It’s a never-ending battle.
Engineers and metallurgists are always finding different ways to protect metals from corrosion, especially for metal pipes and tubes that must be in contact with the soil. Alloys like bronze have proved to be an effective anti-corrosion material. It is also widely accepted as an alternative to corrosion-prone metals in other critical operations. However, the strength and durability of this alloy are still a crucial consideration for many jobs and processes that put it in direct contact with external loads and forces. But how do you determine the hardness of this alloy? We’ll tell you how in this post. Let’s get started.
I. What is the Hardness of Bronze?
Bronze is an alloy of copper, and it is the result of adding one of the elements that include aluminum, tin, beryllium, and nickel to copper to get bronze. The hardness of bronze often depends on the quantity of these other elements added to copper to get bronze. And the measure of this quantity is often related to the measurement of bronze’s hardness. Hence, the hardness of bronze can be defined as measuring its ability to resist deformation due to external forces based on the quantities of elements added to copper that make the resulting bronze hard.
II. Is Bronze a Hard Metal?
Bronze is an anti-corrosive metal which makes it suitable for specific components that will be subjected to moisture during use. However, it is considered a dual utility material since it is both anti-corrosive and hard. Its hardness makes it suitable for a component that can withstand external forces likely to cause deformation for other components made from a different material. Bronze can give a tensile strength of up to 1,400MPa depending on the additional element that has been added to copper to form a particular bronze. However, the quantity of this additional element is equally a determining factor for its hardness and tensile strength.
III. Which is Harder, Bronze or Brass?
While bronze combines copper and various other elements, brass is simply a combination of copper and zinc. This different combination of constituents gives both brass and bronze their distinct character, which includes their weight, melting point, anti-corrosion, and hardness. Using standard hardness testing methods like the Brinell test to confirm the hardness of both metals shows that brass hardness ranges from 55 to 73 while bronze hardness ranges from 40 to 420. The preceding shows that bronze can withstand more external force than brass and therefore is the harder of the two. The combination of copper and beryllium gives the hardest form of bronze.
IV. How do you Test for Hardness?
Testing for a material’s hardness is often required for design specification and choosing a suitable material for manufacturing specific components and parts. The most common types of hardness test methods include the Rockwell, Brinell, and Vickers hardness testing methods. These methods have various peculiarities that make them suitable for different materials. Furthermore, particular emphasis is given to specific factors when selecting the best hardness test methods. These factors include the material’s size, quantity, type, and estimated hardness. Also, the accuracy and the compliance required for the test are essential considerations.
V. Hardness Test Methods for Bronze Hardness Testing
Here are the most popular methods of bronze hardness testing
- Rockwell Test – This test requires using a Rockwell hardness testing machine that includes an indenter ball made from a tungsten carbide of 4 different sizes or a diamond cone. The indenter ball uses a set of known loads to cause a depression on the surface of the bronze material, with the loads often ranging from 15kgf to 150kgf. Additionally, the application of the loads comes in two sets of minor and major loads, where the minor loads apply first, followed by the major load. Calculating the Rockwell hardness value uses the depth of the depression resulting from applying the major load.
- Vickers Test – This test utilizes a more comprehensive load range and can measure indentation caused by 10gf or a 100kgf which means that it can assess the hardness of both thick and thin materials. The Vickers test employs a diamond indenter with a pyramid shape which applies a known load to cause an indentation on the bronze material with a known thickness. The width of the indention helps in calculating the material hardness. However, the Vickers hardness test uses an optical instrument like a microscope to ascertain the width of this indentation.
- Brinell Test – This test often creates a significant depression on the test material surface, which makes it unsuitable for thin materials. It usually applies to thick materials with rough surfaces and inhomogeneous structures. The indenter in this test is a carbide ball with a diameter ranging from 1 to 10mm. Also, the loads applied range from 1 to 3,000kgf, which causes the indentation that is measured using an optical instrument. The diameter of the depression caused by the indenter helps to calculate the Brinell hardness value.
Conclusion
In conclusion, bronze is a double utility material often used when anti-corrosive properties and high tensile strength are required. However, the required hardness of the bronze material you need will depend on the hardness testing method that is available to you. Still, you must consider specific parameters, including the bronze material’s size, type, and use.