1. Introduce
– A low carbon precipitation strengthened Ni alloy, mainly composed of Fe, Ni, Co and Mo
– Excellent tensile strength in the temperature range of 430~490℃
– Yield strength in excess of 1655 MPa can be obtained by low temperature heat treatment
– Not much difference between tensile strength and yield strength
– 18Ni, Maraging C250, Vascomax 250
– UNS K92890
* Maraging
- Precipitation hardening treatment with extremely low carbon concentration of martensite followed by aging treatment to improve mechanical properties
- Martensite + Aging = Maraging steel
- Large amount of Ni added to facilitate martensite transformation
- Steel with Co and Mo added to Ni alloy to strengthen precipitation of intermetallic compounds
- In maraging steel, C has a great influence on strength, and even a very small amount of C content can greatly improve the strength of martensite
- Generally, there are Maraging 200, 250, 300, 350, and the higher the grade, the more Co and Ti are added
* 250 : Means minimum tensile strength (ksi) of Maraging 250 (250ksi*6.9=1715MPa)
* 18Ni : It means Ni contains 18%
* UNS
- Abbreviation of Unified Numbering Systems for Metals and Alloys
- Unified numbering system for metals and alloys
- A representative number that is compatible with metals and alloys defined in many material-related codes such as ASTM, AISI, ASME, AWS, etc.
* K : Miscellaneous steels and ferrous alloys
2. Property
– High strength, toughness, corrosion and crack resistance, good weldability
| Element | Impact |
|---|---|
| Ni | Provides excellent strength and corrosion resistance |
| Co | Precipitation strengthening element, provides strength, creep properties |
| Mo | Precipitation strengthening element, provides strength, high temperature creep properties |
[Maraging 250 Chemical Composition (%)]
| Ni | Fe | C | Al |
|---|---|---|---|
| 17.00 ~ 19.00 | 66.39 ~ 71.05 | Max. 0.03 | 0.05 ~ 0.15 |
| Ti | Si | Mn | Mo |
|---|---|---|---|
| 0.30 ~ 0.50 | Max. 0.10 | Max. 0.10 | 4.60 ~ 5.20 |
| S | Co | Zr | P |
|---|---|---|---|
| Max. 0.01 | 7.00 ~ 8.50 | Max. 0.01 | Max. 0.01 |
[Maraging 250 Mechanical Properties]
| Tensile Strength (Mpa) | Yield Strength (Mpa) | Elongation (%) |
|---|---|---|
| Min. 1758 | Min. 1724 | 6 |
[Maraging 250 Physical Properties]
| Density (g/㎤) | Melting Range (℃) | Specific Heat (0-100℃), J/kg*℃ |
|---|---|---|
| 8.00 | 1413 | 293 |
3. Standard & Specification
– UNS K92890
| Product Form | AMS |
|---|---|
| Bar, Rod | 6512 |
| Plate, Sheet, Strip | 6520 |
| Pipe | 6512 |
| Wire | 6501 |
4. Available Form
– Bar, Rod
– Plate, Sheet, Strip
– Pipe, Tube : Seamless, Welded
– Wire : Welded, Spring
5. Application & Product
– Aerospace
| Application | Product |
|---|---|
| Aerospace | Missiles, Rocket Motor Cases, Aircraft Landing Gear, Pressure Vessels, Fasteners, Shafts |
(1) Missiles / (2) Rocket Motor Cases / (3) Aircraft Landing Gear / (4) Pressure Vessles
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