What Does Macrohardness Mean?
Macrohardness is the measurement of the hardness of materials tested with high applied loads.
Macrohardness measurement of materials is a quick and simple method of obtaining mechanical property data for the bulk material from a small sample. It is also widely used for quality control of surface treatment processes.
Macrohardness is also known as macroindentation hardness testing.
Corrosionpedia Explains Macrohardness
Hardness measurement can be defined as macro-, micro- or nano-scale, according to the forces applied and displacements obtained. Macro means large, therefore macrohardness is a measurement of the hardness of a material when a large force is applied.
Macrohardness can be regular or superficial. In regular macrohardness it is applicable to large area with deep penetration, whereas in superficial macrohardness it is applicable to large area with shallow penetration.
Macrohardness tests can be applied with heavier loads than microindentation tests. It has been found that the microhardness of almost any material is higher than its macrohardness.
Macrohardness can be measured with three methods:
- The Rockwell hardness test is based on the net increase in depth of impression as a load is applied. It is a useful measure of relative resistance to indentation of various grades of plastics.
- The Brinell hardness number is obtained by dividing the load used, in kilograms, by the actual surface area of the indentation, in square millimeters. The result is a pressure measurement, but the units are rarely stated.
- Vickers hardness is a measure of the hardness of a material, calculated from the size of an impression produced under load by a pyramid-shaped diamond indenter. It is reliable for measuring the hardness of metals, and is also used on ceramic materials. In this test the force used is much lighter than the force used in the Rockwell hardness test.
Macrohardness tests are the most widely used methods for rapid routine hardness measurements. It is the type of hardness testing used for normal-sized materials with standard loads, indenters, and dwell times. The indenting forces in macrohardness tests are in the range of 50N to 30000N.