ASTM B165 N04400 Parameters and Specifications

ASTM B165 N04400 refers to the N04400 alloy products in the ASTM B165 standard.

ASTM B165 N04400

ASTM B165, a standard specification developed by the American Society for Testing and Materials (ASTM), stands for "Standard Specification for Nickel-Copper Alloy Seamless Tubing." This standard specifically applies to cold-finished seamless tubing made from UNS N04400 alloy and specifies detailed requirements for chemical composition, mechanical properties, dimensional tolerances, test methods, and acceptance criteria.

For example, the standard specifies a minimum tensile strength of 480 MPa, a minimum yield strength of 170 MPa, and a minimum elongation of 35% for annealed tubing. This standard is designed to ensure reliable quality and consistent performance in critical applications such as seawater treatment, the chemical and petroleum industries, and power plants. It has been approved for use by agencies such as the US Department of Defense.

ASTM B165

UNS N04400, commonly known as Monel 400 or Nickel-Copper Alloy 400, is a single-phase solid solution alloy with nickel as the base and copper as the primary alloying element.

It possesses many excellent properties: excellent corrosion resistance, effectively resisting seawater, hydrofluoric acid, sulfuric acid, phosphoric acid, and hot concentrated alkali solutions, and strong resistance to chloride stress corrosion cracking; excellent mechanical properties, maintaining stable strength and good toughness from cryogenic temperatures to approximately 600°C, and being able to be strengthened by cold working; and excellent machinability and weldability.

As a result, it is widely used in the manufacture of key components such as pump shafts and propellers in offshore engineering, vessels and piping in the chemical processing industry, nuclear fuel production equipment, and heat exchangers.

UNS N04400 Introduction

The following is a detailed table of the chemical composition of ASTM B165 UNS N04400 alloy:

Composition	Chemical Symbols	Value (wt%)	Functions
Nickel	Ni	≥ 63.0	As a matrix element, it provides good toughness and resistance to corrosion in reducing media. It synergizes with copper to form a high-strength single-phase solid solution.
Copper	Cu	28.0 - 34.0	A major alloying element, it significantly improves the alloy's corrosion resistance in reducing acids and seawater.
Iron	Fe	≤ 2.5	A common residual element, its content must be strictly controlled to avoid adversely affecting the alloy's corrosion resistance.
Carbon	C	≤ 0.30	A low-temperature element. Excessive content can affect weldability and intergranular corrosion resistance, so an upper limit is imposed.
Manganese	Mn	≤ 2.0	It acts as a deoxidizer and helps improve the material's hot working properties.
Silicon	Si	≤ 0.50	As a deoxidizer, it is a common residual element in the smelting process and its content must be kept to a low level.
Sulfur	S	≤ 0.024	A harmful impurity. A low-melting eutectic, its content must be extremely low to prevent hot cracking during hot working or welding.

The following is a summary of the main physical properties of UNS N04400 (Monel 400) alloy as specified by ASTM B165.

Physical Properties	Value/Description	Condition
Density	8.83 - 8.90 g/cm³	Measured at room temperature.
Melting Point Range	1300 - 1350 °C	2370 - 2460 °F.
Thermal Conductivity	24.0 W/m·°C	Measured at 100°C (212°F).
Specific Heat	445 J/kg·°C	Measured at 100°C (212°F).
Linear Expansion Coefficient	14.2 μm/m·°C	Measured at 100°C (212°F).
Magnetic Properties	Non-magnetic	Measured at 100°C (212°F).

The following is a summary of typical mechanical properties of UNS N04400 alloy as per ASTM B165. These properties may vary depending on the specific form and supply status of the product.

Performance Parameters	Value
Tensile Strength (σb)	≥ 480 MPa 482 - 827 MPa
Yield Strength (σs)	≥ 195 MPa 170 - 690 MPa
Elongation (δ)	≥ 35% 15% - 60%
Hardness (HB)	135 - 179 Max 241 HB
Reduction of Area (ψ)	30%
Density	8.9 g/cm³

ASTM B165 N0440 Properties

Corrosion Resistance

UNS N04400 exhibits excellent resistance to a wide range of corrosive media, particularly in environments such as hydrofluoric acid, fluorine gas, hot concentrated alkali solutions, seawater, and sulfuric and hydrochloric acids. Furthermore, it generally does not undergo stress corrosion cracking and is highly resistant to chloride-induced stress corrosion cracking, making it an ideal material for seawater treatment equipment.

Welding and Machinability

UNS N04400 exhibits excellent machinability and can be formed into a variety of shapes through hot or cold working. However, its welding performance is relatively challenging, and defects such as hot cracking, porosity, and lack of fusion may occur.

High and Low Temperature Performance

UNS N04400 maintains reliable performance in both high and low temperature environments. At high temperatures, it can withstand continuous operation in air up to approximately 600°C and exhibits a low corrosion rate in high-temperature steam.

In terms of cryogenics, the alloy maintains good toughness even at extremely low temperatures of -196°C, which makes it suitable for cryogenic fields such as liquefied natural gas equipment.

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