Statistical distributions of fracture strengths of cast Al7SiMg alloy

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 1993-12, Vol.173 (1), p.261-266
• Main Authors: Green, N.R., Campbell, J.
• Format: Article
• Language: English
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fatigue, corrosion fatigue, embrittlement, cracking, fracture and failure; Fatigue, embrittlement, and fracture; Materials science; Metals. Metallurgy; Physics; Treatment of materials and its effects on microstructure and properties
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/0921-5093(93)90226-5

Al7SiMg alloy vertically cast test bars were produced in dry sand moulds by top filling (TF), turbulent bottom filling (TBF) and turbulence-free bottom filling (TFBF) with filtered metal. The test bars were heat treated prior to tensile testing. Scanning electron microscopy examination of polished sections showed that all the test bars contained tangled networks of oxide films which are seen to constitute cracks within the metal. They are more prevalent in the TF and TBF castings. A large number of anomalous features are observed on all fracture surfaces. These are oxide films produced during filling and entrained in the casting. The best description of the skewed distributions of tensile strengths of each set of castings was obtained with the Weibull distribution. Weibull slopes of 11, 20 and 38 were obtained for the TF, TBF and TFBF castings respectively.