Application of Miniature Small Punch Test Specimen in Determination of Tensile Properties

Conventional tensile test methods are used for service exposed high temperature boiler tubes to evaluate the deterioration in mechanical properties such as tensile strength, yield strength and percentage elongation. The mechanical properties are required to be evaluated periodically as the boiler components undergo material degradation due to aging phenomena. The aging phenomena occurs due to continuous exposure of tubes to high temperature & pressure steam prevailing inside the tubes and high temperature exposure to corrosive combustible gases from the external surfaces within the boiler.A recent developed new technique called small punch testing has been used to evaluate the tensile properties of SA 213T22 grade steel predominantly exists in super-heater and re-heater sections of boiler. The small punch tests have been carried out on the miniature disk shaped specimens of diameter of 8.0 mm and 0.5 mm thickness extracted from both the new and service exposed tubes. Conventional uniaxial tensile tests on standard specimens from the same tube material have also been performed for comparison. The service exposed tubes showed considerable loss in mechanical properties in both the conventional and small punch test results. Correlations of tensile properties have been obtained based on the comparative analysis of both small punch and uniaxial tensile test results. Further, the study showed that an appropriate empirical relation could be generated for new and service exposed materials between both the techniques. Conventional test methods require large quantity of material removal for test samples from in-service components whereas small punch test method needs only a miniature sample extraction. This small punch test technique could also be extended to evaluate the thicker section boiler components such as pipelines and headers in the boiler as a part of remaining life assessment study. Also this technique could be a useful tool to any metallic component where large quantity of sample removal may be difficult or may not be feasible.

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Determination of creep property of 1.25Cr0.5Mo pearlitic steels by small punch test

Engineering Failure Analysis ◽

10.1016/j.engfailanal.2012.10.004 ◽

2013 ◽

Vol 28 ◽

pp. 215-221 ◽

Cited By ~ 35

Author(s):

Feng Hou ◽

Hong Xu ◽

Yucheng Wang ◽

Li Zhang

Keyword(s):

Creep Property ◽

Small Punch Test ◽

Small Punch ◽

Punch Test

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Determination of Material Fracture Toughness by Circular Pre-Cracked Small Punch Test Specimens

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.795.165 ◽

2019 ◽

Vol 795 ◽

pp. 165-171

Author(s):

Wu Lin Wang ◽

Du Wei Wang ◽

Kai Shu Guan

Keyword(s):

Fracture Toughness ◽

Empirical Correlation ◽

Fracture Toughness Test ◽

J Integral ◽

Small Punch Test ◽

Small Punch ◽

Punch Test ◽

Determination Procedure ◽

Material Fracture

Fracture toughness empirical correlation between SPT(Small Punch Test) with non-crack sample and standard fracture toughness test has been established in recent years. In order to compensate the imperfection of empirical correlation, such as absence theoretical basis, poor repeatability and universality, in this paper, an O-type pre-cracked sample was adopted to evaluate fracture toughness. The mechanical model of the sample is in compliance with plane strain condition in the direction of crack propagation. In this paper a determination procedure was studied and established, and the J-integral of steel Q345R was calculated using the procedure.

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