Description
Inconel is a family of austenite nickel-chromium-based superalloys.
Inconel alloys are oxidation and corrosion resistant materials well suited for service in extreme environments subjected to pressure and heat. When heated, Inconel forms a thick, stable, passivating oxide layer protecting the surface from further attack. Inconel retains strength over a wide temperature range, attractive for high temperature applications where aluminum and steel would succumb to creep as a result of thermally induced crystal vacancies. Inconel's high temperature strength is developed by solid solution strengthening or precipitation strengthening, depending on the alloy.
Inconel alloys are typically used in high temperature applications. It is sometimes referred to in English as "Inco" . Common trade names for Inconel Alloy 625 include: Inconel 625, Chronin 625, Altemp 625, Haynes 625, Nickelvac 625 and Nicrofer 6020.
Composition
Different Inconels have widely varying compositions, but all are predominantly nickel, with chromium as the second element.
Inconel
Element (% by mass)
Ni
Cr
Fe
Mo
Nb
Co
Mn
Cu
Al
Ti
Si
C
S
P
B
600
72.0
14.0-17.0
6.0-10.0
1.0
0.5
0.5
0.15
0.015
617
44.2-56.0
20.0-24.0
3.0
8.0-10.0
10.0-15.0
0.5
0.5
0.8-1.5
0.6
0.5
0.15
0.015
0.015
0.006
625
58.0
20.0-23.0
5.0
8.0-10.0
3.15-4.15
1.0
0.5
0.4
0.4
0.5
0.1
0.015
0.015
690
59.5
30
9.2
0.35
0.01
0.02
0.35
0.019
0.003
718
50.0-55.0
17.0-21.0
balance
2.8-3.3
4.75-5.5
1.0
0.35
0.2-0.8
0.65-1.15
0.3
0.35
0.08
0.015
0.015
0.006
X-750
70.0
14.0-17.0
5.0-9.0
0.7-1.2
1.0
1.0
0.5
0.4-1.0
2.25-2.75
0.5
0.08
0.01
Alloys of inconel include:
· Inconel 600: Solid solution strengthened
· Inconel 625: Acid resistant, good weldability. The LCF version is typically used in bellows.
· Inconel 690: Low cobalt content for nuclear applications, and low resistivity
· Inconel 713: Newly[when?] developed alloy
· Inconel 718: Gamma double prime strengthened with good weldability
· Inconel 751: Increased aluminium content for improved rupture strength in the 1600 °F range
· Inconel 792: Increased aluminium content for improved high temperature corrosion properties, used especially in gas turbines
· Inconel 939: Gamma prime strengthened to increase weldability
In age hardening or precipitation strengthening varieties, alloying additions of aluminum and titanium combine with nickel to form the intermetallic compound Ni3(Ti,Al) or gamma prime (γ'). Gamma prime forms small cubic crystals that inhibit slip and creep effectively at elevated temperatures.
Complaint
