Effects of Cu and Other Tramp Elements on Steel Properties. Influence of Cu and Sn on Hot Ductility of Steels with Various C Content.

The influence of Cu and Sn on the hot ductility at the strain rate of 10-3 s-1 for steels with C contents from 0.002 to 0.15 mass% was investigated. The hot ductility dropped at austenite+ferrite two phase region just below A3, namely, 800 to 900°C. The hot ductility deteriorated more at higher C content, and furthermore with the co-addition of Cu and/or Sn. It was considered that the deterioration at austenite+ferrite two phase region in the Cu, Sn bearing steel was caused by the combined effect of following factors: (1) the formation of proeutectoid ferrite along the austenite grain boundaries, (2) the segregation of Sn at the interface between proeutectoid ferrite and austenite or at the austenite grain boundaries, and (3) the increase in the difference of the deformation strength between austenite and proeutectoid ferrite.