RAYCHIN LIMITED

Monel Socket Head Cap Screws – Design & Configurations

Critical Applications of Monel Socket Head Cap Screws

International Standards & Global Designations – Monel Socket Head Cap Screws

RAYCHIN LIMITED manufactures Monel socket head cap screws from vacuum induction melted (VIM) material conforming to the most widely used national and international specifications. All material is traceable to the mill.

Chemical Composition (Weight %) – Monel Alloys for Socket Head Cap Screws

Our Monel socket head cap screws are produced from vacuum induction melted (VIM) material conforming to the following limits per ASTM, AMS, and industry standards.

Monel 400 (UNS N04400) Composition

Monel K-500 (UNS N05500) Composition

Metallurgical note: Monel 400 is a solid-solution nickel-copper alloy that is hardened only through cold working. It remains ductile even at subzero temperatures and does not require heat treatment for high strength properties. Monel K-500 adds aluminum and titanium to enable precipitation hardening (aging), achieving yield strengths above 690 MPa (100 ksi) while maintaining excellent corrosion resistance. Both alloys are essentially non-magnetic (K-500 is non-magnetic; Monel 400 is slightly magnetic at room temperature but loses magnetism at elevated temperatures). The high nickel content provides exceptional resistance to stress corrosion cracking, while copper enhances resistance to reducing environments such as hydrofluoric and sulfuric acids. Monel alloys were among the first nickel-based alloys developed commercially and maintain a single solid-solution phase that resists attack from a range of corrosive media that would damage both carbon steel and stainless steel.

Complete Mechanical & Physical Properties – Monel Socket Head Cap Screws (MPa / ksi)

Monel socket head cap screws are supplied in various conditions per ASTM and AMS specifications. Data represent typical values based on industry standards. ksi values (kilopound per square inch) are provided alongside MPa.

Mechanical Properties – Monel 400 Socket Head Cap Screws

Mechanical Properties – Monel K-500 Socket Head Cap Screws (Age Hardened)

Physical Properties – Monel 400 & K-500

High‑Temperature Performance of Monel Socket Head Cap Screws

Monel alloys retain useful mechanical properties at elevated temperatures up to 540°C (1000°F) and can operate in moderately elevated environments. The alloys maintain excellent ductility and toughness from cryogenic temperatures up to 500°F (260°C) continuously, with good oxidation resistance up to 1000°F. Monel K-500 is typically limited to 480°C (900°F) to prevent over-aging of the precipitation-hardened structure. In high-temperature steam, corrosion rates are less than 0.026 mm/year.

Elevated Temperature Capabilities – Monel 400

High-Temperature Comparison – Monel vs. Stainless Steel

Note: Monel excels in applications requiring maximum corrosion resistance at moderate to high temperatures, particularly in reducing environments where stainless steels may fail. Above 480°C, Monel K-500 may experience over-aging and loss of strength.

Exceptional Corrosion Resistance of Monel Socket Head Cap Screws

Monel alloys offer outstanding corrosion resistance across a wide range of aggressive environments, making them suitable for the most demanding applications including marine, chemical processing, oil & gas, and power generation.

• Seawater Corrosion: Excellent resistance to flowing and stagnant seawater, with corrosion rates below 0.025 mm/year. Virtually immune to pitting and crevice corrosion in marine environments. Renowned for saltwater corrosion resistance, Monel is the go-to material by the navy and will last many years in saltwater conditions.
• Hydrofluoric Acid (HF): Monel 400 is the standard material for HF alkylation unit piping and equipment. No other commercially available alloy offers the same combination of HF resistance and mechanical strength at reasonable cost. Offers exceptional resistance to hydrofluoric acid in all concentrations up to the boiling point – perhaps the most resistant of all commonly used specialty alloys.
• Sulfuric Acid: Good resistance to sulfuric acid concentrations above 80% at moderate temperatures, and deaerated hydrochloric acid at low concentrations.
• Alkalis: Excellent resistance to caustic soda and potash at all concentrations and temperatures up to boiling.
• Stress Corrosion Cracking (SCC): Excellent stress corrosion cracking resistance due to chlorine ions. Exceptional resistance to chloride-induced SCC, generally does not generate stress corrosion cracking in most environments.
• Hydrogen Embrittlement: Good resistance to hydrogen embrittlement when properly processed. Monel 400 shows lower susceptibility to hydrogen embrittlement when galvanically coupled to steel.
• High Temperature Corrosion: In high-temperature steam, corrosion rate less than 0.026 mm/year. Resistant to ammonia and aminate conditions below 585°C.
• Freshwater: Excellent corrosion resistance with minimal pitting or stress corrosion.
• Fluorine Gas: Resistance to fluorine gas due to nickel-copper composition.
• Bimetallic Corrosion: Galvanic corrosion can occur when certain metals, including aluminum, zinc, and iron, are in direct contact with Monel. Using these metals as fasteners or connectors with Monel is generally not advisable. Proper insulation or matching alloys is recommended.

Manufacturing Standards – Monel Socket Head Cap Screws

All Monel socket head cap screws are manufactured and tested to meet the following standards:

We offer surface finishes: passivation (ASTM A967), silver plating (AMS 2410 for anti‑seize), PTFE coating, electropolish, zinc nickel coating, and Xylan coated options. Cleanroom wash and cleanroom packaging available for semiconductor and medical applications per ISO 13485. Full traceability and destructive/non‑destructive testing available (UT, MPI, PMI). Meets ANSI, ASME, ASTM, QS, SAE and AS standards. RoHS and REACH compliant.