• Classification of nickel alloys

• Brief introduction

• Nickel alloys are designated by various designation systems however the alloys are usually identified according to their trade names. There are four main groups of nickel alloys: commercially pure nickel alloys, nickel- copper alloys, non-heat-treatable nickel-chromium-iron alloys and heat-treatable nickel-chromium-iron alloys.

• Commercially pure nickel alloys

• These alloys contain not less than 99% nickel.
• Three-digit numbers (2xx, 3xx) are used as trade names of commercial nickel.
• The alloys are characterized by very good corrosion resistance and high ductility.

• Nickel-copper alloys

• These alloys contain about 30% copper, which forms a solid solution with nickel.
• The accepted trade name of Nickel-Copper Alloys is Monel.
• Nickel-Copper Alloy, containing aluminum and titanium as additional alloying elements (Monel K-500), is heat-treatable and may be strengthened by precipitation hardening.

• Non-heat-treatable nickel-chromium-iron alloys

• The major alloying elements of these alloys (15-22% chromium and up to 46% iron) form a solid solution with nickel.
• The alloys may be hardened by cold work.
• The non-heat-treatable Nickel-Chromium-Iron Alloys are identified according to their trade names: Inconel, Incoloy and Hastelloy.

• Heat-treatable nickel-chromium-iron alloys

• These alloys may be strengthened by precipitation hardening due to the presence of additional alloying elements: aluminum, titanium, silicon.
• Nimonic, Inconel X-750, Udimet, Waspaloy, Rene, and Astroloy are some of the trade names of heat-treatable Nickel-Chromium-Iron Alloys.
• Source: http://www.substech.com/dokuwiki/doku.php?id=classification_of_nickel_alloys