Shore scleroscope hardness

A measure of hardness on a scale in which tempered steel is rated 100. Measurements are made by a device (the scleroscope) in which a diamond-pointed hammer falls under its own weight within a graduated, vertical glass tube placed above the material whose hardness is to be measured. When the hammer strikes the material it bounces off. The height of the rebound was taken as a measure of the hardness of the surface. The tube was graduated in “shore units.” A.F. Shore invented the device and the Shore Instrument & Manufacturing Company made it.

The advantages of the Shore scleroscope were that it was portable, a workman could easily be trained to use it, and it was cheap relative to other instruments for measuring hardness. In the late 20th century, however, it gradually fell out of use.

The Shore scleroscope should not be confused with the Shore durometer, which measures indentation and is used for testing rubbers and plastics.

1910 patent drawing of sclerometer

sources

1

Shore Scleroscope Hardness. — Height of rebound of diamond pointed hammer falling by its own weight on the object. The hardness is measured on an empirical scale on which the average hardness of martensitic high carbon steel equals 100. On very soft metals a “magnifier” hammer is used in place of the commonly used “universal” hammer and values may be converted to the corresponding “universal” value by multiplying the reading by 4/7. The scleroscope hardness, when accurately determined, is an index of the tensile elastic limit of the metal tested.

Frederick E. Fowle.
Smithsonian Physical Tables, 7th revised edition, reprint.
Smithsonian Miscellaneous collections, vol. 71, no. 1.
Washington, DC: Smithsonian Institution, 1921.
Page 74.

2

Substance     Scleroscope
Aluminum 99%+ rolled sheet, hard,
not annealed
14
sand cast at 700°C 4 - 5
sheet annealed
at 200°C for 2 hours
8
sheet annealed
at 300°C for 2 hours
4.5
sheet annealed
at 400°C for 2 hours
4.5
sheet annealed
at 200°C for 30 minutes
11.8
sheet annealed
at 400°C for 30 minutes
4.5
Aluminum + copper "alloy No. 12",
92% Al, 8% Cu
sand cast 15 - 18
Aluminum + copper +
magnesium
95.2% Al, 4.2% Cu, 0.6% Mg cast at 700°C 17 - 18
annealed at 500°C 21
Aluminum + copper + nickel +
magnesium + manganese
93.5% Al, 3.5% Cu,
1.5% Ni, 1% Mg, 0.5% Mn
cast at 700°C 9 - 25
Aluminum + copper +
 nickel + manganese
94.2% Al, 3% Cu,
2% Ni, 0.8% Mn
cast at 700°C 9 - 27
Aluminum + zinc + copper 88.2% Al, 3% Cu,
8.4% Zn
cast at 700°C 10
annealed at 500°C 10
81.1% Al, 3% Cu,
15.9% Zn
cast at 700°C 15
annealed at 500°C 15
Brass 90% Cu, 10% Zn
(red metal)
cold rolled hard 20
cold rolled soft 10
80% Cu, 20% Zn
(low brass, bell metal)
cold rolled hard 28
cold rolled soft 12
66% Cu, 34% Zn
(standard sheet)
cold rolled hard 26
cold rolled soft 12
Bronze 90% Cu, 10% tin
(gun bronze or bell metal)
cast 23
90% Cu, 10% Al
(aluminum bronze)
cast 25 -26
92.5% Cu, 7.2% Al
(aluminum bronze)
rolled and annealed 19
58% Cu, 39% Zn, 0.05% Mn
(manganese bronze)
sand cast 18 - 19
Copper 99%+ annealed at 200°C 7
cast 8
rolled, annealed at 500°C 6
cold drawn, 50% reduction 18
Gold pure cast 20
Lead   cast 3
Nickel 98.5% commercial wrought 35
Platinum   drawn hard 24
drawn annealed 13
Silver pure drawn hard 32
Tin 99.8% cast 8
Steel, carbon SAE 1010 annealed 18
ht A 24
SAE 1020 annealed 17
ht H, 230°C 35
SAE 1045 annealed 27
ht H, 260°C 45
SAE 1095 annealed 29
ht F, 510°C 75
Steel, nickel SAE 2315 ht H 43
SAE 2335 ht H 62
SAE 2345 ht H 76
Steel, nickel chrome SAE 3120 annealed 22
ht H, 450°C 36
SAE 3135 annealed 30
ht H or D 44
SAE 3220 ht H or D 50
SAE 3250 ht M 64
SAE 3320 ht L 50
SAE 3340 ht P 64
Steel, chromium SAE 51120 ht M or P 66
SAE 52120 ht M or P 70
Steel, chrome vanadium SAE 6130 ht T 59
SAE 6195 ht U 75
Steel, silico-manganese SAE 9250 ht V 59
9 × 30 ht V 63
Steel, tungsten C-47 quench 1065°,
draw 205°C
64
Zinc   crystalline 8 - 10

Notes. Keep in mind that the scleroscope was not a very good way of measuring hardness. The inclusion of an alloy doesn't indicate that it was the only composition given that name (e.g., "gun metal", "manganese bronze"). "ht" = heat treatment. The letters designate Motor Transport Corps Modified S.A.E. Heat Treatments for Steels. (See S.A.E. Handbook) See SAE steel specification numbers for an explanation of them.

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