Monel 400 Round Bars | ASTM B164 UNS N04400 Bar Stock

Monel 400 is a nickel-copper alloy containing at least 63% nickel and 28 to 34% copper, with small additions of iron, manganese, carbon, and silicon. It is the most widely used grade in the Monel alloy family and is recognised for outstanding resistance to corrosion across marine, chemical processing, oil and gas, and aerospace environments. The alloy resists seawater, hydrochloric acid, hydrofluoric acid (when de-aerated), alkalis, and a wide range of organic and inorganic compounds.

Monel 400 is a solid-solution alloy. It cannot be hardened by heat treatment and is strengthened only by cold working. This makes it dimensionally stable and highly predictable in machined applications, which is a key reason engineers specify it for pump shafts, valve stems, and precision-turned components.

Monel 400 Round Bars are rated for continuous service up to 480 degrees C (900 degrees F) and retain good tensile strength, ductility, and toughness across this entire temperature range. The alloy is attacked in sulfur-bearing gases above approximately 370 degrees C (700 degrees F) and should not be used with molten sulfur above approximately 260 degrees C (500 degrees F). 

Tolerances as per ASTM B164 / ASME SB164 unless otherwise specified. Custom tolerances available on request.

Sizes from 3 mm to 800 mm are available on request. The table below shows standard ready-stock diameters with approximate weight per metre (density 8.8 g/cm3).

• Marine Engineering: Monel 400 bar stock is used for propeller shafts, pump shafts, valve stems, and seawater piping where continuous immersion in brackish or saline water is unavoidable. Its low corrosion rate in rapidly flowing seawater makes it suitable for applications that 316L stainless steel cannot handle. Typical marine components include boat shafts, bearing bars, and impeller shafts.
• Chemical Processing: The alloy is widely used in heat exchangers, reaction vessels, and piping systems handling acids, alkalis, and chloride-bearing process streams. Its resistance to hydrochloric and hydrofluoric acid (when de-aerated) is particularly valued in pharmaceutical and specialty chemical production.
• Oil and Gas: Monel 400 round bar is specified for pump shafts, valve stems, wellhead components, and downhole tools where resistance to sour service environments and produced water is required. NACE MR0175 / ISO 15156 compliance is available on request for sour service applications.
• Aerospace and Defence: AMS 4675 specification covers Monel 400 bar for aerospace applications. The alloy is used in fuel and oxidiser systems, fasteners, and structural components where corrosion resistance and consistent mechanical properties are critical. The QQ-N-281 federal specification applies to defence procurement.
• Nuclear and Uranium Processing: Monel 400 is one of the few alloys resistant to uranium hexafluoride (UF6) and hydrofluoric acid, making it the standard material for uranium enrichment plant components, gaseous diffusion barriers, and other nuclear processing equipment.
• Pulp and Paper: The alloy resists the bleaching agents, chlorine compounds, and acidic process liquors encountered in pulp and paper production. It is used in digesters, bleach plant piping, and drum-type washers.
• Desalination and Water Treatment: Monel 400 round bars are used in desalination plant components, brine heaters, and evaporator tubing sheets where constant exposure to high-salinity water would rapidly corrode lower-grade alloys. 

• Jade Alloys has supplied certified nickel alloy products for over two decades, serving OEM procurement teams, EPC contractors, and MRO distributors across the oil and gas, chemical, and marine sectors. Every order of Monel 400 round bar is accompanied by an EN 10204 3.1 Mill Test Certificate traceable to the melt heat number.
• Over 20 years of experience as an exporter, with active customers in 50+ countries across the Middle East, Europe, Southeast Asia, and the Americas.
• Certified raw materials sourced from NACE-approved mills, with full chemical and mechanical traceability from melt to finished bar.
• All Monel 400 Round Bars supplied with EN 10204 3.1 Mill Test Certificates. NACE MR0175 / ISO 15156 compliance available on request for sour service applications.
• No minimum footage requirements. We supply the exact quantity required, from 1 kg trial orders to multi-tonne project packages.
• Same-week dispatch from Mumbai warehouse for standard stock sizes. Express export documentation including Bill of Lading, Country of Origin Certificate, and Copy of Invoice.
• Value-added services: heat treatment and annealing, machining and centreless grinding, pickling, polishing, rolling, and forging.

• Pre-Weld Preparation:
  Ensure surfaces are clean and free of oil, grease, scale, and all contaminants before welding.
• Recommended Welding Methods:
  Use GTAW (TIG) or GMAW (MIG) with appropriate filler metals such as ERNiCu-7. SMAW with ENiCu-7 electrodes is also acceptable for site work.
• Heat Input Control:
  Control heat to minimise distortion and cracking. Maintain low interpass temperatures. Excessive heat input increases the risk of hot cracking and grain boundary weakening.
• Post-Weld Treatment:
  Clean welds thoroughly to remove any oxide contamination. Consider stress relief annealing for thick sections or highly restrained joints.
• Cracking Risks:
  Monitor for hot cracking in the heat-affected zone and hydrogen embrittlement when welding in humid or contaminated conditions.
• Testing and Inspection:
  Use non-destructive testing methods such as dye penetrant or radiographic inspection to verify weld integrity, especially for pressure-bearing applications.

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