Metals are naturally occurring elements that exist in solid form. These materials have high economic value and unique properties, making them ideal for widespread engineering applications. Some of the most popular metals on earth include iron, copper, aluminum, platinum, gold, tungsten, cobalt, lead, beryllium, molybdenum, and titanium. When combined, these metals form distinct classes of alloys with superior properties.
Before beginning the metal fabrication process, it’s necessary to understand the composition of the metal you’ve selected. It’s the first step in ensuring a successful outcome in your project. Metal testing has existed since the late 1900s, and with each passing decade, new types and methods of metal tests have emerged. Today, advancements in material informatics, rapid manufacturing, and green practices have improved the metal testing process.
If you want to fabricate metals in 2024, you should read to the end. We’ll cover the following subtopics:
- What is Metal Testing?
- Classes of Metals According to Their Properties
- Types of Tests to Conduct for Optimal Results in Metal Fabrication
- 5 Fundamental Benefits of Conducting Metal Tests
- 3 Common Issues in Metal Testing
What is Metal Testing?
Metallurgical testing, also known as metal testing, involves conducting scientific experiments and inspections on metals and their alloys to compare their composition against a given set of parameters, using industry-approved methods, machines, and skills, to ascertain their usefulness in various engineering applications. Metal testing uncovers the metal’s physical, mechanical, or chemical properties before, during, and after manufacturing.
Metal materials are examined in laboratories to comply with industry standards and client requirements. Metal tests can be destructive and non-destructive. Destructive metal tests involve pulling the particles apart to assess their behavior under certain conditions. In this method, the metals are damaged and disposed of. However, non-destructive tests do not cause physical damage to the metal material.
Classes of Metals According to Their Properties
Every intending metal manufacturer must understand the properties of metals if they hope to maximize their potential through innovative applications. We’ve grouped metals according to their characteristics: physical, mechanical, and chemical properties.
Physical Properties
Tests to ascertain the physical properties of metals describe the characteristics of metals that are visual and measurable. You can examine the physical features of metals with your sensory organs without modifying their composition. Physical properties of metals include color, coefficient of linear expansion, heat conductivity, density, electrical conductivity, luster, sonority, and solubility.
Mechanical Properties
The mechanical properties of metals refer to how the metals perform when you apply external forces and loads to them. This information determines the usefulness of a product and its service lifespan. Some of the mechanical properties of metals include tensile strength, strain, stiffness, brittleness, malleability, ductility, fracture toughness, elongation, and contraction.
Chemical Properties
You don’t have to conduct chemical tests on all metals or alloys. However, it’s valuable in identifying the composition of aluminum, nickel alloys, carbon steel, zinc alloys, cast iron, copper alloys, cobalt alloys, and magnesium. A fundamental chemical property of metal is its reactive properties. Metals react with oxygen and hydrogen to form oxides. Metals also easily corrode and lose their electrons. They’re good reducing agents and have high electropositivity.
Types of Tests to Conduct for Optimal Results in Metal Fabrication
To achieve parts with high precision, quality, durability, and performance, you should start by compiling and reviewing results from multiple test groups. Some of the general tests to conduct before committing to a manufacturing project include
- Melting and Boiling Point Test: A melting point determines the temperature at which the metal moves from a solid to a liquid state under heat. The boiling point of a metal determines the temperature at which the metal compounds change from liquid to a gaseous state. These tests help manufacturers ascertain the purity level of metal compounds. The best method for measuring this is the capillary method.
- Density Test: A density test measures the volume of a metal to its mass. It determines whether a metal is heavyweight or lightweight. You calculate the result by dividing the Mass by the Volume. Density tests reveal details about the composition of a metal, primarily to know if it contains impurities that could reduce its machinability. You can identify the density of metal using a hydrometer or a densitometer. Based on the Archimedes principle, you can determine the thickness of metals using the buoyancy or displacement methods.
- Acoustic Emission Test: An acoustic emission test uses sensors to monitor the ultrasonic stress waves that emit from the metal when it deforms under stress to detect and expose cracks, yielding, creep, and corrosion on the metal material.
- Conductivity Test: An electrical conductivity test allows you to determine how well metals allow electricity to pass through them. You perform conductivity tests using several methods, including the electric bridge and the electromagnetic induction (eddy current) method. You can use an ohmmeter to measure electrical resistance and an amperometric meter to measure currents of the constant reducing voltage applied between two electrodes. Thermal conductivity test measures the ability of metals to transmit heat. You can conduct this test using two techniques: steady-state and transient methods.
- Hardness Test: This non-destructive test involves determining the metal material’s ability to resist penetration, indentation, or scratches when impacted by external loads. You ascertain the hardness of metals using methods such as the Brinell, Vickers, Knoop, Rockwell, Shore, and Mohs scale of hardness tests. Metals with high surface wear and abrasive resistance are considered hard metals.
- Ductility Test: This test can also be called the bend test. Ductility tests ascertain the point where the metal undergoes deformation (stretches or bends) before fracturing when exposed to pressure. You measure the ductility of metals by the percentage of elongation and the percentage of reduction.
- Tensile Test: It’s a failure analysis test used to measure a metal’s tensile strength, ductility, and yield under stress. It measures the ability of metals to elongate and break under an applied pulling force.
- Impact Test: This test measures the ability of a metal to resist fracturing (deformation) by calculating the energy absorbed when you apply an external load to it. The standard methods for conducting impact tests are the Charpy test, Izod test, and drop weight test. A pendulum impact testing machine is used to determine the strength and toughness of the material, according to ASTM International standards.
