Nickel
based alloys are very useful materials for the manufacture of high
quality tubing products. One of the key reasons is that they offer
excellent corrosion resistance in both aqueous and high temperature
applications.
Nickel\'s
high degree of corrosion resistance is due to the fact that it is a
relatively noble metal within the galvanic electrochemical series of
metals.
Adding
chromium, molybdenum, copper and other elements to the alloys gives
them an even higher resistance to oxidation and corrosion which makes it
possible to use them in a wider range of applications. Seamless tubes
and pipes made of corrosion resistant nickel alloys are the first choice
for a lot of applications due to their excellent resistance to various
acids (sulphuric acid, hydrochloric acid, phosphoric acid) and alkaline
solutions.
A
further increase of specific alloy elements (such as chromium,
molybdenum, tungsten, titanium, aluminium, niobium, etc.) improves the
high temperature, high strength characteristics of austenitic steels.
The disadvantage of austenitic stainless steels occurs in the fact that
these elements have a reduced solubility. In order to compensate this
effect and to reach the desired result, the nickel concentration can be
increased. The highest alloyed types of high temperature nickel based
alloys contain only a very low iron concentration.
Nickel
based alloys have a higher ability to accept alloying elements in solid
solution than other stainless steel or iron-based alloys. They can
therefore maintain higher metallurgical stability. The combination of
high alloying with multiple elements can provide very good corrosion
resistance in a wide range of environments while still maintaining good
welding and forming characteristics.
