Nov 14 2012
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Fabrication and Heat Treatment
Machinability
Forming
Tempering
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 with 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 datasheet provides a detailed description of
super alloy 21-2N valve steel.
Chemical Composition
The following table shows the chemical composition of super
alloy 21-2N valve steel.
| Elements |
Content
(%) |
| Chromium, Cr |
20.35 |
| Manganese, Mn |
8.5 |
| Nickel, Ni |
2.13 |
| Carbon, C |
0.55 |
| Molybdenum, Mo |
0.50 max |
| Silicon, Si |
0.25 max |
Physical Properties
The physical properties of super alloy 21-2N valve steel are
given in the following table.
| Properties |
Metric |
Imperial |
| Density |
7.7 g/cm³ |
0.2878 lb/in³ |
Mechanical Properties
The mechanical properties of super alloy 21-2N valve steel are
displayed in the following table.
| Properties |
Metric |
Imperial |
| Tensile strength |
900-1150 MPa |
13053-16679 psi |
| Modulus of elasticity |
215 GPa |
31183 ksi |
| Elongation |
8% |
8% |
| Reduction |
10% |
10% |
| Hardness |
28 |
28 |
Fabrication and Heat
Treatment
Machinability
Super alloy 21-2N valve steel can be machined similar to that
of the standard 18-8 stainless steels.
Forming
Forming of super alloy 21-2N valve steel can be performed at
950 to 1100ºC (1742 to 2012ºF).
Tempering
Super alloy 21-2N valve steel can be tempered at 730 to 780ºC
(1346 to 1436ºF)
Hardening
Super alloy 21-2N valve steel can be hardened at 1140 to
1180ºC (2084 to 2156ºF) and then water quenched.
Applications
Super alloy 21-2N valve steel finds its application in the
manufacture of automotive valve.