The sensitivity of the interface heat-transfer coefficient to pressure and fluid flow

• Published in: Metallurgical and materials transactions. B, Process metallurgy and materials processing science Vol. 32; no. 6; pp. 1213 - 1215
• Main Author: SEKHAR, J. A
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01.12.2001; Springer Nature B.V
• Subjects: Applied sciences; Exact sciences and technology; Fluid dynamics; Fluid flow; Heat transfer coefficients; Metallurgical fundamentals; Metals. Metallurgy; Production of metals; Theoretical study; Interface phenomena; Pressure effect; Heat transfer coefficient; Flow(fluid); Heat transfer
• ISSN: 1073-5615; 1543-1916
• DOI: 10.1007/s11663-001-0112-9

A small grain size distribution is a critical feature that controls the quality (reliability, fatigue strength, and hot cracking tendency) of net-shaped castings and cast sheets of aluminum, nickel, or ferrous alloys. In this respect, fluid flow often plays a large part in controlling the grain size either directly (momentum transfer to a weak evolving solidifying structure) or by directly influencing the composition and thermal gradients in the solidifying casting. Fluid flow has also been noted to influence the interface heat-transfer coefficient between the casting and its net-shaped mold because of the pressure applied to the mold wall interface (the pressure could arise, for example, because of flow). This last influence, although significant, has often been disregarded or underestimated in the literature. The aim of this article is to point to the evidence for the strong influence of flow on the interface heat-transfer coefficient. (Examples: aluminum alloys die cast and squeeze cast.)