UNS K93540 / AMS 6515 Maraging 350(18Ni350)
Products Description
Maraging 350 (18Ni350 / C350) is the highest-strength grade in the 18Ni maraging steel series; it achieves a tensile strength of approximately 2400 MPa through a high-cobalt, high-titanium composition while maintaining good toughness and dimensional stability.
Applicable Standards and Available Product Forms
This specification covers a premium aircraft-quality steel in the form of bars, forgings, mechanical tubing, and flash-welded rings up to 5.000 inches (127.00 mm), inclusive, in diameter or least distance between parallel sides, and stock of any size for forging or flash-welded rings.
Maraging 350 is available in the forms of bars, forgings, plates, sheets, seamless tubing, welded tubing, wire, and rings.
Purchasing Note：
When placing an order, it is recommended to clearly specify UNS K93540 / AMS 6515, along with the specific dimensions and delivery condition (typically solution-annealed).
chemical composition AMS 6515
|
Element
|
Min. | Max. |
|
Carbon
|
-- | 0.03 |
|
Manganese
|
-- | 0.10 |
|
Silicon
|
-- | 0.10 |
|
Phosphorus
|
-- | 0.010 |
|
Sulfur
|
-- | 0.010 |
|
Nickel
|
18.00 | 19.00 |
|
Cobalt
|
11.50 | 12.50 |
|
Molybdenum
|
4.60 | 5.20 |
|
Titanium
|
1.30 | 1.60 |
|
Aluminum
|
0.05 | 0.15 |
|
Chromium
|
-- | 0.50 |
|
Copper
|
-- | 0.50 |
Tensile Properties – Response to Maraging Heat Treatment AMS 6515
|
Nominal
Section Thickness
Millimeters
|
Specimen
Orientation
|
Tensile
Strength
MPa
|
Yield Strength
at 0.2% Offset
MPa
|
Elongation
in 4D or 50mm
%
|
|
Up to 127.00, incl
|
Longitudinal
|
2344 | 2275 | 2.8 |
Note: The yield strength and elongation values are taken from MIL-S-46850. The tensile values are from industry practice. These properties were not independently substantiated using SAE/AMS statistical guidelines.
Key Advantages
Excellent dimensional stability: The hardness of the martensitic structure in the solution-annealed state is only RC 30–35, with an aging-induced deformation of less than 0.1%. This allows complex parts to undergo nearly all machining operations in the soft state, requiring only minimal finishing-or no further processing at all-after aging.
Superior strength-toughness balance: Maraging 350 offers a tensile strength of approximately 2400 MPa and a fracture toughness (KIC) of 35–50 MPa·m¹/². Although its toughness is lower than that of Maraging 250 or 300, it remains outstanding among steels in the same strength class.
Exceptional weldability: No preheating or post-heating is required; joint strength can be restored simply by aging the material after welding.
Excellent performance across a wide temperature range: It retains its tensile strength at temperatures up to 450°C and maintains notch impact toughness at temperatures as low as -50°C.
Procurement Specifications
Standards and Grades: Primary standard AMS 6515, UNS designation K93540, commercial grade Vascomax C350. The standard number must be clearly specified at the time of procurement.
Delivery Condition: Typically supplied in the solution-annealed condition with a hardness of RC 30/35 to facilitate subsequent machining. Ultrasonic inspection reports are available to confirm the absence of internal shrinkage cavities, inclusions, or cracks.
Melting Process: Produced using a VIM + VAR (Vacuum Induction Melting + Vacuum Arc Remelting) dual-vacuum melting process to ensure high purity and consistent performance. Impurity elements (S, P) are strictly controlled; excessive sulfur content significantly reduces fracture toughness.
Lork Group
Marketing Operations Department
Email: layla@lorkgroup.com
WhatsApp: +86 199 3707 5488
Hot Tags: UNS K93540, AMS 6515, Maraging 350,18Ni350,Vascomax C350,Ultra-High Strength Steel,Rocket Motor Cases, Maraging 350 rocket case
You Might Also Like
Send Inquiry