ASTM A370 Test method and definitions for mechanical testing of steel
ASTM A370 is an internationally recognized and comprehensive collective standard that generally deals with the mechanical testing of steel products and is used in various industries such as construction, mechanical engineering, automotive, and aerospace. It ensures that steel products meet the high requirements for strength, ductility and safety and provides a reliable basis for industry, research and quality assurance.
In order to determine the required material properties in accordance with the product specifications, ASTM A370 describes various test methods such as the tensile test, flexure test, hardness testing to Brinell, Rockwell and portable hardness testing as well as the Charpy impact test. The focus of ASTM A370 is primarily on tensile testing.
The following content explains the key aspects. For standard-compliant testing in accordance with ASTM A370, however, it is essential to purchase the complete standard.
Standards references Tensile test Flexure test Hardness testing Charpy impact test Annexes FAQ Customer projects
References to additional standards in ASTM A370
ASTM A370 specifies the basic test methods for mechanical testing of steel products and refers to other test standards from the ASTM standards catalog. It should be noted that the “A-standards” in the ASTM standards such as ASTM A370 refer to iron and steel materials (“A” for “ferrous metals”). In contrast, E-standards such as ASTM E8 generally refer to test methods and practices (“E” for “test methods and practices”).
Differences between ASTM A370 and the respective specified ASTM standards include the specimen geometry.
In addition to the relevant ASTM standards, the respective ISO standards that are relevant in combination with ASTM A370 are also included in the table.
| Test methods in ASTM A370 | Reference to ASTM standard | Counterpart in the ISO standard |
|---|---|---|
| Tensile test at ambient temperature | ||
| Flexure test | ASTM E290 ASTM E190 | |
Rockwell hardness Brinell hardness Vickers hardness | ||
| Charpy impact test |
Tensile test to ASTM A370
The tensile test is a key method for determining the mechanical properties of steel and other materials. A standardized specimen is tested under increasing tensile load until it breaks.
The tensile test according to ASTM A370 determines the following material properties in particular:
- Elasticity module E: Degree of resistance of a material to elastic deformation
- Yield point Re and Rp0.2: Permanent deformation of the material or plasticization.
- Tensile strength Rm: Maximum mechanical tensile stress that can be applied with which the material can be loaded. In addition, point of maximum force.
The most important characteristic values that are determined are the yield point, tensile strength und strain at break. These values provide information about the behavior of the material under load and are decisive for the selection of materials for a wide range of applications, such as in the automotive industry, mechanical engineering, or aerospace.
The tensile test at ambient temperature is performed in accordance with internationally standardized standards such as ASTM E8 or ISO 6892-1. The specimen is subjected to quasi-static tensile stress while force and strain are measured continuously. The yield point indicates the point at which the material begins to deform plastically, the tensile strength the maximum load that the material can withstand. Strain at break describes the ability of the material to deform plastically before breaking.
In addition to these characteristic values at room temperature, the tensile test can also be carried out in other variants, such as at elevated temperatures as in ASTM E21 or ISO 6892-2 to test the behavior of materials in specific areas of application. These tests are crucial for the quality assurance of steel products and help to ensure the suitability of materials for various industrial applications.
ZwickRoell's testing machines work with electromechanical loading systems and enable precise control of the testing speed.
ASTM A370 Tensile test on specimens and dimensions
ASTM A370 specifies the use of flat or round specimens for the tensile test. Below is a comparison of the dimensions of the specimens with ASTM E8. The following table shows the standardized specimen dimensions for flat specimens according to ASTM A370. The standard describes three different specimen types, which differ in sheet thickness. These are flat tensile specimens made of sheet metal (“sheet type”), “plate type” specimens made of heavy plate, among others, and “subsize specimens”.
Compared to ASTM E8, it can be seen that only the subsize specimens differ slightly in the width of the specimen in the metric system. ASTM E8 offers several other specimen geometries with different gauge lengths that are not mentioned in ASTM A370.
Overall, it can be stated that the specimen geometry between ASTM A370 and ASTM E8 (M) is very similar for flat and round specimens in the tensile test. However, there are differences - especially in the metric system, which should be taken into account when using it.
