Published: Jan 1993
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A number of issues and problems were encountered in the course of installing an automated tension testing machine and linking it to a Laboratory Information Management System (LIMS).
Difficulty was encountered in having software written to correctly calculate certain mechanical properties of steels, for which no rigorous mathematical definitions have been standardized. Additionally, it was difficult for equipment supplier and end-user to agree on how to analyze stress-strain curves having features not addressed by existing ASTM standards.
Interlaboratory comparison studies conducted with other labs in the steel industry to verify the results of the automated test machine revealed that labs are collecting data over significantly different strain ranges for their automated determinations of n values. As a result, n values do not compare well from lab to lab.
Also discussed are other details of the automation project, benefits that have been realized, and some of the laboratory's plans for the future.
It is concluded that ASTM standards require significant revision to support automated testing—not only to address the many issues that are being brought to light by automation, but also to specify automated procedures for the determination of mechanical properties.
automation, mechanical testing, yield point (YP), yield point elongation (YPE), yield strength, tensile strength, strain-hardening exponent, Laboratory Information Management System (LIMS)
Quality engineer, Armco Steel Co., L. P., Middletown Works Met Lab, Middletown, OH