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Nickel
100 th anniversary for Type-B nickel-base ( Ni-Mo ) alloys
Prior to the introduction of the workhorse C-family of nickel-base alloys
( Ni-Cr-Mo ) in the early 1930s , work had been conducted on nickelmolybdenum alloy compositions . This resulted in the award of a patent , in 1921 , for a nickel-molybdenum alloy composition range , which ultimately led to the introduction of Alloy B ( Ni-Mo ) in 1923 with a nickel content of
60 % and nearly 30 % molybdenum .
By Geir Moe , Nickel Institute
B-type alloys possess exceptional resistance to reducing acids , such as hydrochloric , sulphuric , acetic , and phosphoric . Unfortunately , B-type alloys have poor corrosion resistance to oxidising environments . Hence , they are not recommended for use in oxidising media or in the presence of ferric or cupric salts which may cause rapid premature corrosion failure . These salts may develop when hydrochloric acid comes in contact with iron and copper .
Prior to the Second World War , Alloy B was used in supercharger turbine blades in aircraft engines to boost performance and increase horsepower . This application was eventually replaced by other superalloys . Alloy B-2 , introduced in the 1970s , was a modification of the original B composition . It featured reduced silicon and carbon content , to improve thermal stability and resist the formation of grain boundary carbides . This improvement in corrosion resistance was particularly beneficial in the heat-affected zone after welding . The composition was additionally optimised in Type B-3 to further enhance thermal stability and fabrication characteristics and resistance to stress corrosion cracking . Molybdenum primarily provides the corrosion resistance to acidic reducing environments , but it is the nickel-base that provides the foundation for an engineering alloy that can be easily fabricated and welded into industrially useful equipment .
Alloy |
( UNS ) |
Introduction |
Ni |
Mo |
Cr |
Si max |
Fe |
C max |
B |
( N10001 ) |
1923 |
bal |
28 |
1 |
1 |
5 |
0.05 |
B-2 |
( N10665 ) |
1970s |
bal |
28 |
1 |
0.10 |
2 |
0.02 |
B-3 |
( N10675 ) |
1990s |
bal |
28 |
2 |
0.10 |
2 |
0.01 |
Typical composition of the B-family alloys . |
About Nickel Institute
The Nickel Institute is the global association of leading primary nickel producers . Its mission is to advocate for the responsible supply and sustainable development of nickel and the nickel industry . For information , visit nickelinstitute . org
The B-type alloys have been used mainly in hydrochloric and sulfuric acid environments , as well as in acetic , phosphoric , and formic acids . Specific applications include reaction vessels , heat exchangers , valves , pumps , and piping . www . heat-exchanger-world . com Heat Exchanger World February 2024
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