Today's complex world, where chaos often reigns, requires something that can bring order. When it comes to material testing, this order is brought by international standards. These standards guarantee consistency, reliability, and accuracy in different tests and applications. The most common organizations that provide international standards for tensile testing are ASTM (American Society for Testing and Materials) and ISO (International Organization for Standardization).
Standards exist in every branch of material testing. Today, we focus on the 10 most widely used standards in tensile testing. In this blog, we will discuss these ASTM and ISO standards in detail and explain why they are so prevalent. We will look at what these standards entail, the specific instructions they provide, and their applications.
Understanding International Standards for Material Testing
The purpose of compliance with standards is to provide structured guidelines to be used in a number of testing procedures. They dictate best practices for conducting materials tests so that results are comparable and reproducible across different laboratories and industries worldwide.
International standards cover aspects such as the types of equipment to be used, specimen dimensions and preparation, testing procedures, environmental conditions, and methods for interpreting and reporting results. These guidelines are fundamental to every branch of material testing. They are expertly created by professionals who understand the needs of the industries they represent, reflecting best practices and technological advancements.
Prominent organizations such as ASTM International, ISO, DIN, and BS have an important role in developing and publishing these standards. ASTM International, founded in 1898, develops and publishes voluntary consensus standards for a broad range of materials and products. ISO, established in 1947, is an independent body that provides assurances regarding product quality, safety, and efficiency globally. DIN, the German Institute for Standardization, publishes many different types of standards in Germany and internationally. The British Standards Institution (BSI) develops standards covering many sectors and is recognized globally. These organizations collaborate with experts from numerous fields to create standards that reflect current best practices and technological advancements.
Compliance with international standards in tensile testing is important for several reasons. In the first place, they provide assurance that testing procedures are consistent across different laboratories, allowing reliable data comparisons. Standards provide guidelines for specimen preparation and testing methods, helping maintain tested materials' quality and integrity. They also make certain that materials meet safety specifications, which are particularly important when it comes to applications such as construction and aerospace.
1. ASTM E8/E8M - Tension Testing of Metallic Materials
ASTM E8/E8M is one of the most widely used standards for determining metallic materials' tensile properties. This standard describes methods for tension testing different forms of metals at room temperature. It is required for assessing yield strength, tensile strength, yield point elongation, and reduction of area.
Importance and Use: Tension tests provide valuable information on materials' strength and ductility under uniaxial tensile stresses. This data is crucial for comparing materials, aiding alloy development, maintaining quality control, and supporting design processes under certain conditions. ASTM E8/E8M is extensively used for acceptance testing of commercial shipments due to its established reliability in the trade.
Scope: ASTM E8/E8M specifies procedures for tension testing metallic materials in any form at room temperature. It addresses the determination of yield strength, yield point elongation, tensile strength, elongation, and reduction of area. The standard differentiates between gauge lengths for round specimens, with ASTM E8 requiring 4D and ASTM E8M requiring 5D. This difference in gauge length is a notable distinction between the two versions. Powder metallurgy materials are exempt from this requirement to maintain specific projected areas and densities.
Testing Methods: ASTM E8/E8M allows an array of specimen types, including bars, tubes, sheets, and round specimens. The standard outlines three primary test control methods: stress rate control, strain rate control, and crosshead displacement control, called Methods A, B, and C respectively. These methods provide precise control over test speeds and are necessary for accurate measurements of yield properties and elongation.
2. ISO 6892-1 - Tensile Testing of Metallic Materials at Ambient Temperature
ISO 6892-1 is an international standard that specifies the method for tensile testing of metallic materials at room temperature. Similar to ASTM E8/E8M, this standard guarantees consistency and reliability in determining mechanical properties such as yield strength, tensile strength, and elongation. However, it differs in its approach to certain procedural details and specific requirements for specimen preparation and testing conditions.
Importance and Use: ISO 6892-1 provides guidelines for performing tension tests for assessing the strength and ductility of metallic materials under uniaxial tensile stresses. This information is vital for developing new alloys, maintaining quality control, and supporting design processes. The standard ensures that tests conducted in laboratories produce comparable and reproducible results.
