Suitability of Miniature Tensile Specimens for Estimating the Mechanical Property Data of Pressure Tubes: An Assessment

Balakrishnan, K.S.; Samal, M. K.; Parashar, Jalaj; Tiwari, G.P.; Anatharaman, S.

doi:10.1007/s12666-013-0316-0

Cited by 7 publications

(3 citation statements)

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“…Notably, B and A from reference [20] were not explicitly mentioned, but obtained from communication with the principal investigator of the test program. Studies [7,10,11,13] show good agreement between the tensile test data acquired with these dimensions and tensile test data of full size specimens, both machined out of the same homogeneous material.…”

Section: Tensile Testing Of Miniature Specimensmentioning

confidence: 65%

“…This is typically associated with a width W of the reduced section of about 2 mm [1,[5][6][7][8][9][10][11][12][13]. As seen in Figure 2, which compares the result of such a miniature tensile test (cross section of the reduced section: 2 mm x 0.5 mm) of a homogeneous material to a standard sized tensile test of the same material, there are clear but reasonable deviations in the stress-strain curve.…”

Section: 2mentioning

confidence: 99%

“…The most common method used to produce miniature tensile specimens is wire electro discharge machining ('wire EDM') [1,7,8,10,11,[13][14][15][16][17] (note that one study used water jet cutting [18]). The advantage of EDM over traditional machining processes is that it can produce the small work piece accurately and to close tolerances with very little wasted material.…”

Section: Tensile Testing Of Miniature Specimensmentioning

confidence: 99%

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Characterisation of weld heterogeneity through hardness mapping and miniature tensile testing

Bally

Waele

Verleysen

et al. 2015

SCAD

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Abstract:Welding is a widely adopted industrial process used for joining components. A fusion weld has a highly heterogeneous microstructure and characterisation of strength heterogeneity is difficult because of the potentially large variations over a limited distance. Hardness mapping and miniature tensile tests are two distinct approaches to this problem. This paper reports on the possibilities and limitations of both techniques. Hardness mapping is a well-documented procedure as opposed to miniature tensile testing, where the dimensions of the dogbone shaped specimens are smaller than what standards prescribe. A particular challenge is the measurement of strains in such small specimens. The authors have achieved this measurement by means of Digital Image Correlation (DIC). To that end, a sufficiently fine speckling method has been developed.Keywords: heterogeneity; hardness mapping; miniature tensile testing; DIC INTRODUCTIONWelding is one of the most common joining methods due to its generally high production speed and low associated costs. It is often associated with flexibility, integrity and reliability [1]. An example application showing the economic importance of welding is pipeline installation. Costs associated to fusion welding are estimated to make up 20% of the total cost of pipe laying. These include aligning the pipe sections, cleaning and grinding, welding, checking the weld for flaws and coating the weld [2].Notwithstanding the economical appeal of welding, the localized application of heat and melting results in a high susceptibility to material discontinuities, flaws and residual stresses, whose presence may lead to structural failure and lifetime reduction. The prediction of weld flaw acceptability ('structural integrity') is hampered by the potential presence of strongly heterogeneous microstructures. Modern day weld flaw assessment ignores this heterogeneity by assuming a homogeneous weld. As such, a generally accepted method to characterise weld heterogeneity does not yet exist. STATE OF THE ARTHeterogeneity is inherent to fusion welds, because in order to melt the weld metal and fuse it with the base metal, heat has to be locally applied. For thicker sections, weldments are created in several passes (deposition of multiple layers), resulting in a variety of zones undergoing a succession of particular heat cycles. The heat cycle determines what the microstructure transforms into, each structure having a different stress-strain response. Not only the weld metal is heterogeneous due to this, but the heat affected zone (HAZ) of the base metal (heated but non-melted metal in close vicinity of the weld) also transforms.Many conventional steel welds show a hardened HAZ due to the occurrence of stronger microstructures. In contrast, a broad range of high strength low alloy steels obtain their properties from a fine grain size, resulting from a specific heat treatment, often combined with mechanical deformation. These steels may show a softened HAZ due to grain coarsening. To quantify variations ...

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