Effect of machining process on stable crack growth

Abdel Hamid I. Mourad, Aladdin Abu-Assi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Citations (Scopus)


This paper aims to present an experimental evidence of the effect of machining process on stable crack growth behaviour (SCG) through AISI 4340 low alloy steel. Brittle fracture behaviour had been discovered in a batch of compact tension CT specimens, unlike previous batches that had shown ductile (stable crack growth) behaviour. This was unexpected, and indeed, was anomalous. An investigation was thus carried out to understand what processes that have affected the behaviour. Such anomalous brittle behaviour was observed while performing the fracture test on the affected specimen. The load-load displacement (P-ΔLL) curves show that the "normal" specimen exhibiting stable crack growth and the non-linear region, in the anomalous curve of the anomalous specimens, is rather limited. This indicates very limited, if any, stable crack growth. Fracture tests were carried out on CT specimens with different heat treatments to find the cause of this unexpected embrittlement. Micro-hardness measurements, tensile tests and microscopic (SEM) examination were also carried out and reported. The results suggest that, a great attention is needed during machining process to avoid accidental changes in the properties and to avoid misleading experimental results.

Original languageEnglish
Title of host publicationProceedings of the ASME Pressure Vessels and Piping Conference 2009 - Materials and Fabrication
Number of pages6
EditionPART A
Publication statusPublished - 2010
Event2009 ASME Pressure Vessels and Piping Conference - Prague, Czech Republic
Duration: Jul 26 2009Jul 30 2009

Publication series

NameAmerican Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP
NumberPART A
ISSN (Print)0277-027X


Other2009 ASME Pressure Vessels and Piping Conference
Country/TerritoryCzech Republic

ASJC Scopus subject areas

  • Mechanical Engineering


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