MARAGING (C) 250 | UNS K92890 | AMS 6512 | ASTM A 538 | Mil-S-46850D | BS S162 | DTD 5212 | MSRR 6551
General
Maraging is a 18% nickel, cobalt strengthened steel (C-type), with excellent mechanical properties, workability and heat treatment characteristics.
Introduction
In comparison with carbon steels, alloy steels are a lot more responsive to mechanical and heat treatments. Alloy steels can be used in specific melting and deoxidization processes for particular applications.
Applications
Typical applications for maraging include missile and rocket motor cases, landing and takeoff gear, munitions, aerospace, extrusion tooling, die casting, high performance shafting, gears and fasteners.
Composition
| Element | Content (%) |
|---|---|
| Iron, Fe | 68 |
| Nickel, Ni | 18.5 |
| Cobalt, Co | 7.5 |
| Molybdenum, Mo | 4.8 |
| Titanium, Ti | 0.4 |
| Aluminum, Al | 0.1 |
| Silicon, Si | ≤ 0.10 |
| Manganese, Mn | ≤ 0.10 |
| Carbon, C | ≤ 0.030 |
| Phosphorous, P | ≤ 0.010 |
| Sulfur, S | ≤ 0.010 |
| Zirconium, Zr | 0.01 |
| Boron, B | 0.003 |
Physical Properties
The following table shows the physical properties of maraging 250 alloy steel.
| Properties | Metric | Imperial |
|---|---|---|
| Density | 8.00 g/cc | 0.289 lb/in³ |
Material Melt Method Maraging melt method is a VIM (Vacuum Induction Melt) + VAR (Vacuum Arc Remelt)
As Shipped Condition Maraging is supplied in the annealed and descaled condition. The alloy is very tough, relatively soft (30/34 Rc), therefore, readily machined and formed.
Mechanical Properties
The mechanical properties of annealed maraging 250 alloy steel are displayed in the following table.
| Properties | Metric | Imperial |
|---|---|---|
| Tensile strength | 965 MPa | 140000 psi |
| Yield strength (@strain 0.200 %) | 655 MPa | 95000 psi |
| Bulk modulus (typical for steel) | 140 GPa | 20300 ksi |
| Shear modulus (estimated from elastic modulus) | 73.0 GPa | 10600 ksi |
| Elastic modulus | 190 GPa | 27600 ksi |
| Poisson’s ratio (calculated) | 0.3 | 0.3 |
| Elongation at break (in gage length of 4.5 times the square root of area) | 17.00% | 17.00% |
| Reduction of area | 75.00% | 75.00% |
| Hardness, Brinell (converted from Rockwell C hardness) | 290 | 290 |
| Hardness, Knoop (converted from Rockwell C hardness) | 311 | 311 |
| Hardness, Rockwell C | 30 | 30 |
| Hardness, Vickers (converted from Rockwell hardness) | 301 | 301 |
Minimum Properties (After Heat Treatment)
- Hardness ……………… Rc 48
- Charpy V-notch ……… 15 ft/lbs
- Reduction of Area ……. 50%
- Elongation ……………. 6.0%
- Yield Strength …………. 240
- ksi Fracture Toughness ….. 75 KIC
Physical Properties
- Density………………………………… .289 lbs./cu. In
- Average Coefficient of Thermal Expansion (70 – 900 F) ……………… 5.6 x 10 -6 in/in. F
Heat Treatment Aging Process (Non Die Casting Applications) Material is to be heat treated to 900 F +/- 10 holding at temperature for 6 hours then cooling at room air temperature. During the aging treatment maraging shrinks uniformly and predictably on all dimensions .0009 in/in
Heat Treatment Aging Process (Die Casting Applications) Following the rough machining of the die, anneal at 1500-1525 F for 1 hour per inch of thickness is recommended. After finish machining , an aging heat treatment of 980-1000 F for 6 hours is recommended.
Machining
Maraging steel in the annealed condition is comparable to 4340. However, when maraging is aged, the type of cutting tool and speeds change. Rigid equipment, firm tool supports, sharp tools and abundant coolant are essential.
Welding
Maraging is weld able without preheat, in both the annealed and aged condition. Only an aging heat treatment is needed to restore in the weld.
Specifications
- AMS 6512
- ASTM A 538
- Mil-S-46850D
- UNS K92890
- Werkstoff Nr. 1.6359
- BS S162
- DTD 5212
- MSRR 6551
- MAT 102
- MIA 101
- Udimar 250
- Vascomax C250
FountainHead Alloys is ISO 9001:2015 approved. © FountainHead Alloys 1996
