How Rockwell Hardness Testing Supports Modern Material Evaluations

Many new products entering the market today are based on new materials and are manufactured using novel processes. These new materials are playing increasingly important roles—supporting innovation and boosting competitiveness in technology-driven industries. Identifying the potential for material failure has never been more essential and modern testing capabilities deliver the insights quality managers need to assess material performance.

Exposure to loads, pressures and extreme temperatures in manufacturing has the potential to affect the performance of parts comprised of metals and metal alloys. Due to complex sample geometry and linear correlation between hardness and tensile strength in metals, hardness testing is often the best way of establishing that components will survive and perform in their intended applications. Hardness testing is also applicable to evaluations of ceramic and plastic materials. The relative simplicity of hardness tests, in combination with the ease in which results may be obtained and reviewed, makes them an essential component of the quality control process.

Hardness is the mechanical resistance of a material to the indentation of another harder specimen. Hardness testing is typically undertaken to assess resistance to plastic deformation, a value of tremendous importance to the determination of part quality in a wide range of industries and applications.

Rockwell hardness testing is a method of determining the relative hardness of a material. In a Rockwell hardness test, hardness is measured by determining the depth of residual penetration by a steel ball or a diamond point under load. Rockwell testing is the most commonly conducted hardness testing, as the testing procedure is simple and the readings can be directly attained from the testing machine.

Accurately determining the hardness of a material for any given application involves several factors including the type of material, specimen geometry, surface conditions, exposure to heat treatment processes and production requirements.

A range of different hardness tests may be applied to determine different hardness values for the same test specimen. Selection of the type of hardness test is often influenced by end-customer requirements, as hardness measurements are commonly reported values on spec sheets accompanying the delivery of manufactured goods.