Lecture Notes

Leeb Hardness

This test measures both the impact velocity of a spring loaded impact ball prior to contacting the test surface and the ball's rebound velocity after it has contacted the test surface. The harder the test surface, the larger the rebound velocity, and therefore, the larger the test value.

Application range of impact devices

D type for measuring general pieces

DC type for hole or cylinder

DL type for long and narrow channel or hole

D+15 type for measuring in grooves or recessed surfaces

C type for measuring light and small piece and surface hardened layer

G type for measuring heavy and rough cast and forged piece

E type for very hard material

Impact device D/DC/DL D+15 C G E

Impacting energy 11 Nmm 11Nmm 2.7Nmm 90Nmm 11Nmm

Mass of impacting body 5.5g/5.5g/7.3g 7.8g 3.0g 20g 5.5g

Hardness of spherical test tip 1600HV 1600HV 1600HV 1600HV 5000HV

Diameter of spherical test tip 3mm 3mm 3mm 5mm 3mm

Material of spherical test tip Tungsten carbide Tungsten carbide Tungsten carbide Tungsten carbide Diamond

Diameter of impact device 20mm 20mm 20mm 30mm 20mm

Length of impact device 147/86mm/202mm 162mm 141mm 254mm 155mm

Weight of impact device 75/50g 80g 75g 250g 80g

Max. hardness of the test piece 940/940/950 HV 940HV 1000HV 650HB 1200HV

Average surface roughness of the test piece
Ra :2mm Ra :2mm Ra :0.4mm Ra :7mm Ra :2mm

Min. weight of
test piece Direct measuring 5kg 5kg 1.5kg 15kg 5kg

Stable support 2kg 2kg 0.5kg 5kg 2kg

Compact coupling 0.1kg 0.1kg 0.02kg 0.5kg 0.1kg

Min. thickness
of test piece Compact coupling 3mm 3mm 1mm 10mm 3mm

Min. case hardened depth 0.8mm 0.8mm 0.2mm 1.2mm 0.8mm

Size of
indentation
of spherical
test tip
Hardness
300HV
Indentation diameter 0.54mm 0.54mm 0.38mm 1.03mm 0.54mm

Indentation depth 24mm 24mm 12mm 53mm 24mm

Hardness
600HV Indentation diameter 0.45mm 0.45mm 0.32mm 17mm 0.45mm

Indentation depth 17mm 17mm 8mm 41mm 17mm

Hardness
800HV
Indentation diameter 0.35mm 0.35mm 0.30mm -- 0.35mm

Indentation depth 10mm 10mm 7mm -- 10mm

Impact device			D/DC/DL	D+15	C	G	E
Impacting energy			11 Nmm	11Nmm	2.7Nmm	90Nmm	11Nmm
Mass of impacting body			5.5g/5.5g/7.3g	7.8g	3.0g	20g	5.5g
Hardness of spherical test tip			1600HV	1600HV	1600HV	1600HV	5000HV
Diameter of spherical test tip			3mm	3mm	3mm	5mm	3mm
Material of spherical test tip			Tungsten carbide	Tungsten carbide	Tungsten carbide	Tungsten carbide	Diamond
Diameter of impact device			20mm	20mm	20mm	30mm	20mm
Length of impact device			147/86mm/202mm	162mm	141mm	254mm	155mm
Weight of impact device			75/50g	80g	75g	250g	80g
Max. hardness of the test piece			940/940/950 HV	940HV	1000HV	650HB	1200HV
Average surface roughness of the test piece			Ra :2mm	Ra :2mm	Ra :0.4mm	Ra :7mm	Ra :2mm
Min. weight of test piece	Direct measuring		5kg	5kg	1.5kg	15kg	5kg
	Stable support		2kg	2kg	0.5kg	5kg	2kg
	Compact coupling		0.1kg	0.1kg	0.02kg	0.5kg	0.1kg
Min. thickness of test piece	Compact coupling		3mm	3mm	1mm	10mm	3mm
Min. thickness of test piece	Min. case hardened depth		0.8mm	0.8mm	0.2mm	1.2mm	0.8mm
Size of indentation of spherical test tip	Hardness 300HV	Indentation diameter	0.54mm	0.54mm	0.38mm	1.03mm	0.54mm
	Hardness 300HV	Indentation depth	24mm	24mm	12mm	53mm	24mm
	Hardness 600HV	Indentation diameter	0.45mm	0.45mm	0.32mm	17mm	0.45mm
	Hardness 600HV	Indentation depth	17mm	17mm	8mm	41mm	17mm
	Hardness 800HV	Indentation diameter	0.35mm	0.35mm	0.30mm	--	0.35mm
	Hardness 800HV	Indentation depth	10mm	10mm	7mm	--	10mm