The Hastelloy B2 is an alloy containing nickel and molybdenum and strengthened with solid
solution under extremely reducing conditions. With a significantly lower content of carbon, iron
and silicon makes this alloy less prone to decreased corrosion resistance in the welding zone. As
far as the issues of fabrication are concerned, using the other alloying elements containing
chromium and iron resolved the issues to a great extent. However, strong chemistry control
followed by the other measures of development has resulted in what you get today from this
superalloy. Quite naturally, the superalloy that is used today with its limited chemistry can be
widely used in the welded condition and is less prone to stress corrosion cracking under several
conditions. It must never be used in the temperatures ranging from 1000 to 1600 degrees
Fahrenheit as it tends to form secondary phases thereby reducing the ductility of the material.
Use of the nickel-molybdenum alloy
This alloy is widely used in high temperature and reducing acids. The molybdenum content of
this alloy makes it an ideal choice to resist general corrosion under the effect of reducing acids.
Due to the nickel content of hastelloy bar alloy, it also become highly resistant to stress corrosion
cracking in the hot and concentrated solutions of chlorine. When tested under the same
condition, this alloy did not develop any crack although the ductility can be reduced due to the
transformation of the solid phase. It can also develop damage due to intergranular stress
corrosion cracking in those regions that are affected by heat under the effect of organic
solvents comprising of sulfuric acid. This alloy has also shown sensitivity to transgranular stress
corrosion cracking.
Corrosion resistance of Hastelloy B2
Due to the high molybdenum content of this material, it is extremely resistant to hydrochloric
acid used at different concentration and over a wide range of temperatures. It also shows
reasonably good resistance to hydrogen chloride, phosphoric and sulfuric acid. When it comes
to dealing with pitting and stress corrosion cracking in the heat-affected zones, the result is
excellent. It is necessary not to use this alloy in the oxidizing media as it shows little or no
results in those environments.
Recommendation and use
The B2 alloy must never be used in the presence of cupric and ferric salts as it may cause failure
to corrosion. You will note the development of these salts when hydrochloric acid comes into
contact with copper and iron. While using this alloy in combination with copper and iron piping
in a system containing hydrochloric acid, the presence of these salts can reduce the cracking
resistance capability of this alloy and it can fail to provide the necessary protection. The
exposure of B2 alloy to the oxidizing gases must not increase beyond 1000 degrees Fahrenheit
and in the reducing gases the temperature is not to exceed 1600 degrees Fahrenheit. On the
basis of limited tests, it is easy to find out that the corrosion resistance of this alloy is not
affected when kept in twenty percent boiling hydrochloric acid followed by cold reductions of
about fifty percent. Clearly, when determining the stress-resistant capability of the alloys, the
choice is to be made according to the industrial use.
solution under extremely reducing conditions. With a significantly lower content of carbon, iron
and silicon makes this alloy less prone to decreased corrosion resistance in the welding zone. As
far as the issues of fabrication are concerned, using the other alloying elements containing
chromium and iron resolved the issues to a great extent. However, strong chemistry control
followed by the other measures of development has resulted in what you get today from this
superalloy. Quite naturally, the superalloy that is used today with its limited chemistry can be
widely used in the welded condition and is less prone to stress corrosion cracking under several
conditions. It must never be used in the temperatures ranging from 1000 to 1600 degrees
Fahrenheit as it tends to form secondary phases thereby reducing the ductility of the material.
Use of the nickel-molybdenum alloy
This alloy is widely used in high temperature and reducing acids. The molybdenum content of
this alloy makes it an ideal choice to resist general corrosion under the effect of reducing acids.
Due to the nickel content of hastelloy bar alloy, it also become highly resistant to stress corrosion
cracking in the hot and concentrated solutions of chlorine. When tested under the same
condition, this alloy did not develop any crack although the ductility can be reduced due to the
transformation of the solid phase. It can also develop damage due to intergranular stress
corrosion cracking in those regions that are affected by heat under the effect of organic
solvents comprising of sulfuric acid. This alloy has also shown sensitivity to transgranular stress
corrosion cracking.
Corrosion resistance of Hastelloy B2
Due to the high molybdenum content of this material, it is extremely resistant to hydrochloric
acid used at different concentration and over a wide range of temperatures. It also shows
reasonably good resistance to hydrogen chloride, phosphoric and sulfuric acid. When it comes
to dealing with pitting and stress corrosion cracking in the heat-affected zones, the result is
excellent. It is necessary not to use this alloy in the oxidizing media as it shows little or no
results in those environments.
Recommendation and use
The B2 alloy must never be used in the presence of cupric and ferric salts as it may cause failure
to corrosion. You will note the development of these salts when hydrochloric acid comes into
contact with copper and iron. While using this alloy in combination with copper and iron piping
in a system containing hydrochloric acid, the presence of these salts can reduce the cracking
resistance capability of this alloy and it can fail to provide the necessary protection. The
exposure of B2 alloy to the oxidizing gases must not increase beyond 1000 degrees Fahrenheit
and in the reducing gases the temperature is not to exceed 1600 degrees Fahrenheit. On the
basis of limited tests, it is easy to find out that the corrosion resistance of this alloy is not
affected when kept in twenty percent boiling hydrochloric acid followed by cold reductions of
about fifty percent. Clearly, when determining the stress-resistant capability of the alloys, the
choice is to be made according to the industrial use.
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