51CrV4 / 1.8159 Spring Steel

51CrV4 / 1.8159 Spring Steel is chromium vanadium type spring steel. It’s a similar alloy steel to 5150 steel with small, but effective, vanadium addition, to import greater hardness.  51CrV4 / 1.8159 Spring Steel has low distortion properties and is easily heat treated. 51CrV4 / 1.8159 Spring Steel grade is suitable for oil hardening and tempering.

51CrV4 / 1.8159 Spring Steel is usually supplied in the as rolled condition. When used in the oil hardened and tempered condition  51CrV4 / 1.8159 Spring Steel combines spring characteristics with excellent resistance to both abrasion and shock. Hardened  51CrV4 / 1.8159 Spring Steel offers excellent toughness and shock resistance which make it a suitable alloy spring steel for parts exposed to stress, vibration and shock.

51CrV4 / 1.8159 Spring Steel Supply Range

51CrV4 / 1.8159 Spring Steel Round Bar: diameter 8mm – 1000mm
51CrV4 / 1.8159 Spring Steel Square Bar: 20mm – 500mm
Surface Finish: Black, Rough Machined, Turned or as per given requirements.

51CrV4 / 1.8159 Spring Steel Specification and Relevant Standards

Country	USA	BS	Japan	China
Standard	ASTM A29	EN 10083	JIS G4801	GB/T 3077
Grades	6150	1.8159/51CrV4	SUP 10	50CrVA

51CrV4 / 1.8159 Spring Steel Chemical Composition per EN 10083-3 (Spring Steel)

GRADE	NUMBER	C	Si	Mn	P	S	Cr	V
51CrV4	1.8159	0.47-0.55	≤ 0.40	0.70-1.10	≤ 0.025	≤ 0.025	0.90-1.20	0.10-0.25

51CrV4 / 1.8159 Spring Steel Mechanical Properties

Properties		Conditions
		T (°C)	Treatment
Density (×1000 kg/m3)	7.7-8.03	25
Poisson’s Ratio	0.27-0.30	25
Elastic Modulus (GPa)	190-210	25
Tensile Strength (Mpa)	667.4	25	annealed at 815℃
Yield Strength (Mpa)	412.3
Elongation (%)	23.0
Reduction in Area (%)	48.4
Hardness (HB)	197	25	annealed at 815℃
Impact Strength (J)	27.4	25	annealed at 815℃

Forging of Material 51CrV4 / 1.8159 Spring Steel

51CrV4 / 1.8159 Spring Steel could be forged between 2150 and 1600ºF (1175 and 870ºC.) The alloy should be slow cooled after forging or transferred to a furnace around the ‘finishing’ temperature. Do not forge below 840°C.

51CrV4 / 1.8159 Spring Steel Heat Treatment

• Preheat:

1200-1250F (650-675ºC), equalize.

• Annealing:

1100-1300F (595-740ºC), hold 2 hours, air cool. As with 5150 alloy, the microstructure for this 51CrV4 / 1.8159 Spring Steel to give optimum machinability is one of coarse lamellar pearlite to coarse spheroidite.

• Normalizing:

A nominal normalizing temperature for the 51CrV4 / 1.8159 Spring Steel is 1650ºF (900ºC.) This treatment is followed by air cooling.

• Straightening:

Best done warm 400-800F (205-425ºC).

• High Heat:

1550-1650F (845-900ºC), soak 10 to 30 minutes. For vacuum hardening, use the high side of the high heat range and soak times.

• Quenching:

Oil quench to hand warm, 150F (65ºC). Temper 51CrV4 / 1.8159 Spring Steel immediately. Note vacuum furnaces must have oil quench capability.

• Tempering:

Tempering at 400-1200 (205-650ºC) for 1 hour per inch (25mm) of thickness at temperature is recommended. (2 hours min.). Air cool to room temperature. Tempering of the 51CrV4 / 1.8159 Spring Steel will be between 400-600°C for most applications.

Machinability of 51CrV4 / 1.8159 Spring Steel

51CrV4 / 1.8159 Spring Steel is readily machined from a coarse pearlite to a coarse spheroidite microstructure. The machinability rating of 51CrV4 / 1.8159 Spring Steel is 59.

Welding of 51CrV4 / 1.8159 Spring Steel Materials

51CrV4 / 1.8159 Spring Steel can be welded, however, preheating and post weld stress relieving have to be performed for welding this steel.

Welding of 51CrV4 / 1.8159 Spring Steel should be carried out in the annealed condition, not on hardened and tempered material.

Application of 51CrV4 / 1.8159 Spring Steel

It’s commonly used in heavily stressed machinery parts including shafts, gears, pinions and also in hand tool components. 51CrV4 / 1.8159 Spring Steel is also widely in the motor vehicle industry 51CrV4 / 1.8159 Spring Steel is suitable for many general engineering applications that require high tensile strength and toughness.