ASTM E8 and ASTM F606 are both standards for tensile testing, but they are used for different purposes and specific scenarios when testing an ASTM A325 bolt.
1. Use ASTM F606 for Structural Bolts (Preferred Standard for A325 Bolts):
- ASTM F606 is specifically designed for the mechanical testing of fasteners, including bolts like ASTM A325. It covers various tests including tensile strength, yield strength, proof load, and hardness tests for both the bolt and the nut.
- ASTM F606 is the primary standard for testing A325 bolts because it includes provisions for tensile testing while considering the bolt’s dimensions and structural characteristics.
2. When to Use ASTM E8 Instead of F606:
- ASTM E8 is a general tensile testing standard for metals. It provides a detailed methodology for determining the tensile properties of materials, specifically focusing on test specimens that may need to be machined or prepared before testing.
- You may need to use ASTM E8 when the bolt’s length exceeds what can be effectively tested under ASTM F606, particularly for longer bolts where the shank is too long for the testing equipment.
- ASTM E8 applies when testing involves a machined specimen taken from the bolt. For example, when the A325 bolt is too long, and it’s necessary to machine the bolt (cut out a portion of it) to create a specimen that fits the tensile test equipment. This is done to ensure proper stress distribution and accurate measurement of mechanical properties like tensile strength, yield strength, and elongation.
Example Scenario:
- If you are testing an ASTM A325 bolt that is too long to be directly tested using the provisions in ASTM F606, such as when the bolt must fit into a tensile testing machine, you can machine the bolt down to a suitable size and apply ASTM E8 procedures to test it. The results will then provide accurate tensile properties of the base material.
Summary:
- Use ASTM F606 for standard testing of ASTM A325 bolts, which covers most structural bolting tests.
- Use ASTM E8 when the bolt is too long or if you need to test a machined specimen (such as when you need to follow the E8 testing procedure for elongated bolts).
This ensures proper application of each standard based on the length, size, and testing constraints of the A325 bolt.
Additional Info:
In ASTM E8, when a bolt or any metal specimen is modified or reduced in size for tensile testing, this is referred to as preparing a “machined specimen.” The bolt or metal is machined to fit into the testing equipment and to meet the dimensional requirements of a tensile test specimen.
The specific term used in ASTM E8 for cutting and preparing the test specimen is “sub-size specimen” or “reduced section specimen”. These specimens are typically taken from the shank of the bolt or another part of the fastener, with the goal of ensuring that the testing occurs on the base material (not the threaded section) under controlled conditions.
- Sub-size Specimen: This refers to a smaller version of the standard tensile test specimen when the full-size specimen cannot be tested due to size constraints of the bolt or equipment.
- Reduced Section: This indicates the portion of the bolt that is machined down to specific dimensions, especially for long bolts that exceed standard testing machine capacities.
This process allows the tensile test to be conducted in a way that simulates the material properties of the bolt without interference from non-uniform stress areas, such as threads.