ASTM E209-00(R2005)

Designation: E 209 – 00 (Reapproved 2005) Standard Practice for Compression Tests of Metallic Materials at Elevated Temperatures with Conventional or Rapid Heating Rates and Strain Rates1 This standard is issued under the fixed designation E 209; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval. 1. Scope 1.1 This practice covers compression test in which the specimen is heated to a constant and uniform temperature and held at temperature while an axial force is applied at a controlled rate of strain. NOTE 1—In metals with extremely high elastic limit or low modulus of elasticity it is conceivable that 1.5 percent total strain under load could be reached before the 0.2 percent-offset yield strength is reached. In this event the 0.2 percent-offset yield strength will be the end point of the test unless rupture occurs before that point. NOTE 2—For acceptable compression tests it is imperative that the specimens not buckle before the end point is reached. For this reason the equipment and procedures, as discussed in this recommended practice, must be designed to maintain uniform loading and axial alignment. 1.2 Preferred conditions of testing are recommended so that data from different sources conducting the tests will be comparable. 1.3 The values stated in inch-pound units are to be regarded as the standard. 1.4 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 appro- priate safety and health practices and determine the applica- bility of regulatory limitations prior to use. 2. Referenced Documents 2.1 ASTM Standards: 2 E 4 Practices for Force Verification of Testing Machines E 9 Test Methods of Compression Testing of Metallic Ma- terials at Room Temperature E 21 Test Methods for Elevated Temperature Tension Tests of Metallic Materials E 83 Practice for Verification and Classification of Exten- someter System 3. Apparatus 3.1 Testing Machines—Machines used for compression test- ing shall conform to the requirements of Practices E 4. 3.2 Bearing Blocks and Loading Adapters—Load both ends of the compression specimens through bearing blocks or through pin-type adapters that are part of the compression- testing assembly. Bearing blocks may be designed with flat bearing faces for sheet- or bar-type specimens. Sheet speci- mens may also be loaded through pin-type adapters that are clamped rigidly to the grip sections of specimens designed for these adapters (1).3 The main requirement is that the method of applying the force be consistent with maintaining axial align- ment and uniform loading on the specimen throughout the test. When bearing blocks with flat faces are used, the load-bearing surfaces should be smooth and parallel within very close limits. The tolerance for parallelism for these surfaces should be equal to or closer than that specified for the loaded ends of the specimens. The design of the equipment should provide adequate rigidity so that parallelism is maintained during heating and loading. The bearing blocks or pin-type adapters should be made of a material that is sufficiently hard at the testing temperature to resist plastic indentation at maximum force. They should also be of a material or coated with a material that is sufficiently oxidation resistant at the maximum testing temperature to prevent the formation of an oxide coating that would cause misalignment. In any compression test it is important that the specimen be carefully centered with respect to the bearing blocks, which in turn should be centered with respect to the testing machine heads. NOTE 3—Bearing blocks with straight cylindrical or threaded holes depending on specimen design may be used for bar-type specimens providing the apparatus qualifies in accordance with Section 9. NOTE 4—Bearing blocks of an adjustable type to provide parallel loading surfaces are discussed in Test Methods E 9. Bearing blocks with 1 This practice is under the jurisdiction of ASTM Committee E28 on Mechanical Testing and is the direct responsibility of Subcommittee E28.10 on Effect of Elevated Temperature on Properties. Current edition approved Dec. 1, 2005 Published December 2005. Originally approved in 1963. Last previous edition, approved in 2000 as E209–00e1. 2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website. 3 Boldface numbers in parentheses refer to references at the end of this practice. 1 Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States. Copyright by ASTM Int'l (all rights reserved); Reproduction authorized per License Agreement with Monique Tyree (ASTMIHS Account); Mon Jan 30 15:41:06 EST 2006 Copyright ASTM International Provided by IHS under license with ASTM Licensee=Defense Supply Ctr/5913977001 Not for Resale, 01/09/2008 05:37:14 MSTNo reproduction or networking permitted without license from IHS - - ` ` , , ` ` ` ` ` , ` , ` ` , ` ` ` ` , , ` , , , ` ` , , ` - ` - ` , , ` , , ` , ` , , ` - - - a spherical seat for the upper block are also shown. 