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Material: Monel 400 and K500
Type: Round bar,Square bar,Hex bar,Flat bar
Tolerance: H7 H9 H10 H11
Surface: Black or Bright or Pickling white
Diameter: 5~500mm
Length: ≦12M or As Per Client's Requirements.
Monel round bars are solid, cylindrical metal bars manufactured from Monel alloys—a family of nickel-copper alloys.
For applications requiring resistance to chloride ion stress corrosion cracking, Monel alloys are frequently superior to austenitic stainless steels. In seawater service, Monel 400 has been documented to outperform 316 stainless steel by a factor of 10 to 1 in terms of crevice corrosion resistance. Its high mechanical strength, combined with ease of fabrication, makes it the preferred choice for pump shafts, valve stems, fasteners, and marine hardware.
JN Alloys supplies Monel round bars in standard and custom sizes, supporting projects from prototype development to large-scale industrial deployment.
Type | Round Bar Square Bar Hexagon Bar Flat Bar | ||
Surface | Black or Bright or Pickling white | ||
Standard | SUS, AISI, DIN | ||
Manufacture Technique | Hot Rolling, Cold-drawing | ||
Diameter | 5~500mm | ||
Length | ≦12M or As Per Client's Requirements. | ||
Diameter Tolerance | H7 H9 H10 H11 | ||
Material Grade | Monel 400 and K500 | ||
Key Characteristics of Monel Alloys
•Exceptional resistance to seawater and brackish water
•High strength that increases at sub-zero temperatures (cryogenic service)
•Excellent resistance to hydrofluoric acid, sulfuric acid, and alkaline media
•Non-magnetic in all conditions
•Good fabricability and weldability with matching filler metals
•Resistance to stress corrosion cracking in fluoride-containing environments
Monel 400 is the most widely used grade in the Monel family. It is a single-phase austenitic alloy with approximately 63% nickel and 33% copper, with small amounts of iron, manganese, and carbon. The alloy offers outstanding resistance to seawater, steam, and a wide range of corrosive media.
Element | Minimum | Maximum | Typical |
Nickel (Ni) | 63.0% | 70.0% | 66.0% |
Copper (Cu) | 28.0% | 34.0% | 31.5% |
Iron (Fe) | - | 2.5% | 1.5% |
Manganese (Mn) | - | 2.0% | 1.0% |
Carbon (C) | - | 0.30% | 0.15% |
Silicon (Si) | - | 0.5% | 0.3% |
Sulfur (S) | - | 0.024% | 0.01% |
Source: ASTM B164-03(2020) Standard Specification for Nickel-Copper Alloy Bar and Rod; Special Metals Corporation Monel Alloy 400 Data Sheet
Monel K-500 is a precipitation-hardenable version of Monel 400. By adding aluminum (2.3-3.15%) and titanium (0.35-0.85%), it achieves significantly higher mechanical properties through age hardening. This makes it suitable for applications requiring higher strength and hardness while retaining the excellent corrosion resistance of Monel 400.
Element | Minimum | Maximum | Typical |
Nickel (Ni) | 63.0% | 70.0% | 66.0% |
Copper (Cu) | 27.0% | 33.0% | 29.5% |
Aluminum (Al) | 2.30% | 3.15% | 2.7% |
Titanium (Ti) | 0.35% | 0.85% | 0.6% |
Iron (Fe) | - | 2.0% | 1.0% |
Manganese (Mn) | - | 1.5% | 0.8% |
Carbon (C) | - | 0.25% | 0.10% |
Silicon (Si) | - | 0.5% | 0.3% |
Sulfur (S) | - | 0.010% | 0.005% |
Source: ASTM B865-04(2020) Standard Specification for Nickel-Copper Precipitation-Hardenable Alloy Bar and Rod; Special Metals Corporation Monel Alloy K-500 Data Sheet
Bar Type | Process | Surface Finish | Typical Diameter Range | Applications |
Hot-Rolled Bar (HR) | Hot rolling at 900-1200°C | Oxide scale, rough | 12-300 mm | Structural, general machining |
Forged Bar | Open-die or closed-die forging | Rough to semifinished | 50-600 mm | Shafts, glands, flanges |
Cold Drawn Bar (CD) | Cold drawing through die | Bright, smooth | 3-80 mm | Precision parts, fasteners |
Centerless Ground Bar | Grinding after CD | Ra 0.4-0.8 µm | 3-100 mm | Valve stems, pump shafts |
Turned & Polished Bar | Machining to spec | Ra 0.8-1.6 µm | 10-200 mm | Precision shafts, aerospace |
Peeled Bar | Rotary peeling (Röhm) | Bright, clean | 20-150 mm | Oil & gas, chemical processing |
Monel alloys are typically produced using vacuum induction melting (VIM) followed by argon oxygen decarburization (AOD) or electro-slag remelting (ESR). This dual-melt process ensures low gas content (oxygen < 10 ppm, hydrogen < 3 ppm), minimal inclusions, and consistent composition across heats.
