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[ISO] ASTM E8, ISO 6892, KS B 0801 - Tensile Testing Metals
Writer : 관리자(salt@light-salt.kr)   Date : 21.06.22   Hit : 1269
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Tensile Tests on Metal


ASTM E8: Standard Test Methods for TensileTesting of Metallic Materials

ISO 6892, KS B 0801: Metallic materials ?Tensile Testing ? Part 1: Method of tests at room temperature

 

Tensile testing is the most common test method for measuring the material properties of metallic materials such as steel, iron, alloys in various shapes and forms such as bolts, rebars, wires etc. The point of these tests are often to see the values for Ultimate Tensile Strength (Peak strength), Elongation % (Strain or deformation), Yield Point (Point of permanent deformation), Reduction of Area (Change in original cross-sectional area) etc. Some of these measurements for elongation and yield often require specialized strain measurement tools such as extensometers. ASTM E8 and ISO 6892 as well as some similar standards are the most recognized and used standards in the tensile testing of metals.

 

Mechanical Testing Equipment


In ASTM E8 Section 5.Apparatus the standard goes into detail of the machines and parts used for testing and measurement. ASTM E4 calibration for the testing machine is required for force verification. Extensometers used in conjunction are mentioned as well, “extensometers shall conform to the requirements of Practice E83” The standard also lists standardized testing shapes for threaded specimen, collard specimen, plate/flat specimen as well as other shapes like the pin-loaded tension test specimen. These standardized shapes are critical as they often determine which grips or accessories are required for the testing set-up.

 


 

Grips and Accessories

As explained in the standards, grips are accessories are dependant on the specimen. Grips come in many different shapes, sizes and gripping methods. Ranging from your manual wedge action grips, pneumatic grips, pin grips, threaded grips etc.

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The most standard and commonly used grips are the wedge action grips. Wedge action grips work well with most metals as the mechanism is designed to tighten it's grip during the tensile test. Our tensile grips can be fitted with specific jaw faces for the specimen to be tested.


Steel rebar tested with wedge action grips


 

Terms and Symbols


In ISO-6892-1Section 4 Terms and symbols ? Table 1 gives a very simplistic breakdown ofall the commonly used symbols when testing and measuring metallic materials.Some common used symbols that are used in material property testing Original gauge length is Lo (mm), Extension at fracture ΔLf (mm), Percentage yield point extension Ae (%), Maximum force Fm (N), Modulus of elasticity E (MPA)etc.

 

All these values are measured and calculated by our Salt_UTM software

 

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 Many tensile tests are done at a fixed speed (mm/min) but some tests do require strain rate control in conjunction with a strain measurement device. 

 

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