3.3 Subpresses—A subpress or other alignment device is necessary in order to maintain suitable alignment when testing specimens that are not laterally supported, unless the testing machine has been designed specifically for axial alignment and uniform application of force in elevated-temperature compres- sion testing. A subpress for room-temperature testing is shown in Test Methods E 9. For elevated-temperature compression testing, the subpress must accommodate the heating and loading devices and the temperature-sensing elements. The design of the subpress is largely dependent on the size and strength of the specimens, the temperatures to be used, the environment, and other factors. It must be designed so the ram does not jam or tilt the frame as a result of heating or application of force. If the bearing faces of the subpress, the opposite faces of both bearing blocks, and the ends of the specimen are respectively plane and parallel within very close limits, it is unnecessary to use adjustable or spherical seats. In any case, the specimen should be properly centered in the subpress. 3.4 Compression Testing Jigs—When testing sheet material, buckling of the specimen during application of compessive forces must be prevented. This may be accomplished by using a jig containing side-support plates that bear against the faces of the specimen. The jig must afford a suitable combination of lateral-support pressure and spring constant to prevent buck- ling without interfering with axial deformation of the specimen (1). Although suitable combinations vary somewhat with variations in specimen material and thickness, testing tempera- ture, and accuracy of alignment, acceptable results can be obtained with rather wide ranges of lateral-support pressure and spring constant for any given test conditions. Generally, the higher the spring constant of the jig, the lower the lateral-support pressure that is required. Proper adjustment of these test variables may be established in preliminary verifi- cation tests for the equipment (Section 9). 3.4.1 This practice does not intend to designate specific compression jigs for testing sheet metals, but merely to provide a few illustrations and references to jigs that have been used successfully. Many other jigs are acceptable provided they prevent buckling and pass the qualification tests set forth in Section 9. Satisfactory results have been obtained in room- temperature testing using the jigs illustrated in Test Methods E 9. These jigs usually require that the specimen be lubricated to permit normal compression on loading. For elevated- temperature testing, modified jigs that accommodate the heat- ing and strain-measuring equipment as well as the temperature- sensing elements must be used. A number of compression- testing jigs have been evaluated specifically for performance in elevated-temperature tests (2, 3). The preferred type depends on the material, its thickness, and the temperatures involved. For moderately elevated temperatures, one of the room- temperature designs may be used in an oven in which the air is circulated to provide uniform heating. One design for side- support plates that has been found satisfactory for use at temperatures up to 1000°F (538°C) when lubricated with graphite is shown in Fig. 1( a) (4). Longitudinal grooves are cut in each plate with the grooves offset across the thickness of the specimen. These plates are made of titanium carbide. A type of side-support plate that has been used in compression jigs to 1800°F (982°C) is shown in Fig. 1(b) (4). This is an assembly of small titanium carbide balls backed up by a titanium carbide plate. The balls protrude through holes in the front retaining plate. The holes for the balls are large enough to allow rotation and translation of each ball while at the same time retaining the balls in the plate assembly. The spacing of the balls, which is normally about 1⁄8 in. (3.2 mm), determines the minimum specimen thickness that can be tested without buckling be- tween the balls. Rational values of the ball spacing can be obtained from calculations based upon the plastic buckling of simply supported plates where the plate width can be taken as the ball spacing. Another type of jig has a number of leaf- spring supports on each side of the specimen (3, 5). This design is limited to a temperature range in which the metal leaf-spring elements can support the specimen satisfactorily. Jigs for use with specimens that are heated by self resistance are discussed in Ref 1, 6 and 7, which also provide quantitative information on the effects of lubrication, lateral-support pressure, spring constant, and misalignment. 