Flat specimens
| Category | Sheet thickness | Type of measurement | ASTM A370 | ASTM E8 |
|---|---|---|---|---|
| Flat tensile specimen “sheet type” | 1 in (max. 25 mm) | Gauge length (G) | 2.0 in (50 mm) | 2.0 in (50 mm) |
| Width (W) | 0.5 in (12.5 mm) | 0.5 in (12.5 mm) | ||
| Heavy plate specimen “Plate type I” | 3⁄16 in (min. 5 mm) | Gauge length (G) | 8.0 in (200 mm) | 8.0 in (200 mm) |
| Width (W) | 1.5 in (40 mm) | 1.5 in (40 mm) | ||
| Heavy plate specimen “Plate type II” | 3⁄16 in (min. 5 mm) | Gauge length (G) | 2.0 in (50 mm) | 2.0 in (50 mm) |
| Width (W) | 1.5 in (40 mm) | 1.5 in (40 mm) | ||
| Smallest specimen “Subsize specimen” | 1⁄4 in (max. 6 mm) | Gauge length (G) | 1.0 in (25 mm) | 1.0 in (25 mm) |
| Width (W) | 0.25 in (6.25 mm) | 0.25 in (6.0 mm) |
Round specimens
ASTM A370 also specifies specimen geometries for round specimens: The following table shows the standardized specimen dimensions for round specimens according to ASTM A370. The standard describes various specimen types that differ in their specimen radius and diameter. The parallel length ("length of reduced section") also varies. The exact differences can be found in the table below. In comparison to ASTM E8, the values differ primarily in their translation into the metric system, but also in the area of the gauge length. This primarily affects Standard Specimen 2 and Small-size Specimen 1.
| Category | Type of measurement | ASTM A370 (in) | ASTM A370 (mm) | ASTM E8 (mm) |
|---|---|---|---|---|
| Standard specimen “Standard Specimen 1” | Gauge length G | 2.0 | 50.0 | 50.0 |
| Fillet radius R | 3/8 | 10.0 | 10.0 | |
| Parallel length A (reduced section length) | 2.25 | 60.0 | 56.0 | |
| Standard specimen “Standard Specimen 2” | Gauge length G | 1.4 | 35.0 | 36.0 |
| Fillet radius R | 0.25 | 6.0 | 8.0 | |
| Parallel length A (reduced section length) | 1.75 | 45.0 | 45.0 | |
| “Small-size Specimen 1” | Gauge length G | 1.0 | 25.0 | 24.0 |
| Fillet radius R | 3/16 | 5.0 | 6.0 | |
| Parallel length A (reduced section length) | 1.25 | 32.0 | 30.0 | |
| “Small-size Specimen 2” | Gauge length G | 0.64 | 16.0 | 16.0 |
| Fillet radius R | 5/32 | 4.0 | 4.0 | |
| Parallel length A (reduced section length) | 0.75 | 20.0 | 20.0 |
Specimen grips and exensometers for tensile tests to ASTM A370
Precise measurement and stable fixing of the specimens are crucial for performing tensile tests in accordance with ASTM A370. Our specially developed specimen grips ensure secure and reliable fastening of the steel specimens, creating realistic test conditions. This ensures that the specimen remains stable throughout the test without affecting the mechanical properties.
In addition, our high-precision extensometers ensure exact measurement of strain and make it possible to determine important characteristic values such as yield strength, modulus of elasticity and strain at break. The non-contact extensometers in particular record even the smallest strains with maximum accuracy.
With the help of innovative solutions, we ensure that your tests meet the highest standards and deliver precise, reproducible results. This contributes significantly to quality assurance and the sound evaluation of the material properties of steel products.
Flexure test to ASTM A370
The flexure test is a proven method for evaluating the ductility of steel and metals. The specimen is bent to a defined angle around a specific internal diameter. The test depends on factors such as the bending angle, cross-section, chemical composition, tensile strength, and hardness of the steel.
The test methods are based on the ASTM E190 and E290 standards. The test is usually performed at ambient temperature, whereby the bending speed, if sufficiently slow (quasi-static), does not play a significant role.
Other standards for flexure tests are ISO 7438 and ISO 8491.
Our modern ZwickRoell testing machines and strict quality controls enable us to deliver reliable and standard-compliant results for your steel products.
Hardness testing to ASTM A370
The hardness test generally measures the resistance of materials to penetration by a geometric body and serves as a comparatively simple and quick method for estimating the strength of a material. The hardness test also serves as an approximation of the tensile strength since there is a correlation between the two. This relationship is particularly well researched for steels and makes it possible to estimate the tensile strength if a direct tensile test cannot be performed. ASTM A370 refers specifically to the testing of steel.
Depending on the specific requirements, different test methods for hardness are used in ASTM A370:
- Rockwell (to ASTM E18): Ideal for hardened steels, comparatively fast measurement
- Brinell (to ASTM E10): Suitable for soft to medium-hard metals, larger indentations
- Portable hardness testers – Flexible for large or immovable workpieces
The test results can be converted into other hardness scales or into a strength using conversion tables. In the documentation, the measured hardness value is specified together with its scale, e.g. 353 HBW or 38 HRC
ZwickRoell’s precise hardness testing machines guarantee reliable and standard-compliant hardness measurements for various steel products.
ASTM A370 Charpy impact test
TheCharpy impact test (also according to ASTM E23) is a dynamic test method for determining the ductility of a material under impact load. A notched specimen is subjected to an impact load in a pendulum impact tester. The test values determined include:
- The absorbed energy of the specimen – a measure of the material's resistance to sudden loads and the classification between brittle and ductile.
