Nov 15 2012
Topics Covered
Introduction
Chemical Composition
Physical Properties
Other Designations
Fabrication and Heat Treatment
Annealing
Welding
Forging
Forming
Machinability
Hardening
Applications
Introduction
Super alloys are available in a variety of forms and contain elements in different combinations to obtain a specific result. Iron-based, cobalt-based and nickel-based are the three types of alloys available.
Super alloy 18Cr-2Ni-12Mn™ is a low nickel austenitic stainless steel high in nitrogen content. This super alloy has good corrosion resistance, high strength and fabricability.
The following datasheet provides an overview of super alloy 18Cr-2Ni-12Mn™.
Chemical Composition
The chemical composition of super alloy 18Cr-2Ni-12Mn™ is outlined in the following table.
| Element |
Content (%) |
| Chromium, Cr |
16.5-19.5 |
| Manganese, Mn |
11-14 |
| Silicon, Si |
1 max |
| Carbon, S |
0.15 max |
| Nickel, Ni |
0.5-2.5 |
| Nitrogen, N |
0.2-0.45 |
| Phosphorus, P |
0.06 max |
| Sulphur, S |
0.03 max |
| Iron, Fe |
Remainder |
Physical Properties
The following table shows the physical properties of super alloy 18Cr-2Ni-12Mn™.
| Properties |
Metric |
Imperial |
| Density |
7.833 g/cm3 |
0.283 lb/in3 |
Other Designations
Equivalent material to super alloy 18Cr-2Ni-12Mn™ includes ASTM A580 (XM-28).
Fabrication and Heat Treatment
Annealing
Super alloy 18Cr-2Ni-12Mn™ is soaked at 1038-1121°C (1900-2050°F) and then rapidly quenched in water or air.
Welding
Super alloy 18Cr-2Ni-12Mn™ can be welded with the commonly used welding techniques including submerged arc welding, gas tungsten arc welding and gas metal arc welding. To obtain resistance to intergranular attack and maximum strength, a filler metal of similar chemical composition should be used.
Forging
Super alloy 18Cr-2Ni-12Mn™ is heated to 1093°C (2000°F), soaked to equalize and finally heated to 1177°C (2150°F) and equalized before forging.
Forming
Super alloy 18Cr-2Ni-12Mn™ can be formed by the commonly used forming methods. Process annealing helps remove the stress evolved due to high work hardening rate of this alloy. For intermediate annealing this alloy is heated to 1065°C (1950°F).
Machinability
Good machining results of super alloy 18Cr-2Ni-12Mn™ can be obtained by ample resulfurized lubricant, slow speeds and positive feeds. This alloy can be machined by all the commonly used machining methods and feeds and speeds similar to those utilized for 317 or 316 stainless. Breakers or curlers can also be used as the chips could be stringy or tough.
Hardening
Super alloy 18Cr-2Ni-12Mn™ cannot be hardened when exposed to thermal treatment and thus requires to be cold worked in order to be hardened.
Applications
Super alloy 18Cr-2Ni-12Mn™ is suitable for use in shafting, communication hardware and fasteners.