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| HIGH STRENGTH MARAGING STEEL |
CHEMISTRY
| Nominal Analysis | C | Si | Mn | Ni | Co | Mo | Ti | Al | Fe |
| C250 | ,03 max | ,10 max | ,10 max | 18,50 | 7,50 | 4,80 | ,40 | ,10 | Bal. |
| C300 | ,03 max | ,10 max | ,10 max | 18,50 | 9,0 | 4,80 | ,60 | ,10 | Bal. |
| C350 | ,03 max | ,10 max | ,10 max | 18,50 | 12,0 | 4,80 | 1,40 | ,10 | Bal. |
Maraging is a 18% nickel, cobalt strengthened steel (C-type) with excellent properties, workability and heat treatment characteristics. Maraging is double vaccum melted by VIM (Vaccum Induction Melt) followed by VAR (Vaccum Arc Remelt) Maraging material is supplied in the annealed and descaled condition. The alloy is very tough, relatively soft (RC 30/35), readily machined or formed. Maraging provides a high value for critical parts in aerospace, structural, components and tooling applications.
AMS 6512 = C250 maraging
AMS 6514 = C300 maraging
AMS 6515 = C350 maraging
Mil-S-46850 (applies to all grades) – FRACTURE TOUGHNESS APPLIES
Machinability of annealed maraging steels is comparable to steels such as 4340 at the same hardness level (Rc30/35). However, when the material is aged (heat treated), the choice of cutting tools and machining conditions become very important. Rigid equipment, very charp tools and an abundance of coolant are essential.
| C250 | C300 | C350 | ||
| Density | .289 lbs./cu. in. | .289 lbs./cu. in. | .292 lbs./cu. in. | |
| Average Coefficient of Thermal Expansion | 5.6×10-6 in./in./ °F | 5.6×10-6 in./in./ °F | 6.3×10-6 in./in./ °F | |
| Modulus of Elasticity | 27.0×10-6 psi | 27.5×10-6 psi | 29.0×10-6 psi |
HEAT TREATMENT |
Maraging alloys are essentially carbon-free, a protective atmosphere is not required during annealing or aging. Material is supplied in the solution annealed condition with a hardness of 30/35 RC. Typical heat treat time/temperature are listed below. Large cross sections should be aged for longer periods.
| *AGING TEMP | *AGING TIME | *RESULTING HARDNESS | |
| Maraging 250 | 900/925 °F | 6 hrs | 48/52 Rc |
| Maraging 300 | 900/925 °F | 6 hrs | 50/55 Rc |
| Maraging 350 | 900/925 °F | 6 hrs | 55/60 Rc |
| Or 950 °F | 3 hrs | 55/60 Rc |
| TYPICAL – ROUND BAR | |||||
| MINIMUM PROPERTIES | |||||
| AFTER AGING | Rc | TENSILE STRENGTH | ,02% YIELD | ELONGATION | REDUCTION |
| (LONGITUDAL DIRECTION) | KSI | STRENGTH IN 4,5 a% | OF AREA | ||
| 250 | 50 | 254 | 248 | 11,0 | 53 |
| 300 | 54 | 293 | 286 | 10,0 | 46 |
| 350 | 57 | 342 | 336 | 6,2 | 28 |
NOTE: A modified aging cycle is suggested for die casting applications for increased die life. The following thermal treatments have been used to obtain desirable characteristics for die casters. Following the rough machining of the die, anneal at 1500-1525 °F for 1 hour per inch of thickness is typical. After finish machining, an aging heat treatment of 980-1000 °F for 6 hours is typical.
Maraging is available as billet, bar, rod, plate, sheet and customized forgings.
ADVANTAGES OF MARAGING |
*high yield and ultimate tensile strengths
*high toughness, ductility and impact strengths
*high fatigue strength
*high compressive strength
*hardness and wear resistance sufficient for many tooling applications
*high resistance to crack propagation
*readily formed – cold, warm, hot (w/o in process anneals)
*good weldability w/o quenching
*excellent polishability
*low furnace temps required
*precipitation hardening, aging heat treatment
*uniform, predictable shrinkage during heat treatment
*freedom for carburization or decarburization
*through hardening w/o quenching
*minimal distortion during heat treatment (.0009 in/in C250 //.001 in/in C300)
*low coefficient of expansion minimizes heat checking
*pitting and corrosion resistance superior to common tool steel
*good repair weldability
*excellent mechanical properties have led to longer tool life
*easily reworked and retreated for secondary tool life
The technical information, presented in this department are representative only, and are not guaranteed values.