Hardness
71Rockwell hardness — (RH ) a measure of the hardness of a metal introduced by Rockwell in 1922. In a Rockwell hardness test, a penetrator makes an indentation in the metal under two constant loads, a minor load (generally 10 kilograms) and then a major load. The… …
72Knoop hardness — ▪ mineralogy a measure of the hardness of a material, calculated by measuring the indentation produced by a diamond tip that is pressed onto the surface of a sample. The test was devised in 1939 by F. Knoop and colleagues at the National… …
73Brinell hardness — (HB or BHN) a measure of the hardness of a metal introduced by J. A. Brinell in 1900. In the Brinell test (generally used for metals of uniform hardness), a hard object such as a steel ball is pressed into the material being tested. The… …
74Vickers hardness — ▪ mineralogy a measure of the hardness of a material, calculated from the size of an impression produced under load by a pyramid shaped diamond indenter. Devised in the 1920s by engineers at Vickers, Ltd., in the United Kingdom, the diamond …
75Vickers hardness number — (HV or VHN) or Vickers pyramid number (VPN) a measure of the hardness of a metal introduced by Vickers in 1922. In the Vickers test (suitable for surface hardened metals), a pyramidal diamond is pressed into the material being tested. The… …
76temporary hardness — noun : the portion of the total hardness of water that is removable by boiling whereby the soluble bicarbonates of calcium and magnesium are converted into the corresponding insoluble carbonates and are precipitated distinguished from permanent… …
77degrees of water hardness — dGH (water hardness expressed in degrees of hardness. 0 4 is very soft, 5 8 soft, up to 30 which is extremely hard water). Note that different countries use different measures: 1 English (Clark) degree is 14.3 p.p.m. calcium carbonate, 1 American …
78water hardness — the concentration of calcium and magnesium ions in water expressed as p.p.m. or mg/l of calcium carbonate equivalents. Water hardness expressed in degrees of hardness. 0 4 is very soft, 5 8 soft, up to 30 which is extremely hard water. Note that… …
79Brinell hardness — Bri·nell hardness brə .nel n the hardness of a metal or alloy measured by hydraulically pressing a hard ball under a standard load into the specimen Brinell Johan August (1849 1925) Swedish engineer. After studying the internal composition of… …
80Brinell hardness number — n a number expressing Brinell hardness and denoting the load applied in testing in kilograms divided by the spherical area of indentation produced in the specimen in square millimeters * * * Bri·nell hardness number (brĭ nelґ) [Johann August …
