Nov 20 2012
Topics Covered
IntroductionChemical CompositionPhysical PropertiesOther DesignationsFabrication and Heat Treatment Machinability Forming Welding Cold working Annealing HardeningApplications
Introduction
Super alloys or high performance alloys have the ability to function at temperatures above 540ºC (1000ºF) with deformation resistance and high surface stability. As they have good oxidation and creep resistance, super alloys can be commonly forged, rolled to sheet or produced in various shapes. Iron-base, nickel-base and cobalt-base alloys are the major types of super alloys. Nickel-base and cobalt-base super alloys may be cast or wrought based on its composition or application. The iron-base super alloys are generally wrought alloys with stainless steel technology. These alloys can be strengthened by precipitation hardening, work hardening and solid-solution hardening.
HASTELLOY(r) G-3 alloy has high tungsten and molybdenum contents, which makes it resistant to corrosion.
The following section will discuss in detail about HASTELLOY(r) G-3 alloy.
Chemical Composition
The following table shows the chemical composition of HASTELLOY(r) G-3 alloy.
| Element |
Content (%) |
| Chromium, Cr |
21-23.5 |
| Iron, Fe |
18-21 |
| Molybdenum, Mo |
6-8 |
| Cobalt, Co |
5 max |
| Copper, Cu |
1.5-2.5 |
| Tungsten, W |
1.5 max |
| Silicon, Si |
1 max |
| Manganese, Mn |
1 max |
| Niobium+Tantalum (Ni+Ta) |
0.5 max |
| Phosphorus, P |
0.04 max |
| Sulfur, S |
0.03 max |
| Carbon, C |
0.015 max |
| Nickel, Ni |
Remainder |
Physical Properties
The physical properties of HASTELLOY(r) G-3 alloy are given in the following table.
| Properties |
Metric |
Imperial |
| Density |
8.3 g/cm³ |
0.3 lb/in³ |
| Melting point |
1343ºC |
2450ºF |
Other Designations
Equivalent materials to HASTELLOY(r) G-3 alloy are the following:
- ASTM B582
- ASTM B619
- ASTM B622
- ASTM B626
- DIN 2.4619
Fabrication and Heat Treatment
Machinability
HASTELLOY(r) G-3 alloy can be machined using conventional techniques employed for iron based alloys. The quality of the alloy can be improved with the utilization of water-base coolants. Heavy duty machining tools and equipment can be used prior to cutting in order to reduce chattering or work-hardening of the alloy.
Forming
HASTELLOY(r) G-3 alloy can be formed through conventional forming methods.
Welding
Welding of HASTELLOY(r) G-3 alloy is performed through commonly used welding techniques like gas tungsten arc welding, shielded metal-arc welding, metal-arc welding and submerged-arc welding. However, an alloy filler metal that suits this alloy should be used.
Cold working
HASTELLOY(r) G-3 alloy can be cold worked using standard tooling methods. As plain carbon steels produce galling, they are not preferred for forming HASTELLOY(r) G-3 alloy. Galling can be minimized with the help of heavy duty lubricants.
Annealing
Annealing of HASTELLOY(r) G-3 alloy can be performed at 1177ºC (2150ºF) followed by rapid cooling of air and water quenching.
Hardening
HASTELLOY(r) G-3 alloy can be hardened by cold working.
Applications
HASTELLOY(r) G-3 alloy finds its application in the manufacture of process equipment for mixed acids, sulfate compounds and flue gas scrubbers.