Control of cast irons by thermal analysis

摘要

Thermal analysis of cooling curves from the solidification of cast irons has been used as a foundry process control tool for nearly 50 years [1, 2]. Originally thermal analysis was intended to provide an indication of metal composition in the form of a "carbon equivalent liquidus value" for engineering grey (flake graphite FC) irons thus enabling process control without the need for an analytical laboratory. Carbon equivalent measurement provided a ready guide to the chilling characteristics and mechanical properties of the iron before it was poured into moulds. This paper provides a short review on how this "simple" test has been continually improved to provide much more information about the solidification behaviour of cast irons and so enable casting defects to be avoided in grey, ductile and compacted graphite irons. Recently thermal analysis has made a major contribution to the successful application of compacted graphite iron for modern diesel engine blocks.