For large-diameter bars and special profiles, open-die or radial forging is used. Forging temperatures range from 900°C to 1150°C. Controlled forging ensures uniform grain structure and optimal mechanical properties. Bars are typically forged to near-net shape to minimize machining allowance.
Medium-diameter bars are hot rolled from blooms or billets on reversing or continuous rolling mills. The rolling temperature is controlled to achieve the desired surface quality and dimensional accuracy. Hot-rolled bars are typically supplied with an oxide scale surface.
Cold drawing, centerless grinding, and turning are used to achieve tight dimensional tolerances and superior surface finishes. Cold working also increases strength (work hardening). For Monel K-500, a solution treatment and age hardening cycle is applied after cold finishing to achieve peak hardness.
Every heat of Monel bar undergoes rigorous quality control:
• Chemical analysis (spark emission or ICP) per heat
• Tensile testing at room temperature (and elevated temperature on request)
• Hardness testing (Brinell or Rockwell)
• Ultrasonic testing (UT) for internal soundness in critical applications
• Hydrostatic pressure testing for nuclear and pressure vessel applications
• Intergranular corrosion testing per ASTM G28 Method A
• PMI (Positive Material Identification) verification
Standard | Title | Applies To | Key Requirements |
ASTM B164 | Nickel-Copper Alloy Bar and Rod | Monel 400, R-405 | Chemical, mechanical, dimensions |
ASTM B865 | Nickel-Copper Precipitation-Hardenable Alloy Bar and Rod | Monel K-500 | Chemical, mechanical, heat treatment |
ASTM B127 | Nickel-Copper Alloy Plate, Sheet, and Strip | Monel 400 | Plate/sheet reference for bar |
ASME SB-164 | Section II Part B ASME Boiler Code | Monel 400 bar | Acceptance criteria for pressure parts |
ASME SB-865 | Section II Part B ASME Boiler Code | Monel K-500 bar | Age-hardened property requirements |
AMS 4676 | Nickel-Copper Alloy, Bars and Rods | Monel 400 | Aerospace procurement specification |
AMS 4677 | Nickel-Copper Alloy, Bars and Rods (K-500) | Monel K-500 | Aerospace procurement specification |
NACE MR0175 / ISO 15156 | Materials for H2S-Containing Environments | Monel 400, K-500 | Sour service acceptance |
EN 10088-3 | Stainless Steels - Part 3 | Ni-Cu alloys (informative) | European reference standard |
API 6A | Wellhead and Christmas Tree Equipment | Monel 400 bar | Oil & gas wellhead components |
Source: ASTM International; ASME Boiler and Pressure Vessel Code; SAE AMS Standards; NACE International; API 6A Specification
Standard | Description | Applicable Range |
ASTM A483/A483M | Standard Specification for Stainless Steel Bars | Cold finished and hot finished bars (reference) |
DIN 1013-1 | Hot rolled steel bars; round bars | General engineering bars |
ISO 1035-1 | Hot-rolled steel sections - tolerances | International dimensional reference |
EN 10060 | Hot rolled steel round bars - tolerances | European market bars |
Source: ASTM A483/A483M; DIN 1013-1; ISO 1035-1; EN 10060
Property | Monel 400 (Annealed) | Monel 400 (Half-Hard) | Monel K-500 (Annealed) | Monel K-500 (Age-Hardened) |
Tensile Strength, min (MPa) | 480 | 620 | 480 | 1100 |
Yield Strength, min (MPa) | 195 | 415 | 195 | 790 |
Elongation, min (%) | 35 | 25 | 35 | 20 |
Hardness (Brinell) | 110-150 | 160-200 | 110-150 | 265-346 |
Hardness (Rockwell B) | 60-73 | 83-88 | 60-73 | 28-35 HRC |
Reduction of Area (%) | 60 | 50 | 60 | 45 |
Source: ASTM B164/B865; Special Metals Corporation Data Sheets; ASME SB-164/SB-865
Temperature (°C) | Monel 400 Tensile Strength (MPa) | Monel 400 Yield Strength (MPa) | Monel K-500 Age-Hardened Tensile (MPa) |
Room Temp (20°C) | 480-550 | 195-240 | 1100-1240 |
100°C | 450-520 | 185-230 | 1050-1180 |
200°C | 430-500 | 175-220 | 1000-1120 |
300°C | 410-480 | 165-210 | 960-1080 |
400°C | 390-460 | 155-200 | 920-1040 |
500°C | 370-440 | 145-190 | 870-990 |
600°C | 340-410 | 135-180 | 800-920 |
Source: Special Metals Corporation Data Sheet for Monel Alloy 400 (rev. 2004); ASME Code Case 2352
Monel alloys are among the few materials that actually increase in strength and ductility at sub-zero temperatures, with no ductile-to-brittle transition. This makes Monel 400 an excellent choice for cryogenic service, LNG transport, and liquid gas handling equipment.
