Nickel Alloys

Nickel alloys offer a combination of excellent corrosion resistance, strength, toughness, metallurgical stability, fabricability and weldability. Many Nickel alloys additionally posses outstanding heat resistance, making them ideal choice for applications requiring chemical resistance and strength at elevated temperatures.

Nickel alloys represent a step up from conventional stainless steels and superaustenitic iron-based alloys in resisting corrosion by a wide spectrum of acids, alkalis and salts. An outstanding attribute of nickel alloys is exceptional resistance to aqueous solutions containing halide ions. In that regard, nickel alloys are far superior to austenitic stainless steels, which are notoriously prone to attack by wet chlorides and fluorides.

This superior corrosion behavior of nickel alloys manifests itself not only in term of lower metal loss, but in the ability to better withstand localized attack, notably pitting/crevice corrosion, intergranular attack and stress corrosion cracking. These forms of localized attack, more so than general thinning, account for the majority of corrosion-induced failures in the chemical industry.

Nickel alloys owe their corrosion resistance parity to the inherent lower reactivity of nickel relative to iron, as measured by its more noble oxidation potential in the EMF series. Similar to stainless steels, chromium-containing nickel alloys have the capability to passivate.

An added advantage of nickel over iron is the ability to accept fractions of alloying elements without forming bridle phases. Common alloying additions for enhanced corrosion resistance are chromium, molybdenum and copper.

A number of other applications for nickel alloys involve the unique physical properties of special-purpose nickel base or high-nickel alloys. These include:

  1. Heat-resistant applications: Nickel-base alloys are used in many applications where they are subjected to harsh environments at high temperatures. Nickel-chromium alloys or alloys that contain more than about 15% Cr are used to provide both oxidation and carburization resistance at temperatures exceeding 760ºC

  2. Corrosion resistance: Nickel-base alloys offer excellent corrosion resistance to a wide range of corrosive media. However, as with all types of corrosion, many factors influence the rate of attack. The corrosive media itself is the most important factor governing corrosion of a particular metal.

  3. Low-expansion: Nickel was found to have a profound effect in the thermal expansion of iron. Alloys can be designed to have a very low thermal expansion or display uniform and predictable expansion over certain temperature ranges.

  4. Electrical resistance: Several alloys systems based on nickel or containing high nickel contents are used in instruments and control equipment to measure and regulate electrical characteristics (resistance alloys) or are used in furnaces and appliances to generate heat (heating alloys)

  5. Soft Magnetic: The high-nickel alloys (about 79% Ni with 4 to 5% Mo; bal Fe) have high initial permeability and low saturation induction.

  6. Shape memory: Metallic materials that demonstrate to return to their previously shape when subjected to the appropriate heating schedule are referred to as shape memory alloys. Nickel-titanium alloys (50% Ni – 50% Ti) are one of the few commercially important shape memory alloys.

Commercial forms:

  • Pure Nickel: Nickel 200/201:

  • Nickel – Copper Alloys: Alloy 400, Alloy K500

  • Nickel-Chromium and Nickel-Chromium-Iron Alloys: Alloy 600, X750, Alloy 625, Alloy C22, Alloy C276

  • Iron-Nickel-Chromium Alloys: Alloy 800, 800HT,

  • Controlled-expansion alloys: Alloy 902…

Nickel alloys are more expensive than stainless steels. However, economic comparisons on a first-cost, rather tan on a life-cycle basis, can be deceiving. For instance, Ni-Cr-Mo alloys cost roughly five times as much as 18Cr-8Ni stainless steels and about twice as much as super-austenitic stainless steels.

40 years as specialists of the special

Supplying special materials to industry since 1983. Specialists in materials with high corrosion and temperature resistance, adding value to the supply chain making easier the access to needed quantity and delivery time of these high technical complexity materials but necessary in the day to day life of many industries.

During these more than 40 years of history, Acequisa has earned a position as a leader in the distribution of this type of products at a national level. Due to the high quality of our service, our customers have always found us an ally to find the best conditions for the supply of special stainless steels and alloys of nickel, titanium and others.