High Strength Ductile Iron Produced by Engineered Cooling: Process Concept

Abstract

Traditionally, high strength ductile irons are produced by a combination of alloying and heat treatment, both operations substantially increase the cost and carbon footprint of casting production. In this study, the concept of a process for the production of high strength ductile iron using engineered cooling is discussed. The process includes early shakeout of the casting from the mold and application of a specially designed cooling schedule (engineered cooling) to develop the desired structure. The high extraction rate of internal heat is achieved by controlling the thermal gradient in the casting wall and the surface temperature. Experimental “Thermal Simulator” techniques and Computational Fluid Dynamic (CFD) simulations were used to design the cooling parameters. The concept was experimentally verified by pouring plate castings with 1” wall thickness and applying the engineered cooling techniques. The tensile strengths of ductile iron increased from 550–600 MPa for castings solidified in the mold to 1000–1050 MPa after engineered cooling.