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Hastelloy B2

Material: Hastelloy B2, N10665, 2.4617

Hastelloy B2, a classic nickel-molybdenum alloy developed by Haynes International in the United States, is renowned for its exceptional corrosion resistance and is a core material in the chemical and metallurgical industries. Hastelloy B2 alloy is primarily designed to protect against intergranular and knife-edge corrosion. The main differences between this alloy and Hastelloy B alloy are its reduced carbon and silicon content, with the iron content reduced from less than 6% to 2%.

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Hastelloy B2 Introduction:

Hastelloy B2 (UNS N10665/W.Nr. 2.4617) is a solid solution strengthened nickel molybdenum alloy that exhibits significant resistance to reducing environments such as hydrogen chloride gas, sulfuric acid, acetic acid and phosphoric acid. Molybdenum is a major alloying element that provides significant corrosion resistance in reducing environments. This nickel alloy can be used in the as-welded condition because it resists the formation of grain boundary carbide deposits in the weld heat-affected zone.

In addition, Hastelloy B2 has excellent resistance to pitting corrosion, stress corrosion cracking, and knife line and heat-affected zone attacks. Alloy B2 supports resistance to pure sulfuric acid and many non-oxidizing acids.

Hastelloy B2 is suitable for most chemical process applications in the as-welded state. Ideal for equipment that handles hydrochloric acid of various concentrations and temperatures. Resistant to hydrogen chloride gas and sulfuric acid, acetic acid and phosphoric acid.

The main high temperature applications are those requiring a low coefficient of thermal expansion. Exposure to temperatures between 540 and 815°C (1000-1500°F) should be avoided as the ductility of the alloy decreases. In oxidizing gases such as air, Hastelloy B2 can be used at temperatures up to 540°C (1000°F). In reducing gas or vacuum, the alloy can be used at 815°C (1500°F) to higher temperatures. When hydrochloric acid comes into contact with iron or copper, iron or copper salts may be formed, therefore Hastelloy B2 should not be used with copper or iron piping in systems containing hydrochloric acid.

Hastelloy B2 Chemical Composition

Grade	Mo	Fe≤	C≤	Co≤	Cr≤	Mn≤	Si≤	P≤	S≤	Ni
Hastelloy B2	26.0-30.0	2.00	0.02	1.00	1.00	1.00	0.10	0.04	0.03	Remainder

Hastelloy B2 Mechanical Properties

Tensile, min, ksi[MPa]	Yield, min, ksi[MPa]	Elongation, %(min)
110[760]	51[350]	40

Hastelloy B2 Standard And Products

Products	Standards	Show
Hastelloy B2 Bars	ASTM B335
Hastelloy B2 Sheets/Plates	ASTM B333, A480
Hastelloy B2 Welded Pipe	ASTM B619, B775
Hastelloy B2 Seamless Pipe	ASTM B622
Hastelloy B2 Welded Tube	ASTM B626
Hastelloy B2 Fittings	ASTM B366
Hastelloy B2 Forgings	ASTM B564

Hastelloy B2 Physical Properties

Grade	Density Room Temp.	Melting Range	Specific Heat 68°F	Elastic Modulus 68°F	Thermal Conductivity 68°F
Hastelloy B2	0.333lb/in3	2430°F to 2520°F	0.090Btu/lb. °F	31.4*106psi	64Btu/ft.h.°F

Hastelloy B2 Equivalent Grades

STANDARD	WERKSTOFF NR.	UNS	EN
Hastelloy B2	2.4617	N10665	NiMo28

Alloy B2 Properties

Corrosion Resistance:

Regarding general corrosion, Hastelloy B2 alloy's resistance to inorganic acids such as hydrochloric acid, sulfuric acid, and phosphoric acid is essentially the same as that of Hastelloy B alloy. However, its corrosion resistance is generally superior to that of Hastelloy B alloy, particularly after welding. In 20% boiling hydrochloric acid, even cold working deformation of Hastelloy B2 up to 50% does not affect its corrosion resistance.

Regarding intergranular corrosion, due to the lower carbon, silicon, and iron contents of Hastelloy B2 alloy, the carbides and intermetallic phases in the sensitized steel are far less than those in Hastelloy B alloy. Therefore, this alloy exhibits superior resistance to intergranular corrosion.

Regarding stress corrosion, tests have shown that when Hastelloy B2 alloy contains low residual Fe ≤ 2% and Cr ≤ 1.0%, the stress corrosion resistance of the latter alloy is superior to that of the same alloy with appropriately controlled Fe and Cr contents after medium-temperature aging.

Mechanical Properties:

The ductility of Hastelloy B2 alloy decreases and worsens with aging. This is due to the precipitation of the hard and brittle β phase during the intermediate-temperature aging process.

Weldability:

Hastelloy B2 alloy offers excellent weldability. Due to its low carbon, silicon, and iron content, it exhibits superior resistance to post-weld intergranular corrosion and knife-edge corrosion compared to Hastelloy B. When the iron and chromium content is properly controlled, Hastelloy B2's ductility, toughness, corrosion resistance, and weldability are further enhanced. Therefore, Hastelloy B2 generally does not require post-weld heat treatment. This alloy is more suitable for manufacturing welding equipment and components than Hastelloy B.

Heat Treatment:

Except for applications specified otherwise, this alloy requires solution treatment at 1066°C before use. Unless the Fe+Cr content in the alloy is carefully controlled, prolonged use at temperatures between 538°C and 816°C is generally not permitted.