Temperature | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) |
Room Temp (20°C) | 480 | 195 | 40 |
-40°C | 510 | 210 | 42 |
-80°C | 545 | 230 | 44 |
-196°C (LN2) | 620 | 275 | 48 |
-253°C (LH2) | 710 | 320 | 52 |
Source: Special Metals Corporation Monel Alloy 400 Data Sheet; LNG Industry Guidelines (IGC Code)
Industry | Application Examples | Monel Grade Preferred | Key Performance Factor |
Marine Engineering | Propeller shafts, pump shafts, seawater valves, strainers | 400 | Seawater corrosion resistance |
Oil & Gas (Sour Service) | Tubing hangers, seal rings, fastener, downhole tools | 400, K-500 | H2S resistance per NACE MR0175 |
Chemical Processing | Reactor impellers, heat exchanger tubesheets, piping | 400 | HF/H2SO4/H3PO4 resistance |
Power Generation | Turbine water box internals, condensate preheaters | 400 | Phosphate and pH control environments |
Aerospace | Aircraft structural parts, landing gear components | K-500 | High strength + corrosion resistance |
Oil & Gas (Subsea) | Subsea manifold components, umbilical hardware | 400 | Deepwater H2S + CO2 + chloride |
Pharmaceutical & Food | Mixing tanks, transfer piping for organic acids | 400 | FDA/USDA compliant, no contamination |
Desalination | brine heaters, vaporizers, brine recirculation pumps | 400 | High chloride brine resistance |
Paper & Pulp | Digester components, bleaching plant hardware | 400 | Cl2-containing environments |
Cryogenics & LNG | LNG transport tank internals, cryogenic valves | 400 | Strength increase at cryogenic temps |
Condition | Heat Treatment | Tensile Strength | Yield Strength | Elongation | Hardness |
Annealed (A) | 925-1050°C, water quench | 480-550 MPa | 195-240 MPa | 35-40% | 110-150 HB |
Half-Hard (H) | 925-1050°C, water quench + 50% CW | 620-700 MPa | 415-520 MPa | 25-30% | 160-200 HB |
Full Hard (H4) | 925-1050°C, water quench + cold work | 700-780 MPa | 550-620 MPa | 15-20% | 195-220 HB |
Source: Special Metals Corporation Monel Alloy 400 Data Sheet; ASTM B164
Condition | Heat Treatment Steps | Tensile Strength | Yield Strength | Elongation | Hardness |
Solution Annealed (A) | 980°C / 1h, water quench | 480-550 MPa | 195-240 MPa | 35-40% | 110-150 HB |
Precipitation Hardened (PH) | 980°C / 1h, WQ + 595°C / 16h, AC | 1100-1240 MPa | 790-930 MPa | 20-28% | 265-346 HB (~28-35 HRC) |
Double Aged | 980°C / 1h, WQ + 845°C / 4h, FC + 595°C / 16h, AC | 1150-1300 MPa | 850-970 MPa | 18-25% | 285-360 HB (~30-38 HRC) |
Source: ASTM B865; Special Metals Monel Alloy K-500 Data Sheet; AMS 4677