Scope: The standard describes tensile testing of metallic materials at room temperature, defined as 10°C to 38°C (50°F to 100°F). It specifies procedures for determining key properties such as yield strength, tensile strength, yield point elongation, elongation, and reduction of area. ISO 6892-1 differentiates between specimen types and preparation methods, including guidelines for thin sheets, wires, bars, and sections of varying thicknesses.
Testing Methods: ISO 6892-1 outlines control methods for test speeds, including stress rate control, strain rate control, and crosshead displacement control. These methods are crucial for accurate measurements of yield properties and elongation. The standard focuses on maintaining specified test speeds. It also requires specific extensometers to measure strain accurately. Different types are recommended based on the test requirements.
Practical Considerations: The standard highlights the importance of specific equipment and testing conditions to achieve consistent results. The testing machine's force measuring system must comply with ISO 7500-1, class 1, or better. Different gripping technologies, such as wedge grips and hydraulic grips, are used to secure specimens during testing, with a focus on maintaining consistent clamping forces. ISO 6892-1 also details the preparation and measurement requirements for different specimen types.
3. ASTM A370 - Mechanical Testing of Steel Products
ASTM A370 is a standard for the mechanical testing of steel products, including tensile testing. This standard is widely applied to assess the mechanical properties of steel, stainless steel, and related alloys. It provides a comprehensive framework for evaluating material performance.
Importance and Use: ASTM A370 is used to determine the specified mechanical properties of steel and related alloy products to verify their conformance to material specifications. The standard is extensively used by ASTM Committees and other standards bodies for conformance testing, quality control, and evaluation of materials after service exposure.
Scope: ASTM A370 covers a range of mechanical tests, including tension, bend, hardness (Brinell, Rockwell, and portable methods), and impact tests. These tests determine product specifications and properties. The standard specifies procedures to avoid testing method deviations. It includes detailed guidelines for testing different product forms, such as bar products, tubular products, fasteners, and wire products. Each annex provides specific requirements relevant to these products.
Testing Methods: For tensile testing, ASTM A370 outlines methods to determine tensile strength, yield strength, and elongation.
Practical Considerations: ASTM A370 specifies that inch-pound values are standard, with SI unit conversions provided for reference. The standard also addresses the need for appropriate safety, health, and environmental practices during testing. Additionally, it directs users to ISO/IEC 17025 for criteria for evaluating testing laboratories.
4. ASTM D638 - Tensile Testing of Plastic Materials
ASTM D638 applies to both reinforced and unreinforced plastic materials to determine their tensile properties. The purpose of this standard is to assess the mechanical strength of plastics, which is extremely important for quality control in the plastics industry.
Importance and Use: ASTM D638 provides standardized methods to produce tensile property data, which are used for controlling and specifying plastic materials. This data is also valuable for qualitative characterization and research and development. Tensile properties, such as tensile strength, yield strength, and elongation, can vary with specimen preparation, testing speed, and environmental conditions. Therefore, precise comparative results require careful control of these factors.
Scope: This standard specifies tensile testing of unreinforced and reinforced plastics using standard dumbbell-shaped specimens. Testing conditions include pretreatment, temperature, humidity, and testing machine speed. ASTM D638 applies to materials up to 14 mm thick. For thinner materials, such as 1 mm thick film, ASTM D882 is preferred. The standard also includes the option to determine Poisson's ratio at room temperature. It is important to note that while ASTM D638 and ISO 527-1 address similar subject matter, they differ in technical content.
Testing Methods: ASTM D638 involves applying a tensile force to a sample specimen using a universal testing machine at tensile rates ranging from 1 to 500 mm/min until the specimen fails (yields or breaks). Key properties measured include tensile strength, tensile modulus, and elongation. Tensile strength is the amount of force applied to a plastic before it yields or breaks. Tensile modulus measures material stiffness, and elongation indicates ductility. The test also measures Poisson's ratio, which describes the connection between the longitudinal and lateral strains of the material.
5. ASTM E21 - Tensile Testing of Metallic Materials at Elevated Temperatures
ASTM E21, the fifth standard on our list, focuses on the tensile testing of metallic materials at elevated temperatures. The purpose of this standard is to determine how metals behave under high-temperature conditions, which is fundamental knowledge in industries where materials often operate under thermal stress.
