Advances in Small Specimen Testing Methods for Characterizing Tensile, Creep, and Fracture Properties of Materials
Tensile, impact, and creep properties of materials are evaluated using standard test methods following ISO, ASTM, and other international testing standards. These testing methods use large specimens and are material-intensive. Three innovative small speci
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Advances in Small Specimen Testing Methods for Characterizing Tensile, Creep, and Fracture Properties of Materials M.D. Mathew
Abstract Tensile, impact, and creep properties of materials are evaluated using standard test methods following ISO, ASTM, and other international testing standards. These testing methods use large specimens and are material-intensive. Three innovative small specimen testing methods, namely impression creep (IC), small punch creep (SPC), and ball indentation (BI), are discussed that can be used to determine the mechanical properties of materials. IC is used to study the creep deformation behaviour of materials. SPC is used to evaluate creep deformation and fracture properties of materials. Tensile and hardness properties and fracture toughness can be evaluated using BI method. Unlike in conventional testing methods, all these small specimen testing methods involve complex stresses which are also heterogeneous. Therefore, there is a certain amount of empiricism while characterizing mechanical properties using these methods. However, being material non-intensive, these methods have applications and advantages over conventional methods namely in material development, material performance evaluation, and characterization of mechanical properties of weld joints. This paper presents a comprehensive review of the recent advances in IC, SPC, and BI testing techniques and discusses their relative advantages and limitations. Keywords Impression creep Weld joint 316L(N) SS
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Ball indentation
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Small punch creep
M.D. Mathew (✉) Saintgits College of Engineering, Kottayam 686532, Kerala, India e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2018 M. Muruganant et al. (eds.), Frontiers in Materials Processing, Applications, Research and Technology, https://doi.org/10.1007/978-981-10-4819-7_19
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M.D. Mathew
1 Introduction Evaluation of mechanical properties of materials is usually performed from destructive mechanical tests such as tensile, creep, and impact tests using bulk samples and as per the international testing standards. These test methods are material-intensive. Further, it is not possible to characterize the mechanical properties of narrow microstructural zones in weldments using these standard test methods. Several innovative small specimen testing techniques have been under development for evaluation of mechanical properties of materials. When compared with standard mechanical tests, these testing techniques are especially useful for optimizing the chemical composition in any alloy development programme since rapid screening of mechanical properties can be done using small size laboratory heats of material. Despite these advantages, the techniques have limitations: (i) Loading mode is usually compressive or bending unlike the conventional mechanical tests in which the loading mode is tensile, (ii) the test time is generally short and so the influence of long-term microstructural changes that occur in alloys at high temperature cannot be understood, and (iii)
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