Conditions for the Formation of "A" Segregation and Precipitating Phases in iron-base superalloy A 286

Abstract

Iron-base superalloy A286 has been increasingly used for such application as components for power industry because of its high strength at high temperatures. In the ingot of this material, however, heterogeneities such as "A" segregation and Laves phase are easily formed to deteriorate the properties of the products.
In this study, therefore, an ESR ingot 1 000 mm in diameter was produced and examined in search for measures to reduce these heterogeneities. By beeing based on the result, laboratory experiments were carried out reproducing "A" segregation in a small ingot. The result revealed that lowering Si and Ti contents and making liquid pool angle smaller, which corresponded to shallow liquid pool in actual ESR ingot, were favorable for reducing "A" segregation. From another series of experiments it was made clear that lowering Si and Ti contents was also favorable for reducing Laves phase which tended to appear in micro-segregated interdendrite.