CHARACTERISTICS OF EMBRITTLEMENT IN STEELS ABOVE 600 degree C.

Abstract

There exist three temperature regions where embrittlement is noticed: T//m similar 1200 (I), 1200 similar 900 (II), and similar 700 degree C (III). The cause in region I is a residual liquid film along dendritic interfaces. In region II, the precipitation of finely distributed oxy-sulfides at the austenite grain boundary weakens boundary strength, thus overaging such as slow cooling, holding, or slow straining result in good ductility. Embrittlement in III is manifest by the slower strain rate. Controlling factors are precipitation of oxides, sulfides and nitrides, precipitation of proeutectoid ferrite film along austenite grain boundary as well as grain boundary sliding.