Superplasticity standards now available

Materials Science & Technology Division
31 Jan 2008

ISO and ASTM standards to measure the superplastic properties of materials are now in the public domain having been published for the first time in 2006 and 2007.

ISO 20032:2007 Method for evaluation of tensile properties of metallic superplastic materials specifies a method for evaluating the tensile properties of metallic superplastic materials which exhibit fine-grained superplasticity, without significant work-hardening or dynamic microstructure evolution, by means of a tensile test at constant cross-head velocity, for flat-form test pieces, without an extensometer attached.

ASTM E2448-06 Standard Test Method for Determining the Superplastic Properties of Metallic Sheet Materials specifies that the determination of the superplastic properties of a metallic sheet material is important for the observation, development and comparison of superplastic materials. It is also necessary to predict the correct forming parameters during an SPF process. SPF tensile testing has peculiar characteristics compared to conventional mechanical testing, which distort the true values of stress, strain, strain hardening, and strain rate at the very large elongations encountered in an SPF pull test, consequently conventional mechanical test methods cannot be used. This test method addresses those characteristics by optimizing the shape of the test coupon and specifying a new test procedure.

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