Importance and Use: ASTM E21 estimates how metals can withstand tensile forces at high temperatures. This test method helps predict material behavior under various stress conditions such as compression and shear, using established relationships between different stress states. Additionally, the test gives insights into a material's ductility, indicating its ability to deform without cracking.
Scope: The standard outlines procedures and equipment necessary for determining tensile strength, yield strength, elongation, and reduction of area for metallic materials tested at elevated temperatures. ASTM E21 specifies that these tests should be conducted above room temperature, starting at temperatures higher than 38°C (100°F). The standard provides precise guidelines for temperature measurement, requiring thermocouples to be calibrated annually.
Testing Methods: According to ASTM E21, it is important to align machines accurately and apply loads precisely to specimens in order to minimize bending strains. Testing machines must meet strict requirements so that the maximum bending strain does not exceed 10% of the axial strain. The standard also details the preparation of different specimen shapes, such as round and flat specimens. It specifies the strain rates to be maintained during testing to determine yield and offset yield values. The standard also suggests maintaining specific strain rates throughout the entire test to record a complete stress-strain curve.
Practical Considerations: Temperature control is a key aspect of ASTM E21. The standard requires thermocouples for precise temperature measurement, with allowable deviations specified based on the temperature range. For example, temperatures up to 980°C must be measured within ±3°C. Extensometers, compliant with ASTM E83 Class B-2 standards, are necessary to measure strain accurately.
6. ISO 527 - Tensile Testing of Plastic Materials
ISO 527 is the sixth standard on our list, specifically designed for determining plastic tensile properties. The purpose of this standard is to provide assurance that tensile strength and elongation measurements are accurate and that the measurements can be used for quality control and research purposes.
Importance and Use: ISO 527 provides comprehensive guidelines for testing the tensile properties of both filled and unfilled plastic materials. The standard focuses on the reproducibility of test results between different laboratories and across international borders.
Scope: ISO 527 covers the determination of the tensile properties of plastics using standard dumbbell-shaped specimens. Test conditions include specimen preparation, testing speeds, and environmental conditions. The standard is applicable to plastics of various thicknesses, guaranteeing that tests on thin films, sheets, and reinforced composites are conducted correctly. ISO 527 is divided into parts that address general principles (ISO 527-1) and specific test conditions for different types of plastics (ISO 527-2).
Testing Methods: The tensile test under ISO 527 involves stretching a plastic specimen at a constant speed until it breaks. Measured properties, as in the standards we discussed earlier, include tensile stress, tensile strain, tensile modulus, yield point, and Poisson's ratio. The standard specifies precise requirements for specimen dimensions, measurement device accuracy, and testing speeds. For example, the tensile modulus is determined from the slope of the initial linear portion of the stress-strain curve, requiring high measurement accuracy. The tests can be conducted using universal testing machines equipped with appropriate grips and extensometers.
Practical Considerations: ISO 527 mandates stringent conditions for specimen preparation and testing. Specimens must be prepared according to defined dimensions, and testing must be conducted under controlled temperature and humidity conditions. The standard also outlines the need for regular calibration of testing equipment to maintain accuracy. Environmental factors, such as the effect of aging and weathering on plastics, are also considered, with tests conducted to assess changes in mechanical properties over time.
7. ASTM D3039 - Tensile Testing of Polymer Matrix Composites
Next, we have ASTM D3039, which is a standard for testing the tensile properties of polymer matrix composites, particularly those reinforced with high-modulus fibers. This standard is required in industries where composites' high strength-to-weight ratio is highly valued.
Importance and Use: ASTM D3039 generates tensile property data for material specifications, research and development, quality assurance, and structural design and analysis. It measures properties such as ultimate tensile strength, ultimate tensile strain, tensile chord modulus of elasticity, Poisson's ratio, and transition strain. These properties help engineers and scientists understand composite mechanical behavior under tensile stress.
Scope: This test method determines the in-plane tensile properties of polymer matrix composites reinforced by continuous or discontinuous high-modulus fibers. The standard applies to laminates that are balanced and symmetrical in the test direction. It includes detailed instructions for specimen preparation, including rectangular specimens with constant cross-sections. The minimum specimen length is equal to the total gripping length plus twice the width plus the gauge length. However, longer specimens are recommended to minimize bending stresses.
