TY - GEN
T1 - Effect of machining process on stable crack growth
AU - Mourad, Abdel Hamid I.
AU - Abu-Assi, Aladdin
PY - 2010
Y1 - 2010
N2 - 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.
AB - 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.
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U2 - 10.1115/PVP2009-78085
DO - 10.1115/PVP2009-78085
M3 - Conference contribution
AN - SCOPUS:77952995977
SN - 9780791843697
T3 - American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP
SP - 197
EP - 202
BT - Proceedings of the ASME Pressure Vessels and Piping Conference 2009 - Materials and Fabrication
T2 - 2009 ASME Pressure Vessels and Piping Conference
Y2 - 26 July 2009 through 30 July 2009
ER -