Incoloy Alloy 20 (UNS N08020)

Incoloy Alloy 20 (also specified as UNS N08020 / Alloy 20 / N08020) is an austenitic nickel-iron-chromium alloy with additions of molybdenum and copper. It was originally developed for use in sulfuric-acid service and offers excellent general corrosion resistance, outstanding resistance to stress-corrosion cracking, and good pitting / crevice-corrosion resistance in chloride-bearing environments. It is widely regarded as a workhorse alloy for corrosive chemical processing.

Overview

• Category: Austenitic Ni-Fe-Cr corrosion-resistant alloy (often grouped with the Incoloy / Alloy 20 family)
• Standards: ASTM B463, B729, B751, B775, B829; ASME SB-463, SB-729, SB-751, SB-775, SB-829; AMS 5582; UNS N08020
• Available forms: Round bar / rod, plate, sheet, pipe & tube, wire, forgings, and custom profiles to order

Chemical Composition (wt%)

Physical Properties

Mechanical Properties (typical, solution-annealed)

Reasonable strength and toughness are retained at moderately elevated temperatures.

Fabrication & Welding

• Hot working: 1050–1200 °C with uniform heating; air cool or water cool after working.
• Cold working: Good cold-formability (cold rolling, cold drawing, stamping), with a moderate work-hardening rate.
• Welding: Good weldability by GTAW (TIG), electron-beam welding, resistance welding and other conventional processes. No preheat is required, and post-weld heat treatment is generally unnecessary.

Heat Treatment

• Solution treatment: Heat to 1038–1107 °C and cool rapidly, to fully dissolve alloying elements into the matrix and maximise corrosion resistance and toughness.
• Stress-relief annealing: Heat to 704–816 °C and air-cool, to relieve residual fabrication stresses.

Key Features

• Good corrosion resistance in sulfuric, phosphoric and nitric acid service;
• Excellent resistance to chloride stress-corrosion cracking;
• Good pitting and crevice-corrosion resistance;
• Reasonable high-temperature strength and oxidation resistance;
• Good fabricability into a wide variety of components.

Corrosion Resistance

• Resists a wide range of inorganic and organic acids, particularly sulfuric acid;
• Strong pitting and crevice-corrosion resistance in chloride-bearing solutions;
• Stable performance in both reducing and oxidising environments.

Typical Applications

• Chemical industry: reaction vessels, heat exchangers, piping and valves handling corrosive chemicals;
• Petrochemical: refinery and chemical plant equipment such as distillation and absorption towers;
• Food processing: corrosion-resistant, non-toxic food-processing equipment;
• Pharmaceutical: equipment and piping that must prevent product contamination.

For detailed datasheets, mill certificates (EN 10204 3.1) or inquiries on specific sizes and tolerances, please contact our sales & engineering team.