The Vickers hardness test is a widely used standard test method for measuring the hardness of metals. It measures the ability of a material to withstand penetration by an indenter when it is pressed with a fixed load. You can also use it to measure the indentation hardness of non-metallic materials, provided they are sufficiently dense. The method was invented by British engineers George Sandland and Robert L. Smith in 1921. This article explains the Vickers hardness test, its principle, and how it can be applied in various industries.
I. What is the Principle of Vickers Hardness Testing?
The Vickers hardness testing basic principle is to observe the ability of a material to resist permanent deformation from a specified load. All materials have a certain level of elasticity.
The Vickers hardness test measures the maximum load applied to an object without its deformation exceeding a specified value. To measure the hardness, a diamond indenter is pressed against a test sample, and a specified load is applied. The indent’s measurement is then used to calculate the value of Vickers hardness which is translated and converted using the Vickers hardness scale chart. You can use this method to test the hardness of almost all materials, and its scale is one of the widest among all other hardness tests.
II. What are the Applications of Vickers Hardness Testing?
The Vickers hardness test is an industry-standard method for measuring the hardness of metals, plastic, and ceramics. It can be applied to various metals, including high-alloyed steels, cast iron, low-alloy steels, nickel-plated steel wire, and brass.
This method makes a very small indentation on the test piece, making it suitable for measuring materials with very thin sections, such as aluminum foils, or with very small parts such as pipe tubing.
The Vickers hardness test method is used extensively in the manufacturing industry to measure the material quality before or after mechanical processing or forming operations.
Related Article: What are the Advantages and Disadvantages of the Vickers Method?
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III. Applications of Vickers Method Depending on the Load Range
Range 1 HV – 300
Diamond Pyramid 136°
Structural Constituents, very thin layers
Diamond pyramid 136°
Thin layers CHD/SHD/NHD series, thin sheet metal, small specimens
Diamond pyramid 136°
IV. Factors for the Selection of the Correct Test Force and Test Method
Surface finish is an important factor in selecting the correct test force and method. The surface should have a smooth, spherical surface finish for precision-machined parts. This is because the Vickers hardness test makes a small indent which would cause inaccurate results to be recorded if the test sample surface is rough.
The Vickers hardness test method is based on the least area by which the indentation is required to be made. The specimen’s size determines the deflection it can withstand from a given load before it can no longer support the load. You should observe the defined sample sizes in the Vickers test standards to ensure you choose the material of the right size.
The thickness of a specimen has a predefined maximum value. The specimen should be at least one and half times the thickness of the indenter diagonals. The Vickers test standards define the sample thickness as between 0.085 and 6.5 mm.
The Vickers hardness test is a very reliable method for measuring the physical properties of materials. It is a very popular method in engineering, industrial use, and the oil and gas industries. The Vickers hardness test allows engineers to inspect materials before they undergo production or post-production processes such as heat treatment, forming, or welding.