Frequently Asked Questions

What are the main alloying elements and their properties?

Goto CHY to know more.

Aluminium (Al) &#; Strengthening in small amounts, oxidation in the range of 1-5%. It is a ferritiser and so promotes sigma formation.

Boron (B) &#; Strengthening element from 0.-0.005%. It also improves hot workability but decreases weldability.

Cerium (Ce) &#; Improves oxidation resistance, as do the other rare earth elements such as La and Y etc.

Chromium (Cr) &#; Improves corrosion property as it forms protective chromium oxide scale in oxidising media, high-temperature oxidation and sulphidation. Cr also adds strength and carburisation resistance, and promotes sigma formation.

Cobalt (Co) &#; Solid solution strengthener and austenitiser.

Copper (Cu) &#; Improves resistance to salts and reducing acids (i.e. non-aerated sulphuric and hydrophuric acids). If added to Ni-Cr-Mo-Fe alloys, Cu enhances resistance to hydrochloric, phosphoric and sulphuric acids.

Iron (Fe) &#; Present from 0-75% in heat resistant alloys for improved high-temperature mechanical strength and carburisation. It is a ferritising element. Fe helps reduce cost of alloying elements and controls thermal expansion.

Molybdenum (Mo) &#; Solid solution strengthener. However, excessive addition can lead to catastrophic oxidation promoting intermetallic phase formation. It also improves pitting resistance in stainless grades.

Nickel (Ni) &#; Improves metallurgical stability, thermal stability and weldability. There are about 8-80% Ni present in all austenitic heat resistant alloys. It helps reduce sigma formation. Ni also improves resistance to reducing acids and caustics, improving its performance against stress corrosion cracking particularly in chlorides and caustics. Excessive amount of Ni can make an alloy susceptible to sulphidation.

Are you interested in learning more about Nickel Base Alloy? Contact us today to secure an expert consultation!

Niobium (Nb) &#; Strengthener, both as carbide and solid solution. It can be quite detrimental to oxidation resistance at temperature above °C.

Nitrogen (N) &#; Strengthening element added up to about 0.25%, more commonly around 0.15% to high-performance alloys. N is an austenitising element which retards sigma formation.

Silicon (Si) &#; Improves oxidation and carburisation resistance. Si is a ferritiser which promotes sigma formation.

Titanium (Ti) &#; Strengthening element as a carbide former. Hi content of Ti leads to gamma prime formation which are ferritiser and so promoting sigma formation.

Tungsten (W) &#; Solid solution strengthener.

Not all metals can be mixed with nickel, but some of the most common elements are iron, chromium, aluminum, molybdenum, copper, cobalt, and titanium. To make nickel alloys, you&#;d have to follow the same process used for pretty much every other metal alloy. The alloying elements need to be decided on, and their ratios need to be carefully chosen. Once that&#;s done, the elements are all melted together in something like an arc furnace, which also purifies them, and then the alloy is cast into ingots, and off to be formed using either cold or hot processing.

A Brief History

It&#;s believed that the first nickel alloy was used in 200 BCE in China. That&#;s the earliest record available, and the material was referred to as &#;white copper,&#; which experts believe was an alloy of nickel and silver. Fast forward to , A. F. Cronstedt, a German scientist, managed to isolate nickel from the niccolite mineral. Copper and zinc were often found in these first nickel alloys, which came to be known as &#;German silver&#; and weren&#;t really used for anything other than ornaments.

After James Riley made an iron-chromium alloy in , W. H. Hatfield figured out that adding nickel to these alloys would make them incredibly corrosion-resistant. This led to the creation of what we now know as austenitic stainless steel.

Nickel Alloy Characteristics

Here are the main characteristics of nickel alloys:

• Corrosion/oxidation resistant
• High strength
• Heat resistance up to 980°C
• Highly ductile, won&#;t break easily if bent
• Magnetic, can easily be magnetized and demagnetized
• Weldability with various welding methods (although could develop hot or warm cracking and porosity)
• Low thermal conductivity, higher with nickel-copper alloys
• Low electrical conductivity, less than pure copper or silver
• Low thermal expansion coefficient, great for precision
• Varying colors depending on alloying element

It&#;s generally quite hard to differentiate nickel alloys from other types of metals. Nickel alloys can seem slightly dull when their surface is rough, but when it&#;s smooth, they can be shiny and reflective. Here&#;s an example of what copper-nickel alloy rods look like:

Contact us to discuss your requirements of Soft Magnetic Alloy. Our experienced sales team can help you identify the options that best suit your needs.