Testing Methods: Tensile testing according to ASTM D3039 involves applying uniaxial force to a composite specimen until it fractures. The test is conducted using a universal testing machine, which can be a tabletop or floor model, depending on the required force. For instance, testing carbon fiber composites may require a 100 or 250 kN system. The grips used must apply even pressure to prevent slipping and provide correct measurements. Specimens are typically tabbed to protect the material from damage during gripping.
Strain measurement can be done using extensometers or strain gauges. Extensometers are clipped onto the specimen to measure axial strain directly, while biaxial devices can measure both axial and transverse strains to determine Poisson's ratio. Testing is often performed in a controlled temperature chamber to simulate different environmental conditions, from cryogenic to high temperatures.
Practical Considerations: The specimen's cross-sectional area must be measured precisely before testing. Tabbing, though not mandatory, is recommended for unidirectional materials to ensure uniform stress distribution. Testing speed and environmental conditions, such as temperature and humidity, must remain consistent throughout.
8. ISO 37 - Tensile Testing of Rubber Materials
ISO 37 is notably different from other standards on our list. This is because it focuses specifically on determining the tensile properties of rubber materials, including vulcanized and thermoplastic rubbers.
Importance and Use: ISO 37, like many other tensile testing standards, is designed to produce tensile property data that are useful for quality control, material specification, and research and development of rubber products. This standard helps manufacturers and researchers understand how rubber materials behave under tensile stress. The properties measured include tensile strength, elongation at break, stress at a given elongation, and strain at yield.
Scope: The standard describes rubber materials tensile testing using two primary specimen shapes: dumbbell and ring specimens. These specimens are subjected to tensile forces in a controlled environment to measure their mechanical properties. Test conditions include specimen preparation, environmental conditions, and testing speeds.
Testing Methods: Tensile testing according to ISO 37 involves stretching a rubber specimen at a constant speed until it breaks. Key properties measured include tensile strength, which indicates the maximum stress the material can withstand; elongation at break, which shows how much the material can stretch before failing; and stress at a given elongation, which helps assess the material's response to specific stress levels. It is important to note that the testing machine must comply with ISO 5893 requirements.
Practical Considerations: Specimen dimensions must meet the standard's specifications, and the testing machine must maintain consistent clamping pressure throughout the test. Additionally, tests are often performed under controlled temperature conditions to simulate real-world operating environments.
9. ASTM F606 - Mechanical Testing of Fasteners
ASTM F606 describes the methods for mechanical testing of fasteners, including externally and internally threaded fasteners, washers, direct tension indicators, and rivets. Fasteners used in construction, automotive, and aerospace applications are subject to this standard. Central to these mechanical tests are tensile tests.
Importance and Use: ASTM F606 establishes standardized procedures for determining fasteners' mechanical properties. This includes assessing properties such as product hardness, proof load, yield strength, and axial tension. These properties are vital for making sure that fasteners can withstand mechanical stresses in many different applications.
Scope: The standard specifies procedures for tensile testing of externally and internally threaded fasteners, washers, direct tension indicators, and rivets. For externally threaded fasteners, it includes tests for tensile strength, yield strength, and proof load. For internally threaded fasteners, it covers tensile strength and proof load tests.
10. ISO 6892-2 - Tensile Testing of Metallic Materials at Elevated Temperatures
ISO 6892-2 is the last item on our list of the top 10 most widely used tensile testing standards. While we have previously discussed ISO 6892-1, which focuses on tensile testing at room temperature, ISO 6892-2 is dedicated to the tensile testing of metallic materials at elevated temperatures. This standard is similar to ASTM E21 but has distinct methodologies and specifications adapted to high-temperature environments.
Importance and Use: ISO 6892-2 is required for evaluating metal mechanical properties when subjected to high temperatures. This standard helps determine tensile strength, yield strength, elongation, and reduction of area for metals, providing data for materials used in high-temperature applications.
Scope: The standard specifies methods for tensile testing metallic materials at temperatures higher than room temperature. It includes guidelines for specimen preparation, temperature control, and testing procedures. ISO 6892-2 covers two primary testing methods: Method A, which controls the strain rate to minimize variability and uncertainty, and Method B, which allows for comparison between room temperature and elevated temperature results by using consistent strain rates.
