Hardness Testing

TMT’s Macrohardness testing capabilities

Brinell Scale (HBW)

The Brinell scale is meant to test the hardness of metal alloys and similar metals. A small, hand-operated device presses a steel ball (with known dimensions) into the test specimen. At its most basic, the Brinell hardness number (HB) is then determined by examining the surface area of the indentation, compared to the dimensions of the steel ball that made the indentation. 

Rockwell Scale 

The Rockwell scale is also a hardness scale based on indentation. However, unlike the Brinell test, the Rockwell hardness test measures and compares two different indentations–one from a preload or minor load, and one from a larger load, also called the major load–in order to test the hardness of a specimen.

The Rockwell hardness has several different alternative scales, based on the metals being tested, as well as a few other factors. 

• Rockwell A (HRA) tests cemented carbides, and thin types of steels
• Rockwell B (HRB) is more commonly used, and tests copper and aluminum alloys, and more malleable types of iron
• Rockwell C (HRC) is also a commonly used scale, often used to test the hardness of normal steel, hard-cast irons, titanium, and other materials whose hardness exceeds HRB

There is also another type of Rockwell scale called the superficial Rockwell hardness scale, which tests the hardness of very thin and/or brittle materials. We operate with HR15N and HR30N scales when a superficial Rockwell test is recommended.

Leeb Hardness Testing

Also called the Leeb Rebound Hardness Test (HL or LRHT) is another common way to test the hardness of metal. This non-destructive test is used for large workpieces that weigh over 1 kg, which would be more difficult to test otherwise. This is also a portable test that doesn’t require a dedicated testing area or lab to complete.

TMT’s Microhardness testing capabilities

Knoop (HK)

The Knoop hardness scale is often used for small parts or thin sections of materials, where only a thin indentation can be made on the metal. This test is advantageous when only small samples of material are available for testing, and it’s also valid for use with a wide range of test forces, making it a more flexible microhardness test. 

Vickers (HV)

This flexible hardness test can work with all metals, and has much simpler calculations than other hardness tests. It also measures indentations onto the test material to measure the material’s hardness, but at a microscopic level compared to macrohardness tests.