3.4.2 The side-support plates are assembled in a frame that is part of the jig. A typical frame and jig assembly is shown in Fig. 2. A furnace is placed around the jig after the specimen and extensometer are assembled in the jig. The holes in the support blocks are for auxiliary cartridge-type heaters. 4. Heating Apparatus 4.1 The apparatus and method for heating the specimens are not specified, but in present practice the following are mainly used. 4.1.1 The resistance of the specimen gage length to the passage of an electric current, 4.1.2 Resistance heating supplemented by radiant heating, 4.1.3 Radiant heating, 4.1.4 Induction heating, or 4.1.5 Convection heating with circulating-air furnace. 4.2 The apparatus must be suitable for heating the specimen under the conditions specified in Section 5. 5. Test Specimen 5.1 The size and shape of the test specimen should be based on three requirements as follows: FIG. 1 Specimen Side Support Plates (Ref 4) E 209 – 00 (2005) 2 Copyright by ASTM Int'l (all rights reserved); Reproduction authorized per License Agreement with Monique Tyree (ASTMIHS Account); Mon Jan 30 15:41:06 EST 2006 Copyright ASTM International Provided by IHS under license with ASTM Licensee=Defense Supply Ctr/5913977001 Not for Resale, 01/09/2008 05:37:14 MSTNo reproduction or networking permitted without license from IHS --``,,`````,`,``,````,,`,,,``,,`-`-`,,`,,`,`,,`--- 5.1.1 The specimen should be representative of the material being investigated and should be taken from the material produced in the form and condition in which it will be used, 5.1.2 The specimen should be adapted to meet the require- ments on temperature control and rates of heating and strain- ing, and 5.1.3 The specimen should be conducive to the maintenance of axial alignment uniform application of force, and freedom from buckling when loaded to the end point in the apparatus used. 5.2 The specimens are divided into two general classifica- tions: those with rectangular cross sections and those with round cross sections. The dimensions of the specimens are optional. The specimen must be long enough to be compressed to the required deformation without interference from a sup- porting jig but not long enough to permit buckling where it is unsupported. The end allowance (dimension between the gage points and the adjacent end of the uniform section) should be a minimum of one half the width of rectangular specimens or one half the diameter of round specimens. Typical acceptable specimens are illustrated in Fig. 3 and Fig. 4. 5.3 When the dimensions of the test material permit, round specimens should be used. Round specimens should be de- signed to be free from buckling up to the end point of the test without lateral support. Rectangular specimens up to 0.250 in. (6.35 mm) thick normally require lateral support; with greater thicknesses lateral support may not be required in well-aligned equipment. The methods covered by this specification are normally satisfactory for testing sheet specimens down to 0.020 in. (0.51 mm) thick. With smaller thicknesses inaccura- cies resulting from buckling and nonuniform straining tend to increase; consequently, extra care in the design, construction, and use of the test equipment is required to obtain valid results for specimens in this thickness range. All compression speci- mens should be examined after they are tested; any evidence of buckling invalidates the results for that specimen. 5.4 The width and thickness of rectangular specimens and diameter of round specimens at any point in the gage length should not vary from the average by more than 0.001 in. (0.025 mm) for dimensions up to 1 in. (25.4 mm) or by more than 0.1 percent for dimensions above 1 in. 5.5 The ends of end-loaded specimens should be parallel within 0.00025 in. (0.0064 mm) for widths, thicknesses, and diameters up to 1⁄2 in. (12.7 mm) and within 0.05 percent for widths, thicknesses, and diameters above 1⁄2 in. The ends of end-loaded specimens should be perpendicular to the sides within 1⁄4 of a degree. All machined surfaces should have an average surface finish of 63 µ in. or better. Rectangular FIG. 2 Typical Compression Testing Jig for Sheet Specimens Mounted on Support Jig (Ref 3) Dimensions Specimen 1 Specimen 2 Specimen 3 G.L.—Gage Length, in. (mm) 1.000 6 0.005 (25.46 0.13) 2.000 6 0.005 (50.86 0.13) 2.000 6 0.005 (50.86 0.13) L—Uniform Section, in. (mm) 2.500 6 0.005 (63.56 0.13) 3.000 6 0.005 (76.26 0.13) 2.50 min (63.5) W—Width, in. (mm) 0.625 6 0.010 (15.96 0.25) 1.000 6 0.010 (25.46 0.25) 0.500 6 0.010 (12.76 0.25) E.A.