- Compression Test: The compression test measures the ability of metallic materials to resist stress under compressive loads or at room temperature. Under the ASTM International standard, the compression test determines the yield point, the stress-strain curve, the compression strength, and Young’s modulus.
- Fracture Toughness Test: The fracture toughness test measures the ability of a cracked metallic material to resist further cracking when you apply a tensile load to it. Standard tests used to measure fracture toughness are Crack displacement, Izod, and Charpy tests.
- Flame Test: The flame test measures the presence of some metallic ions in an unknown metal compound by heating the material. The metal is then identified based on the color of the flame.
- Microstructure Test: You can perform this test using an optical microscope or image scanning devices to magnify the amount and size of the hidden features of metals under examination. The standard process involves selecting the test sample, sectioning it, mounting the test sample in a plastic or epoxy material before placing it in a heated mold, grinding, polishing, and etching the mold to reveal features such as the grain boundaries, fraction, corrosion, and decarburization.
- Corrosion Test: This test measures the ability of a metal material to resist corrosion in a desired environment. It ascertains the severity or type of deterioration that happens when you place a metal under specific conditions. Some methods of testing the corrosion of metals include the salt spray test, corrosion coupon test, electrochemical test, crevice corrosion test, weathering test, and copper strip corrosion test.
- Radiation Resistance Test: A radiation test helps you measure the ability of metals to resist radiation when exposed to a radiation source (cosmic and terrestrial) within a given period.
5 Fundamental Benefits of Conducting Metal Tests
There are over 90 types of metals in the periodic table. When combined to form alloys, the number goes up much higher. As such, selecting a suitable metal for complex applications can be tricky. These tests help simplify the process.
Below are some of the principal reasons you should invest in metal testing at the core stages of the manufacturing cycle.
Metal Testing Helps You Minimize Defects in Production
Metal testing helps you to protect the integrity of your final parts, minimize waste, and reduce the overall cost of production. By identifying the raw materials showing signs of crack, discoloration, shrinkage holes, and surface decarburization, you’re minimizing the potential product damage that could occur during the manufacturing process. Manufacturers can take further steps to correct these defects or eliminate the material from further processing. Tackling defects on raw materials is less capital intensive than after it undergoes final processing.
Metal Testing Helps You Maximize the Full Potential of a Material
Learning about the composition of metals helps you maximize their potential. We’ve established that metals possess unique characteristics. These unique properties may, in some cases, make them sensitive to new environments and elements. Knowing how your ideal metal will react to certain conditions makes it easier to plan for its use. Metal testing helps you identify which metals have poor resistance to corrosion and combustion, and longer life cycles, and can facilitate innovations in critical industries.
Metal testing Increases Production Efficiency
Testing materials before introducing them to the machine, helps you optimize the efficiency of the manufacturing process. Corrupted metals can damage or reduce the machine’s speed because of the strain they cause. You also don’t don’t want to lengthen the manufacturing time because of sporadic stoppages to troubleshoot potential errors. Every metal fabricator wants to hasten their client’s time to market. One of the ways to accomplish that is to assess the suitability of every material that goes into the production cycle.
Metal Testing Helps You Identify Health Risks
Not every metal should be part of the manufacturing process. Certain metals contain toxic elements that pose severe threats to life on Earth. Irregulated exposure to heavy metallic compounds like lead, arsenic, mercury, chromium, and cadmium can cause severe organ failures and other health problems. While some of these metals have not received federal bans, consumer agencies within and outside the United States have kicked against their use in commercial products.
Metal Testing Helps You Protect Your Investment
You should test metal materials before using them to spare yourself and your business from industry sanctions and legal suits in the future. Testing your materials to ensure they’re in good condition before committing to a project and educating your consumers on the material composition of each final product allows you to gain their trust. Trust breeds loyalty. You need consumer loyalty to expand your market share and dominate your industry. Testing your metals also protects your funds from unscrupulous sellers who intentionally impair the quality of their metals for selfish reasons.
3 Common Issues in Metal Material Testing
- Metal testing can be expensive, especially when it’s destructive. In destructive metal testing, you no longer recover the materials once used in the testing process as they become damaged. Also, metal detection machines can be expensive if needed for complex testing. As an industrial manufacturer, you’ll need to run multiple tests on the material to detect its hidden properties. You’ll also need experience to convert the test data into valuable insights. As such, you may spend thousands of dollars to achieve the best results.
- Inadequate test samples might make the testing process complicated. Substantial amounts of metals are needed as samples from the batch of raw materials to conduct failure analysis and condition assessment tests before proceeding with the project. If the test sample is insufficient, your results may become inconclusive or misleading. Poor results can cause further production issues, leading to further material waste.
- Carelessness and incompetence of metal testers can also lead to inconclusive and inaccurate test results. While you perform most tests on machines and testing instruments, you need humans to troubleshoot the machines and pass judgment on the final results, to aid decision-making. Negligent or inexperienced operators can jeopardize the entire process, incurring huge losses for all those involved.
Final Thoughts
Understanding the composition and suitability of metals for different industrial applications maximizes your chance of achieving commercial success with your final products. To effectively generate practical insights from metal material tests, you should partner with a metal technology firm.
Metal technology firms have the proper expertise, technology, and experience to conduct strict quality inspections on your choice of metals. They understand the industrial guidelines and can proffer bespoke solutions. At PTI Tech, we collaborate with our vendors and in-house engineers to provide you with a holistic metal fabrication service.
We understand the importance of conducting metal material testing and market research on your product before allowing you to commit to the manufacturing process. Our capabilities include market research, product development, rapid prototyping, casting, additive manufacturing, injection molding, and quality control for commodity and specialty metals. Get in touch with us today to make your innovation a reality.