5.1 The U-bend specimen may be used for any metal alloy sufficiently ductile to be formed into the U-shape without mechanically cracking. The specimen is most easily made from strip or sheet but can be machined from plate, bar, castings, or weldments; wire specimens may be used also.5.2 Since the U-bend usually contains large amounts of elastic and plastic strain, it provides one of the most severe tests available for smooth (as opposed to notched or precracked) stress-corrosion test specimens. The stress conditions are not usually known and a wide range of stresses exist in a single stressed specimen. The specimen is therefore unsuitable for studying the effects of different applied stresses on stress-corrosion cracking or for studying variables that have only a minor effect on cracking. The advantage of the U-bend specimen is that it is simple and economical to make and use. It is most useful for detecting large differences between the stress-corrosion cracking resistance of (a) different metals in the same environment, (b) one metal in different metallurgical conditions in the same environment, or (c) one metal in several environments.1.1 This practice covers procedures for making and using U-bend specimens for the evaluation of stress-corrosion cracking in metals. The U-bend specimen is generally a rectangular strip that is bent 180° around a predetermined radius and maintained in this constant strain condition during the stress-corrosion test. Bends slightly less than or greater than 180° are sometimes used. Typical U-bend configurations showing several different methods of maintaining the applied stress are shown in Fig. 1.FIG. 1 Typical Stressed U-bends1.2 U-bend specimens usually contain both elastic and plastic strain. In some cases (for example, very thin sheet or small diameter wire) it is possible to form a U-bend and produce only elastic strain. However, bent-beam (Practice G39 or direct tension (Practice G49)) specimens are normally used to study stress-corrosion cracking of strip or sheet under elastic strain only.1.3 This practice is concerned only with the test specimen and not the environmental aspects of stress-corrosion testing, which are discussed elsewhere (1)2 and in Practices G35, G36, G37, G41, G44, G103 and Test Method G123.1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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5.1 The mandrel bend test is simple and fast. It requires little investment in equipment and little operator training. The prime purpose is to determine whether a film of adhesive coated on a substrate meets flexibility requirements. The test is also useful for comparing flexibility of adhesives. It can be used to design adhesives by comparing the flexibility of various formulations to meet specific end-use parameters. The adhesive flexibility can be determined at temperatures other than ambient by conditioning the test apparatus and test specimen at the desired temperature and performing the test under those conditions.FIG. 1 Test Mandrel (Various Diameters) for Test FrameNOTE 1: Figures in parentheses are approximate.1.1 This test method covers the determination of the flexibility of an adhesive film bonded to a flexible substrate. The results are useful for comparing flexibility of adhesives and not for absolute characterization of adhesives.1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for information purposes only.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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5.1 This bend test provides information as to the formability or the ability of copper and copper alloy strip to resist cracking when being formed.5.2 This test method can be used as a quality control tool to determine if material will form to a given radius.5.3 This test method is also useful in research and development to provide data for use in selecting a spring material that will safely form to the geometry of a given part.5.3.1 The forming characteristic of interest is the smallest bend radius that can be formed without cracks or otherwise unacceptable surface conditions (8.4). This radius, R, is the radius of curvature of the nose of the punch used in the test.5.3.2 In addition, the difference between the angle of the bend after testing and 90° provides a measure of post-forming springback.5.4 The results are suitable for direct application in design and manufacturing, only when all factors such as the geometry of the part, punch and die design, lubrication, stamping speed, and other material properties are known.1.1 This test method covers the technique of bend testing copper and copper alloy strip samples to determine product formability or the ability to resist cracking when forming a bend around a specific radius. The criterion for failure is the occurrence of cracks on the convex surface of the bend.1.2 This bend test is limited to strip from 0.003 in. to and including 0.031 in. (0.076 mm to and including 0.79 mm) thick.1.3 The forming or punch radius for the bend test shall be determined by agreement between the manufacturer or supplier and purchaser. This punch radius is typically equal to or greater than the minimum bend radius without failure for the alloy, temper and thickness combination of the strip being tested.1.4 Units—The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units which are provided for information only and are not considered standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 515元 / 折扣价： 438 元 加购物车

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