Hastelloy C-4/UNS N06455/W. Nr. 2.4610/Alloy C-4 bar

Hastelloy C-4 bar, designated as UNS N06455, material number W.Nr. 2.4610, and commonly known as Alloy C-4, is a nickel-chromium-molybdenum alloy specifically engineered for exceptional thermal stability and corrosion resistance in high-temperature, aggressive chemical environments. This bar stock form is particularly valued for its superior resistance to stress-corrosion cracking and its ability to maintain ductility and corrosion resistance after exposure to temperatures in the range of 650°C to 1050°C (1200°F to 1920°F), making it ideal for components in chemical processing and pollution control equipment.

Introduction to Hastelloy C-4 (Alloy C-4)

Hastelloy C-4 was developed as a low-carbon, low-silicon, and stabilized version of earlier C-type alloys to overcome sensitization issues during welding or high-temperature service. Its composition is balanced to minimize the formation of detrimental secondary phases, ensuring excellent structural stability and corrosion resistance even after prolonged thermal exposure. The bar stock is a key material for machining heat exchanger parts, reactor internals, and furnace components that must withstand both corrosive media and high temperatures.

Chemical Composition of Hastelloy C-4 Bar

The corrosion resistance and thermal stability of Hastelloy C-4 bar are a direct result of its carefully controlled, low-impurity chemistry. Supplied by Shanghai NC Metal Materials Co., Ltd., the bar stock adheres to stringent international standards to guarantee performance in demanding applications.

Mechanical Properties of Hastelloy C-4 Bar

Hastelloy C-4 bar provides a good combination of strength and ductility, particularly notable for its retention of toughness after high-temperature aging. It is typically supplied in the solution-annealed condition.

Physical Properties of Hastelloy C-4 Bar

The physical properties of Alloy C-4 bar are important for design calculations in thermal and chemical processing systems.

Standard Specifications, Bar Forms, and Available Sizes

Shanghai NC Metal Materials Co., Ltd. supplies Hastelloy C-4 bar in forms suitable for machining components for the chemical process and nuclear industries.

Primary Applications of Hastelloy C-4 Bar Stock

Machined components from Hastelloy C-4 bar are used in severe service conditions: Chemical Processing: Reactor internals, distillation column components, heat exchanger tubesheets, and pump shafts handling hydrochloric acid, sulfuric acid, and chlorine-containing environments. Pollution Control: Scrubber components, ducting, and fasteners in flue gas desulfurization (FGD) systems. Nuclear Fuel Reprocessing: Components exposed to hot nitric acid and other aggressive media, where its low cobalt content and thermal stability are critical. Waste Incineration: Heat exchanger and boiler parts in waste-to-energy plants.

Corrosion Resistance and Thermal Stability

Hastelloy C-4 offers outstanding resistance to a wide range of corrosive media. It excels in both oxidizing and reducing acids, including sulfuric, hydrochloric, and phosphoric acids. Its high molybdenum content provides excellent resistance to pitting and crevice corrosion in chloride solutions. A defining characteristic is its exceptional thermal stability; it resists the formation of intermetallic phases and carbides during prolonged exposure in the 650-1050°C range, thereby maintaining its ductility and corrosion resistance where other alloys may embrittle.

Machining and Fabrication of Hastelloy C-4 Bar

Hastelloy C-4 bar is machinable using standard techniques for nickel-molybdenum alloys, though its work-hardening tendency requires attention. Recommendations include: using rigid, powerful machine tools; sharp carbide tools with positive rake angles; moderate cutting speeds; consistent, positive feed rates to minimize work hardening; and high-pressure coolant for heat dissipation and chip control. Its relatively high hardness in the annealed condition compared to other nickel alloys can result in higher tool wear.

Welding of Hastelloy C-4 Bar

Alloy C-4 is designed for excellent weldability with minimal risk of sensitization. It can be welded using Gas Tungsten Arc Welding (GTAW/TIG), Shielded Metal Arc Welding (SMAW/Stick), and Gas Metal Arc Welding (GMAW/MIG). Matching filler metals (e.g., ERNiCrMo-7) are recommended. Due to its extremely low carbon and silicon content and titanium stabilization, the alloy is highly resistant to the formation of grain boundary carbides and harmful phases in the weld heat-affected zone (HAZ), making post-weld heat treatment often unnecessary for corrosion resistance.

Reference Pricing and Key Purchasing Factors

The price of Hastelloy C-4 bar from Shanghai NC Metal Materials Co., Ltd. is influenced by its high nickel and molybdenum content, the cost of stringent impurity control (low C, Si), and its specialized application field.