Effect of Friction Stir Processing on Fatigue Behavior of an Investment Cast Al-7Si-0.6 Mg Alloy

Journal Article · Mon Feb 01 04:00:00 EST 2010 · Acta materialia, 58(3):989-1003

DOI:https://doi.org/10.1016/j.actamat.2009.10.015· OSTI ID:972938

Jana, Saumyadeep; Mishra, Rajiv S; Baumann, John B; Grant, Glenn J

Cast aluminum alloys in general show poor fatigue performance due to presence of defects. Friction stir processing (FSP) can be used as a tool for enhancing mechanical properties of cast alloys by eliminating such defects. In the present study FSP led to a five times improvement in fatigue life of an investment cast Al-7Si-0.6Mg hypoeutectic alloy. The reason for such enhancement was linked to closure of casting porosity which acted as crack nucleation sites in the as-cast condition. Porosity acted as notches in the as-cast alloy and led to an order of magnitude higher crack growth rate. As FSP eliminated the porosity and refined Si particles, crack growth rate dropped due to the elimination of the notch effect together with increased crack path tortuosity. Finally, short crack behavior was noted in both cast and FSP specimens. The critical crack length where transition from short crack to long crack behavior took place is related to respective microstructural characteristic dimensions.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 972938
• Report Number(s): PNNL-SA-68048; VT0504000
• Journal Information: Acta materialia, 58(3):989-1003, Journal Name: Acta materialia, 58(3):989-1003 Journal Issue: 3 Vol. 58; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALLOYS
ALUMINIUM
CASTING
CLOSURES
CRACK PROPAGATION
Cast Aluminum Alloy
DEFECTS
DIMENSIONS
FRICTION
FSW
Fatigue
Friction Stir Welding
MECHANICAL PROPERTIES
NUCLEATION
PERFORMANCE
POROSITY
PROCESSING