Looking for Equipment That Will Meet Your Needs?
You will not achieve the full potential of tensile testing or sample preparation without advanced equipment that meets the necessary standards. At TensileMill CNC, we are dedicated to tensile testing, tensile sample preparation, and all related services. If you are searching for reliable equipment that handles all your testing needs, these products might interest you:
TensileMill CNC MINI for Flat Tensile Test Sample Preparation
The TensileMill CNC MINI is a compact yet powerful solution for flat tensile test sample preparation. Compliant with standards like ASTM E8 and ASTM A370, this machine offers exceptional flexibility and precision in specimen preparation. Despite its small size, the MINI features a larger table size, higher power, and greater precision and repeatability. Key features include:
- Small Footprint: Ideal for labs with limited space.
- User-Friendly Interface: Suitable for operators without extensive CNC training.
- Turnkey Solution: Ready to use with minimal setup.
- Accurate and Repeatable Results: Each test is conducted consistently.
- Free Proof of Concept: Demonstrates the machine's capabilities before purchase.
Equipped with a 10" LCD screen and our Carbon software, the TensileMill CNC MINI allows operators to quickly enter desired specimen sizes based on ASTM, ISO, DIN, JIS, or other standards. The 2.2kW (3hp) Water Cooling Spindle and designated tooling can handle an array of materials, making it easier than ever to prepare high-quality tensile specimens.
Servo-Hydraulic Universal Testing System for Tensile Testing Procedures
The SHM Class A Series of Servo Hydraulic Universal Testing Systems, available in 600kN and 1000kN capacities, is designed for high-force mechanical testing of various materials. It complies with international standards such as ASTM E8, ISO 6892, and BS 4449, which guarantees accuracy and reliability in tensile, compression, shearing, and bending tests.
- Load Frame Structure: Features a robust 4-column and 2-lead screw design for durability.
- Hydraulic Operated Tensile Grip: Simplifies operation.
- Versatile Testing Spaces: Separate spaces for tensile and compression tests.
- High Accuracy: The load cell directly measures the testing force.
- Easy Maintenance: A chain-type transmission and a non-aging oil cylinder clearance seal.
- Secure Grip: A half-open tensile jaw seat prevents deformation and slippage during tests.
This system is ideal for industries requiring precise and reliable high-force testing, thereby verifying that your materials comply with the highest performance and safety standards.
Bringing It All Together: Top Tensile Testing Standards
There are numerous standards relevant to tensile testing, but the ten most widely used globally are established by ASTM and ISO. These standards are ASTM E8/E8M, ISO 6892-1, ASTM A370, ASTM D638, ASTM E21, ISO 527, ASTM D3039, ISO 37, ASTM F606, and ISO 6892-2.
Each standard has unique features: ASTM E8/E8M and ISO 6892-1 focus on metallic materials at ambient temperatures; ASTM A370 covers mechanical testing of steel; ASTM D638 and ISO 527 address plastics; ASTM E21 and ISO 6892-2 are for high-temperature tests on metals; ASTM D3039 is for polymer matrix composites; ISO 37 is for rubber, and ASTM F606 is for fasteners.
In addition to these 10 most common standards from ASTM and ISO, there are other popular standards for tensile testing. Among them are JIS Z 2241 - Methods of Tensile Testing for Metallic Materials, BS EN 10002-1 - Tensile Testing of Metallic Materials at Ambient Temperature, and ASTM D882 - Standard Test Method for Tensile Properties of Thin Plastic Sheeting. While these standards did not make our list this time, they will be reviewed in future discussions.
The need for high-tech equipment is one of the most common requirements among these standards. If you are looking for reliable tools for tensile testing and specimen preparation, consider our TensileMill CNC MINI for flexible, precise flat sample preparation, and our Servo-Hydraulic Universal Testing System for high-force mechanical testing. These systems will provide you with high-quality measurements that you can trust.
At TensileMill CNC, we support all your tensile testing needs, not just with equipment but with comprehensive services. Get a free quote online or contact us directly if you have any questions or would like to learn more about what we offer.