DATA SHEET

LESCALLOY 300M-HS VAC-ARC
HIGH STRENGTH ALLOY STEEL

Typical Composition

C 0.42

Mn 0.75

Si 1.65

Ni 1.80

Cr 0.80

Mo 0.40

V 0.07

GENERAL CHARACTERISTICS

LESCALLOY 300M-HS VAC-ARC steel is a modified 4340 steel with added silicon allowing for use of
a higher tempering temperature. The steel has high hardenability and strength with good ductility and toughness in heavy sections, which make it suitable for aircraft landing gear, flap tracks, and other structural components. This variant has been developed for applications requiring 287 ksi (1979 MPa) minimum tensile strength through stringent control of chemistry and processing parameters. The enhanced properties of Lescalloy 300M-HS VAC-ARC permit the design of lighter aircraft components that exhibit equivalent load carrying capacities compared to standard 300M components. Vacuum arc remelting (VAR) is used to provide optimum cleanliness and preferred ingot structure.

PHYSICAL PROPERTIES

Density: 0.283 lb/in3 (7.84 g/cm3) Thermal Conductivity: 260.0 Btuin/hrftF (37.49 W/mK) Specific Heat: 0.107 Btu/lbF (448J/kgK) Mean Coefficient of Thermal Expansion 0-200F (-17.8-93C): 6.3x10-6 in/inF (11.34x10-6 mm/mmC)

WORKABILITY

Forging: Forge at 1950-2250F (1066-1232C) using a minimum forging temperature of approximately 1700F (927C). Weldability: This steel can be welded by gas or arc fusion methods. Machinability: For optimum machinability, Lescalloy 300M Vac-Arc steel should be normalized and tempered. Approximately 1200F (649C) is suggested for the temper. Hardness: Typically HBW 241-285.

HEAT TREATMENT

Normalize: 1700F (927C), 1 hour, air cool Austenitize: 1600F (871C), 1 hour, oil quench Temper: 500-600F (260-316F), four hours, air cool
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MECHANICAL PROPERTY DATA

TYPICAL TRANSVERSE MECHANICAL PROPERTIES WITH 575F (302C) TEMPER Size Tested in mm 26 - - 305 Specimen Size 0.252 0.252 U.T.S. ksi MPa 0.2% Y.S. ksi MPa Elongation (%) R of A (%) 31 34
FRACTURE TOUGHNESS PER ASTM E 399
At nominal strength levels, the ASTM E 399 plane-strain fracture toughness is typically 60-70 ksi in. (6677 MPa m).
JOMINY END QUENCH HARDENABILITY
2 59.58.5 Distance from Quenched End (1/16 inch) 58.5 58.0 58.0 57.5 57.5 57.57.57.5

Rockwell C

SPECIFICATIONS
Lescalloy 300M-HS VAC-ARC meets the requirements of the specifications below. Contact your Latrobe Specialty Steel sales representative for inquires regarding other specifications. AMS 6419 MTL-1201 (Messier-Dowty) LGMS 1000 (Goodrich)

Hardness Rockwell C

TEMPERING CURVE
Austenitized 1600F (871C), Oil Quench Tempered Twice 2+2 hours
Tempering Temperature C 649
1000 Tempering Temperature F
Latrobe, Pennsylvania 15650-0031 U.S.A. Phone: (724) 537-7711 Fax: (724) 532-6316 www.latrobesteel.com