RAYCHIN LIMITED

Waspaloy Button Head Cap Screws – Design & Configurations

Critical Applications of Waspaloy Button Head Cap Screws

International Standards & Global Designations – Waspaloy Button Head Cap Screws

RAYCHIN LIMITED manufactures Waspaloy button head cap screws from vacuum induction melted (VIM) and vacuum arc remelted (VAR) or electroslag remelted (ESR) material conforming to the most widely used national and international specifications. All material is traceable to the mill.

Chemical Composition (Weight %) – Waspaloy (UNS N07001)

Our Waspaloy button head cap screws are produced from vacuum induction melted (VIM) and vacuum arc remelted (VAR) material conforming to the following limits per AMS 5708, AMS 5544, and ASTM B637 standards.

Waspaloy (UNS N07001) – Nickel-Based Superalloy

Metallurgical note: Waspaloy is a precipitation-hardening nickel-based superalloy strengthened through the formation of gamma prime (γ') phase Ni₃(Al, Ti) in a disordered FCC matrix (γ). The alloy is produced by vacuum induction melting (VIM) and vacuum arc remelting (VAR) or electroslag remelting (ESR) to ensure high purity and consistent properties. High-temperature strength is obtained from solid solution strengthening elements (molybdenum, cobalt, chromium) and aging elements (aluminum, titanium). The alloy maintains excellent strength and stability at temperatures exceeding those of Alloy 718, making it the preferred choice for critical rotating applications up to 650°C (1200°F). Boron content (0.003-0.010%) plays a critical role in creep resistance and ductility at elevated temperatures.

Complete Mechanical & Physical Properties – Waspaloy (MPa / ksi)

Waspaloy button head cap screws are supplied in fully heat-treated condition per AMS specifications. Data represent typical values based on industry standards.

Mechanical Properties – Waspaloy (Fully Heat-Treated Condition)

High-Temperature Mechanical Properties – Waspaloy

Physical Properties – Waspaloy

High‑Temperature Performance of Waspaloy Button Head Cap Screws

Waspaloy is renowned for exceptional high-temperature strength and stability, maintaining useful mechanical properties up to 870°C (1600°F) in oxidizing atmospheres. The alloy can be used at temperatures up to 650°C (1200°F) for critical rotating applications and up to 870°C (1600°F) for simpler applications. Waspaloy exhibits superior strength compared to Alloy 718 at temperatures exceeding 650-705°C (1200-1300°F). The alloy maintains approximately 60% of its room temperature tensile strength at 815°C (1500°F), with yield strength of 517 MPa (75 ksi). Excellent creep resistance under sustained loading at elevated temperatures ensures long-term reliability in gas turbine and aerospace applications. The button head design provides a wide bearing surface for clamping thin materials while maintaining a low profile for clearance-limited applications.

Elevated Temperature Capabilities

High-Temperature Comparison – Waspaloy vs. Alloy 718

Note: Waspaloy excels in applications requiring maximum strength at elevated temperatures, particularly in gas turbine hot sections where alloy 718 would be inadequate. The button head design provides excellent clamping for thin materials while maintaining a low profile.

Exceptional Corrosion Resistance of Waspaloy Button Head Cap Screws

Waspaloy offers outstanding corrosion resistance in high-temperature oxidizing and sulfidizing environments, making it suitable for the most demanding applications in gas turbines, aerospace, and chemical processing. Hot corrosion can be divided into two types: type 1 (815 to 955°C) where salt is in a liquid state, and type 2 (595 to 815°C) where reaction rate can be very high. Waspaloy is designed to operate at high temperatures up to 700°C in aggressive environments, and up to 760°C for hot gas expander components. The smooth button head profile prevents accumulation of corrosive media and facilitates cleaning.

• Oxidation Resistance: Outstanding resistance to scaling and oxidation up to 870°C (1600°F). Performs well in combustion environments and under frequent thermal cycling conditions. Forms protective oxides (Cr₂O₃, Al₂O₃, TiO₂) that provide excellent high-temperature corrosion resistance.
• Sulfidation Resistance: Superior performance in sulfur-containing environments found in gas turbine engine service. Resists attack by sulfur compounds at elevated temperatures. Hot Gas Expander components (blades, discs, rings, vanes) are typically forged in Waspaloy for service up to 760°C in Fluid Catalytic Cracking (FCC) units.
• Hot Corrosion: Good resistance to hot corrosion in the presence of combustion products. The smooth dome head prevents fluid or debris entrapment, enhancing corrosion resistance in harsh environments.
• Salt Spray Environments: Performs well in salt spray environments found in gas turbine engine service. Resistance to NaCl/Na₂SO₄ mixtures at elevated temperatures is excellent.
• Atmospheres: Good performance in atmospheres encountered in gas turbine engine service and combustion environments.
• Solution Treated Condition: Solution treated material offers the best corrosion resistance.
• Bimetallic Corrosion: Can be safely connected to other nickel-based superalloys, stainless steels, and titanium alloys with appropriate precautions.

Manufacturing Standards – Waspaloy Button Head Cap Screws

All Waspaloy button head cap screws are manufactured and tested to meet the following standards:

We offer surface finishes: plain (as-machined), chemical cleaned, passivated. Silver plating per AMS 2410 available for anti‑seize. Controlled solution and precipitation heat treatment processes per AMS 5704/5705 schedules ensure optimal mechanical properties. Standard heat treatment includes solution treatment at 1825-1925°F (995-1080°C), stabilization at 1550°F (845°C)/4 hrs/AC, and age hardening at 1400°F (760°C)/16 hrs/AC. NADCAP accredited heat treatment processes. Specialized heading and thread rolling for accurate button head geometry. Full traceability and destructive/non‑destructive testing available (UT, FPI, MPI). AS9100 and ISO 9001:2015 certified quality management. ISO 13485 certified for medical applications with cleanroom packaging available. Build-to-print specials to customer specifications are available.