How to test the hardness of steel plates

The hardness testing of steel plates can usually be carried out through the following methods:

Brinell Hardness Test:

During testing, a hardness tungsten ball (or tungsten carbide alloy ball) with a certain pressure is pressed into the steel surface, and then the diameter of the indentation is measured.

The measurement of indentation diameter is usually carried out using an optical reading microscope in two mutually perpendicular directions of the indentation. After obtaining the average diameter of the indentation, the Brinell hardness is calculated by substituting it into the formula.

In recent years, there has also been a method of calculating Brinell hardness by measuring the depth of the indenter pressing into the tested material and converting it into area.

Rockwell Hardness Test:

During testing, different shapes of steel needles or ball heads (diamond cones or steel balls) are used to press into the steel surface under a certain load, and the depth of pressing is measured.

By reading the scale on the indicator, the Rockwell hardness value can be determined.

The Rockwell hardness test uses different indenters and test forces, resulting in different combinations corresponding to different scales of Rockwell hardness. There are three commonly used rulers: HRA, HRB, and HRC. Depending on the hardness of the experimental material, rulers with different hardness ranges are selected.

Vickers Hardness Test:

During testing, a diamond pyramid shaped indenter is used to apply a load on the steel surface, and then the diagonal length of the indentation is measured.

By calculating the area of the indentation and the ratio of the load, the Vickers hardness value can be determined.

In actual measurement, there is no need for calculation, but the measured hardness value is directly obtained by looking up the table based on the measured diagonal length d.

Ultrasonic hardness test:

This is a non-destructive testing method suitable for measuring the hardness of large structures.

Shore Hardness Test:

The testing principle is to drop a specified diamond punch from a fixed height onto the surface of the sample, and the punch will bounce a certain height. The ratio of the bounce height to the drop height is used to calculate the Shore hardness.

Leeb Hardness Test:

The principle is to use a specified quality of impact body to impact the surface of the sample at a certain speed under the action of elasticity, and calculate the hardness value by the ratio of the rebound speed of the punch at a distance of 1mm from the surface of the sample to the impact speed.

Different hardness testing methods are suitable for different materials and occasions, and the choice of method depends on specific testing requirements.

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