Nov 25 2012
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Fabrication and Heat Treatment
Machinability
Forming
Welding
Cold working
Annealing
Hardening
Applications
Introduction
Super alloys are metallic alloys used at high temperatures above 540ºC (1000ºF) where high surface stability and deformation resistance are mainly required. Three major classes of super alloys include iron-base, nickel-base and cobalt-base alloys. The iron-base super alloys are generally wrought alloys featuring stainless steel technology. Nickel-base and cobalt-base super alloys may be cast or wrought based on its composition or application. Super alloys are commonly forged, rolled to sheet or produced in various shapes. However, highly alloyed compositions are produced as castings.
The following sections will describe in detail about super alloy HASTELLOY(r) H-9M™ alloy, which has resistance to pitting attack and crevice corrosion.
Chemical Composition
The following table shows the chemical composition of super alloy HASTELLOY(r) H-9M™ alloy.
|
Element |
Content (%) |
|
Chromium, Cr |
20.5-23 |
|
Iron, Fe |
17-20 |
|
Molybdenum, Mo |
8-10 |
|
Cobalt, Co |
5 max |
|
Tungsten, W |
1-3 |
|
Manganese, Mn |
1 max |
|
Silicon, Si |
1 max |
|
Phosphorus, P |
0.04 max |
|
Carbon, C |
0.03 max |
|
Sulfur, S |
0.03 max |
|
Nickel, Ni |
Remainder |
Physical Properties
The physical properties of super alloy HASTELLOY(r) H-9M™ are given in the following table.
|
Properties |
Metric |
Imperial |
|
Density |
7.7-8.03 g/cm³ |
0.278-0.290 lb/in³ |
|
Melting point |
1371ºC |
2500ºF |
Mechanical Properties
The mechanical properties of super alloy HASTELLOY(r) H-9M™ are displayed in the following table.
|
Properties |
Metric |
Imperial |
|
Tensile strength |
1158 MPa |
16795 psi |
|
Yield strength |
1034 MPa |
14996 psi |
|
Modulus of elasticity |
190-210 GPa |
27557-30457 ksi |
|
Poisson's ratio |
0.27-0.30 |
0.27-0.30 |
|
Elongation |
15% |
15% |
|
Reduction in area |
53% |
53% |
|
Hardness |
335 |
335 |
Thermal Properties
The thermal properties of super alloy HASTELLOY(r) H-9M™ are displayed in the following table.
|
Properties |
Conditions |
|
T (ºC) |
Treatment |
|
Thermal conductivity |
42.7 W/mK |
100 |
- |
Fabrication and Heat Treatment
Machinability
HASTELLOY(r) H-9M™ 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) H-9M™ can be formed through conventional forming methods.
Welding
Welding of HASTELLOY(r) H-9M™ 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) H-9M™ can be cold worked using standard tooling methods. As plain carbon steels has an ability to produce galling, they are not preferred for forming HASTELLOY(r). Galling can be minimized with the help of heavy duty lubricants.
Annealing
Annealing of HASTELLOY(r) H-9M™ can be performed at 1149ºC (2100ºF) followed by rapid cooling of air and water quenching.
Hardening
HASTELLOY(r) H-9M™ can be hardened by cold working.
Applications
The following are the major applications of HASTELLOY(r) H-9M™:
-
Applications involving stress-cracking or corrosive environments
-
Flue gas desulfurization in electric power industry.