For our purposes, measuring material properties refers to the measurement of those properties that identify the suitability of different steels for the applications we have in mind. We are primarily interested in the mechanical properties such as hardness, wear resistance, toughness, shock resistance and impact resistance that tell us if the steel we may select will stand up to the rigors of our specific application. The tests that we will employ will typically involve the application of force to a material specimen to observe the elastic or inelastic behavior of the material. It is usually necessary to indent or destroy the material sample during testing.
The most common tests for steel comparisons are for hardness, resistance, and tensile strength. There are a variety of hardness test methods, but we will only cover the Rockwell and Brinell tests which are most suited to mold base technology.
Hardness is one of the most used mechanical properties and refers to a material’s ability to resist being permanently deformed. The Rockwell and Brinell hardness test methods measure the steel’s ability to resist penetration and are measured on different scales depending on the range of the steel’s strength.
Impact testing is used to measure material toughness or its ability to withstand a sudden impact or shock. Impact strength can also be defined as the amount of energy required to fracture a given volume of material. The most common tests for impact are the Charpy and Izod tests.
Tensile tests are used to apply a stress to a material and then record the response to this stress. A material sample is stretched or pulled in a machine until it fractures. The machine records the maximum amount of pull force that the sample can withstand before breaking. These machines are capable of applying extremely high tension loads if desired.
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