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The test was developed by Frederick Knoop [2] and colleagues at the National Bureau of Standards (now NIST) of the United States in 1939, and is defined by the ASTM E384 standard. The advantages of the test are that only a very small sample of material is required, and that it is valid for a wide range of test forces.
When doing the hardness tests, the minimum distance between indentations and the distance from the indentation to the edge of the specimen must be taken into account to avoid interaction between the work-hardened regions and effects of the edge. These minimum distances are different for ISO 6507-1 and ASTM E384 standards.
ASTM Specification E384, for example, states that the load range for microhardness testing is 1 to 1000 gf. For loads of 1 kgf and below, the Vickers hardness (HV) is calculated with an equation, wherein load ( L ) is in grams force and the mean of two diagonals ( d ) is in millimeters:
The method is specified in ASTM C849, C1326 & E384. Microindentation hardness is also called microindentation hardness or simply microhardness. The hardness of very small particles and thin films of ceramics, on the order of 100 nm, can be measured by nanoindentation methods that use a Berkovich indenter.
The type of notch introduced to a specimen depends on the material and characterization employed. For standardized testing of fracture toughness by the Charpy impact method, specimen and notch dimensions are most often taken from American standard ASTM E23, or British standard BS EN ISO 148-1:2009.
The E series of preferred numbers was chosen such that when a component is manufactured it will end up in a range of roughly equally spaced values (geometric progression) on a logarithmic scale.
Abrasion resistant steel is typically used in applications requiring high wear resistance, including backhoe buckets and teeth, bulldozer blades, dump truck beds, ore and coal chutes, augers and aggregate conveyors. [6]
The SAE steel grades system is a standard alloy numbering system (SAE J1086 – Numbering Metals and Alloys) for steel grades maintained by SAE International.. In the 1930s and 1940s, the American Iron and Steel Institute (AISI) and SAE were both involved in efforts to standardize such a numbering system for steels.