Properties

Hastelloy X has high strength due to its optimal combination of nickel, molybdenum, and chromium content. It is known for its ability to withstand high temperatures above 1000 °F while retaining strength. It exhibits exceptional mechanical properties such as excellent tensile and yield strength, good ductility, and toughness.

Properties Metric Imperial
Tensile strength 755 MPa 109.5 Ksi
Yield strength 385 MPa 55.9 Ksi
Elastic modulus 205 GPa 29.8 psi
Reduction of area 22% 22%
Hardness, Rockwell B (converted from Brinell hardness) 87 87

Hastelloy X Physical Properties

Hastelloy X has a high thermal conductivity level and a low thermal expansion coefficient. It has a specific gravity of 8.22 g/cm³ and a melting point of 2,381°C (4,318 °F). It also has an excellent resistance to thermal fatigue.

Properties Metric Imperial
Density 8.220 g/cm³ 0.297 lb/in³
Melting point 1316°C 2400°F

Hastelloy X Equivalent

AISI 680 AMS 5587 AMS 5754 ASTM B435 ASTM B572
AMS 5588 AMS 5536 AMS 5798 ASTM B619 ASTM B366
ASTM B622 ASTM B626 PWA 1038 DIN 2.4665 DIN 2.4603
GE B50A436 GE B50A463 GE B50T83A GE B50TF24 GE B50TF25
GE B50TF31

Hastelloy X Thermal Properties

Properties Metric Imperial
Thermal expansion co-efficient 13.0 µm/m°C 7.2 µin/in°F
Thermal conductivity 9.1 W/mK 63 BTU in/hr.ft².°F

Hastelloy X Uses

Hastelloy X is used in various industrial applications, including gas turbines, jet engines, furnace hardware, and petrochemical processing equipment. It is also used in aerospace due to its exceptional high-temperature strength and corrosion resistance.

Hastelloy X Corrosion Resistance

Hastelloy X has excellent corrosion resistance against various corrosive media, including sulfuric acid, hydrochloric acid, and nitric acid. It is also resistant to oxidizing media such as seawater and most organic acids. These properties make it an ideal choice for harsh environments with a high risk of corrosion.

Hastelloy X Heat Treatment

Hastelloy X can be heat-treated to enhance its strength and toughness. The alloy can be readily annealed by heating it up to 2150°F followed by air-cooling. Tempering can also be done by heating it to 1900°F followed by air-cooling to enhance its toughness.

Hastelloy X Machining

Hastelloy X has excellent machinability when compared to other nickel-based superalloys. However, due to its high strength, the machining process should be done with appropriate tools and techniques to avoid tool wear and breakage. Coolant is also recommended to prevent overheating, which can lead to work hardening or cracking.

Hastelloy X Welding

Hastelloy X is weldable by various welding methods, including Gas Tungsten Arc Welding (GTAW), Gas Metal Arc Welding (GMAW), and Submerged Arc Welding (SAW). GTAW is preferred due to its high-quality welds and lower heat input, which reduces the possibility of cracking.


In conclusion, Hastelloy X is an outstanding nickel-based superalloy known for its strength, heat, and corrosion resistance. Its excellent properties make it ideal for various industrial applications, including aerospace, gas turbines, furnace hardware, and petrochemical processing equipment. The ability to heat-treat, machine, and weld Hastelloy X gives it a broader range of applications in different industries. However, choosing Hastelloy X requires understanding its properties and carefully considering its application requirements.

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