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Monel 400, with the material designation 2.4360, is a nickel-copper alloy known for its excellent corrosion resistance and high strength. The heat treatment of Monel 400 UNS N04400 is limited due to its nature as a solid-solution alloy. Monel nickel alloy 400 is typically used in the annealed condition, which is achieved through a specific heat treatment process.
Overview Typical 2.4360 Monel 400 Heat Treatment Process:
1. Annealing:
The primary heat treatment for ASTM B127 UNS N04400 plate involves annealing. This process is conducted at a temperature range of 1600°F to 1900°F (870°C to 1040°C) for a duration of 1 to 4 hours, followed by air cooling or water quenching. The specific temperature and duration may vary slightly based on the desired properties and the thickness of the material.
2. Solution Annealing:
2.4360 Monel 400 is a solid-solution alloy, and solution annealing is a crucial step to homogenize the alloy's composition. During this process, the ASME SB 163 N04400 material is heated to a temperature within the range of 1725°F to 1850°F (940°C to 1010°C) and then rapidly quenched in water or another suitable medium.
3. Stress Relieving:
Stress relieving may be performed after cold working or machining processes to reduce residual stresses in the alloy 400 seamless pipe material. The nickel copper alloy 400 typical temperature for stress relieving is around 1100°F to 1400°F (595°C to 760°C), and the duration can vary based on the extent of the stress in the material.
Mechanical Properties Post-Thermal Treatment
The following data outlines the typical mechanical properties expected from Monel 400 bar and plate products depending on their heat-treated condition, helping you verify incoming Mill Test Reports (MTRs):
| Product Form & Condition | Tensile Strength (ksi / MPa) | 0.2% Yield Strength (ksi / MPa) | Elongation in 2 in. (%) | Hardness (Rockwell B) |
| Annealed (Hot-Rolled/Forged) | 70–85 / 480–585 | 25–45 / 170–310 | 35–50 | 60–75 |
| Stress-Relieved (Cold-Drawn) | 85–110 / 585–760 | 55–85 / 380–585 | 15–25 | 85–95 |
| As Cold-Worked (Heavy) | 100–130 / 690–895 | 80–115 / 550–790 | 2–10 | 95–100+ |
It's important to note that Monel 400 is not precipitation hardenable, so it does not undergo age hardening or precipitation strengthening like some other alloys. As such, The strength and hardness of ASTM B165 UNS N04400 Monel 400 is usually achieved by cold working (cold drawing or cold rolling).The heat treatment is mainly focused on annealing and solution annealing to optimize its mechanical properties and corrosion resistance.
Heat Considerations in Welding and Fabrication
During manufacturing, welding operations subject Monel 400 to localized thermal cycles that act as an uncontrolled, non-uniform heat treatment. This generates a distinct Heat-Affected Zone (HAZ) adjacent to the weld bead.
Microstructural Changes: The high heat input from welding can cause grain growth in the HAZ, leading to a localized drop in tensile strength compared to the parent cold-worked metal.
Post-Weld Heat Treatment (PWHT): Unlike carbon steels, Monel 400 does not require post-weld stress relieving or solution annealing by code for most standard operations. However, if the fabricated component is destined for high-stress environments containing hydrofluoric acid, fluorosilicic acid, or hot caustic alkalis, a full thermal stress relief (1100°F–1200°F / 595°C–650°C) is mandatory to eliminate localized weld stresses and prevent rapid Stress Corrosion Cracking (SCC).
Need Certified Monel 400 Components?
As a leading global supplier and manufacturer of high-performance nickel alloys, we supply fully certified Monel 400 (UNS N04400 / 2.4360) seamless pipes, heat exchanger tubes, plates, and custom pre-fabricated pipe spools. All products undergo strict quality control and thermal verification to meet your exact project specifications.
Contact our metallurgical engineering team today at market@htpipe.com for technical consultations, free samples, or an immediate quotation!