—End Allowance, in. (mm) 0.75 (19) 0.50 (12.7) 0.25 min (6.35) FIG. 3 Dimensions of Typical Rectangular Specimens E 209 – 00 (2005) 3 Copyright by ASTM Int'l (all rights reserved); Reproduction authorized per License Agreement with Monique Tyree (ASTMIHS Account); Mon Jan 30 15:41:06 EST 2006 Copyright ASTM International Provided by IHS under license with ASTM Licensee=Defense Supply Ctr/5913977001 Not for Resale, 01/09/2008 05:37:14 MSTNo reproduction or networking permitted without license from IHS - - ` ` , , ` ` ` ` ` , ` , ` ` , ` ` ` ` , , ` , , , ` ` , , ` - ` - ` , , ` , , ` , ` , , ` - - - specimens should have a width of material, equal to at least the thickness of the specimen, machined from all sheared or stamped edges. 5.6 Shouldered specimens may be used in lieu of specimens with uniform width or diameter, provided the method of applying force is consistent with requirements of axial align- ment, uniform application of force, and freedom from buck- ling. 5.7 The surfaces of the rectangular specimens in contact with the supporting jig should be lubricated to reduce friction. The lubricant should have negligible reaction with the surface of the specimen for the test temperature and time chosen and should retain its lubricating properties for the duration of the test. Molybdenum disulfide and graphite are examples of lubricants that are used. 5.8 Specimen dimensions above 0.100 (2.54 mm) in. should be measured to the nearest 0.001 in. (0.025 mm) or less; dimensions under 0.100 in. should be measured to the nearest 1 percent or less. The average cross-sectional area of the gage length should be used for calculation of stress. 6. Temperature Control 6.1 Conventional Heating—When a conventional-heating rate is desired, variations in indicated temperature within the gage length of the specimen should not exceed the following limits during a test: Test Temperature Allowable Variation, deg F (deg C), plus and minus Up to and including 1800°F (982°C) 5 (3) Over 1800°F (982°C) up to and including 2800°F (1538°C) 10 (5.5) Over 2800°F (1538°C) up to and including 3500°F (1927°C) 20 (11) Over 3500°F (1927°C) 35 (19.5) The time of heating and holding prior to the start of the stressing should be governed by the time necessary to ensure that the temperatures can be maintained as specified. If compression tests are being made as the counterpart to tension test under Practice E 21, the heating time and holding time in both types of tests should be the same. The heating and holding time actually used should be reported. 6.2 Rapid Heating—When a rapid heating rate is desired, the preferred conditions for heating the gage length of the specimen are as follows: 6.2.1 Sixty seconds or less to heat to the indicated nominal test temperature, and 6.2.2 Holding time at the indicated nominal test temperature before applying the force equal to the heating time. 6.2.3 The indicated control temperature of the specimen should not vary more than 610°F (5.5°C) from the nominal test temperature up to and including 1000°F (538°C) and not more than 61.0 % of the nominal test temperature above 1000°F. The uniformity of temperature within the specimen gage length should be within + 10°F and − 20°F (11°C) of the nominal test temperature up to and including 1000°F and within + 1.0 and − 2.0 % of the nominal test temperature above 1000°F. NOTE 5—It is recognized that true temperatures will vary more than the indicated temperatures. The permissible indicated temperature variations specified in 6.1 and 6.2 are not to be construed as minimizing the importance of good pyrometry practice and accurate temperature control in these tests. All laboratories are obligated to keep both indicated and true temperature variations as small as practicable. In view of the extreme dependency of strength of materials on temperature, close temperature control is necessary. The limits prescribed represent ranges that are common practice. For further information on pyrometric practices refer- ence should be made to the “Panel Discussion on Pyrometric Practices.” 4 6.3 In rapid-heating tests a maximum overshoot in the indicated temperature during the heating and holding period of 20°F or 2.0 % of the nominal test temperature, whichever is greater, is allowed for a time not exceeding 30 s. The overshoot limitation permits a larger temperature variation for a 30-s period prior to testing than permitted for conventional-heating tests, for which no overshoot in temperature beyond the allowable variations in 6.1 is allowed. 4 Panel Discussion on Pyrometric Practices, ASTM STP 178, Am. Soc. Testing Mats. (1955). Dimensions Specimen 1 Specimen 2 Specimen 3 G.L.—Gage Length, in. 1.000 6 0.005 (25.46 0.13) 2.000 6 0.005 (50.86 0.13) 1.000 6 0.005 (25.46 0.13) L—Uniform Section, in. 1.500 6 0.005 (38.16 0.13) 3.375 6 0.05 (85.86 1.27) 1.500 6 0.005 (38.16 0.13) D—Diameter, in. 0.500 6 0.010 (12.76 0.25) 1.125 6 0.010 (28.66 0.25) 0.375 6 0.010 (9.56 0.25) E.A.—End Allowance, in. 0.25 (6.35) 0.69 (17.5) 0.25 (6.35) NOTE 1—S