Incoloy 28/Alloy 28/N08028/W-Nr.1.4563/Alloy 28 bar

Incoloy 28 bar, also known as Alloy 28, UNS N08028, and W.Nr. 1.4563, is a nickel-iron-chromium alloy with significant additions of molybdenum and copper, specifically engineered for exceptional resistance to sulfuric acid and other aggressive chemical environments, particularly those containing chlorides. This bar stock form is a critical material for machining components such as pump shafts, valve stems, and agitators used in chemical processing, phosphoric acid production, and offshore oil & gas applications where resistance to pitting, crevice corrosion, and stress corrosion cracking is paramount.

Introduction to Incoloy 28 (Alloy 28)

Incoloy 28 is a super-austenitic stainless steel (often classified as a nickel-iron alloy) that bridges the gap between standard stainless steels and high-nickel alloys. Its high chromium, molybdenum, and copper content provide a balanced resistance to both oxidizing and reducing acids, with a special emphasis on sulfuric acid service across a wide concentration and temperature range. The bar stock is ideal for fabricating parts that must withstand wet process phosphoric acid, sulfuric acid condensate, and chloride-laden sour environments.

Chemical Composition of Incoloy 28 Bar

The corrosion resistance of Incoloy 28 bar, particularly to sulfuric acid, is derived from its carefully optimized chemistry. Supplied by Shanghai NC Metal Materials Co., Ltd., the bar stock meets stringent international standards for chemical processing applications.

Mechanical Properties of Incoloy 28 Bar

Incoloy 28 bar offers a good combination of strength and ductility, suitable for structural components in corrosive environments. It is typically supplied in the solution-annealed condition.

Physical Properties of Incoloy 28 Bar

The physical properties of Alloy 28 bar are consistent with other austenitic alloys and are important for equipment design.

Standard Specifications, Bar Forms, and Available Sizes

Shanghai NC Metal Materials Co., Ltd. supplies Incoloy 28 bar in various forms suitable for the chemical process and related industries.

Primary Applications of Incoloy 28 Bar Stock

Machined components from Incoloy 28 bar are essential in specific severe corrosive services: Chemical Processing: Pump shafts, valve trim, and heat exchanger tubes for sulfuric acid production and handling across a wide concentration range (particularly 40-80% H2SO4). Phosphoric Acid Production: Critical components such as agitators, filter equipment, and piping in wet-process phosphoric acid plants where fluorides and chlorides are present. Offshore Oil & Gas: Downhole tubing, Christmas tree components, and fasteners for sour service (H2S/CO2/chlorides) where resistance to sulfide stress cracking is required. Pulp and Paper: Equipment in digesters and bleach plants.

Corrosion Resistance Overview

Incoloy 28 offers a specialized corrosion resistance profile centered on sulfuric and phosphoric acids. Its copper content makes it particularly effective for sulfuric acid service, outperforming many stainless steels and some higher nickel alloys in certain concentration/temperature windows. It provides good resistance to phosphoric acid, including the impurities (fluorides, chlorides) found in wet-process acid. The alloy also exhibits excellent resistance to chloride-induced pitting, crevice corrosion, and stress corrosion cracking, making it suitable for sour gas environments when qualified to standards like NACE MR0175/ISO 15156.

Machining and Fabrication of Incoloy 28 Bar

Incoloy 28 bar is machinable using techniques similar to those for other austenitic stainless steels and nickel alloys. Recommendations include: using rigid machine setups; sharp carbide tools with positive rake angles; moderate speeds and feeds; and ample coolant to control work hardening and heat. Its machinability rating is generally better than that of the high-molybdenum Hastelloy-type alloys but requires more care than standard 300-series stainless steels.

Welding of Incoloy 28 Bar

Alloy 28 is considered weldable by common processes such as Gas Tungsten Arc Welding (GTAW/TIG) and Shielded Metal Arc Welding (SMAW). Matching or over-alloyed filler metals (e.g., ERNiCrMo-3 or ERNiCrMo-4) are typically recommended to maintain corrosion resistance in the weld metal. Due to its moderate carbon content, post-weld heat treatment is not typically required for thin sections, but for heavy weldments in aggressive service, a solution anneal may be specified to restore optimal corrosion resistance.

Reference Pricing and Key Purchasing Factors

The price of Incoloy 28 bar from Shanghai NC Metal Materials Co., Ltd. is influenced by its nickel, chromium, and molybdenum content, as well as its specific application in sulfuric and phosphoric acid service.