师昌绪系列讲座

Topic：Fluid and Semi-Solid Flow in Casting Processes

Speaker：Prof. Merton C. Flemings

                 Massachusetts Institute of Technology (MIT)

Time: 10:00-12:00 AM., Wed., Oct. 9^th, 2013

Venue: Room 403, Shichangxu Building, IMR CAS

Welcome to attend!

Abstract:

The engineering science of fluid and semi-solid flow has been critical to our modern understanding of casting processes, including macrosegregation, grain formation, hot tearing and semi-solid forming, as well as to the ancient process of puddling. We have come to understand how interdendritic flow leads to ingot macrosegregation and how bulk liquid convection leads to grain refinement. We are learning how dendritic grain structure affects semi-solid behavior under strain, and how that behavior affects hot tearing, shrinkage and segregation. Homogeneous thixotropic semi-solid flow is obtained in modern semi-solid forming by achieving a non-dendritic, fine grained structure. An ancient process that employed semi-solid flow is puddling (chao*). It was developed and employed in China in the early period of the Western Han dynasty (206 BC-24 AD) and re-discovered in the West only at the end of the 18th century. It remained an important process for producing wrought iron in both China and the West into the early 20th century. It is a quite interesting process when looked at through modern eyes; it demonstrated remarkable craftsmanship in the absence of the solidification understanding we have today.