- The percentage shear fracture – to assess the type of fracture (brittle or ductile)
- The lateral expansion on the notch side – an assessment of the material deformation
The Charpy notched bar impact test is also described in detail in ISO 148-1.
The Izod notched bar impact test, as described in ASTM E23, is only briefly mentioned in this context in ASTM A370, but is not dealt with in detail. There is no detailed explanation of the test method, its execution, or the specific requirements to be observed.
Annex 1: Steel bar products
The quality assurance of bars and rods is conducted using specific test methods that go beyond the general specifications. Tensile tests are not required for steel bars with a diameter of less than 13 mm, but can be performed if necessary. Flexure tests are performed differently depending on the manufacturing process (hot-rolled or cold-rolled). For hardness testing, a layer of material may need to be removed to ensure accurate results. These tests ensure that steel bars meet the high mechanical requirements and that their quality is reliably checked.
Annex 2: Steel tubular products
Testing of steel tubes or pipes covers a variety of shapes, including round, square, rectangular, and special profiles. The tensile test is performed on complete tube sections, longitudinally cut strip specimens, and ring specimens cut from the tube wall (ring tensile test). The specimens are loaded axially or radially to determine mechanical properties such as tensile strength, yield point, and strain at break.
Hardness tests are carried out on the inside or outside of the tubes as well as in the cross-section. A lower test force is used for thin-walled tubes in order to avoid deformation. Additional tests are performed to determine ductility, including the compression test on a ring specimen (crush test), flattening test, reverse flattening test, crushing test, flanging test, expansion test and tube-flattening test, which simulate various load scenarios. In addition, the hydraulic ring expansion test is used to determine the transverse yield strength and ensure that the tubes meet the necessary mechanical requirements.
Annex 3: Steel fasteners
For the testing of fasteners such as bolts, screws, and nuts, tensile tests are performed in which a minimum breaking load and proof load are checked. If required, bolts can be shortened to a standard length for use in the test method. Hardness tests on bolts and nuts are performed using either the Brinell or Rockwell method, depending on size and specification. For large nuts, a cross-sectional hardness test is performed to ensure that the fasteners function reliably even under extreme loads and meet the specified standards.
Annex 4: Steel round wire products
The testing of wire products includes tensile tests using wedge or wrap grips to correctly align the specimen. The wire diameter is measured to 0.025 mm at the breaking points. Strain is determined by measuring the distance between the breaking points. For wire products with a diameter of 2.5 mm or more, a hardness test is also performed. Ductility tests such as winding and spiral tests help to detect material defects and ensure that the wires continue to perform reliably under load.
Annex 5: Charpy impact tests
Charpy and Izod impact test are used to investigate the behavior of metals under impact load, whereby the brittleness and ductility under impact load are evaluated. These tests provide quantitative values that allow a comparison between different materials and manufacturing processes. The test illustrates at which temperature the material changes from ductile to brittle and thus helps to select materials for specialized applications. Particular attention must be paid to the correct test conditions for high-strength steels, as these can significantly influence the result. Despite the limitations, these tests are important tools for material selection and quality control.
ABOUT THE AUTHOR:
Dr. Harald Schmid
Global Industry Manager Metals | ZwickRoell GmbH & Co. KG
As Global Industry Manager, he is responsible for the industry strategy in the metals sector with a focus on market observation, further development of testing solutions and sales support in the international environment.
He has extensive experience in standardization work and is actively involved in various committees, including the international ISO committee ISO/TC 164 Mechanical Testing of Metals and national DIN working groups such as NA 062-01-42 AA Tensile and ductility testing for metals and NA 062-01-47 AA Impact test for metals and mechanical-technological testing of metallic pipes.
His academic career began with a degree in mechanical engineering (B.Sc. & M.Sc.) at the Karlsruhe Institute of Technology (KIT). After holding international positions in mechanical engineering, he worked as a research assistant at the Friedrich-Alexander-University Erlangen-Nuremberg with a focus on material characterization and sheet metal forming. He dedicated his doctorate to the topic of deep drawing processes with drawing beads.
Frequently asked questions regarding ASTM A370
ASTM A370 describes standardized test methods for the mechanical testing of steel products, including tensile, flexure, hardness, and notched bar impact tests to determine their mechanical properties. It ensures that steel products meet the high requirements for strength, toughness, and safety and provides a reliable basis for industry, research and quality assurance.
ASTM A370 covers various mechanical test methods for steel products, including tensile, bending, hardness, and impact tests to determine their mechanical properties.
In contrast, ASTM E8 focuses exclusively on the tensile test for metallic materials and specifies the test conditions, specimen geometries and evaluation methods for the determination of tensile strength, and yield point.