SYMPOSIA PAPER Published: 01 January 1993

In-Situ Measurements of Mechanical Properties Using Novel Automated Ball Indentation System


Determination of the integrity of any metallic structure is required either to ensure that failure will not occur during the service life of the components (particularly following any weld repair) or to evaluate the lifetime extension of the structure. A portable/insitu stress-strain microprobe system was developed to evaluate nondestructively in situ the integrity of metallic components [including base metal, welds, and heat-affected zones (HAZs)]. The microprobe system utilizes an innovative automated ball indentation (ABI) technique to determine several key mechanical properties (yield strength, true-stress/trueplastic-strain curve, strain-hardening exponent, Lüders strain, elastic modulus, and an estimate of the local fracture toughness). This paper presents ABI test results from several metallic samples. The microprobe system was used successfully to nondestructively test in-situ a circumferentially welded Type 347 stainless steel pipe. Four V-blocks were used to mount the testing head of the microprobe system, allowing a 360° inspection of property gradients in the weld and its HAZ.

Author Information

Haggag, FM
Advanced Technology Corporation, Oak Ridge, TN
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Developed by Committee: E10
Pages: 27–44
DOI: 10.1520/STP12719S
ISBN-EB: 978-0-8031-5250-2
ISBN-13: 978-0-8031-1869-0