Effect of Cr Dopant on High-Temperature Embrittlement in Fe Alloys Containing High Concentration of Cu

概要

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To evaluate usage of ferrous scraps containing a high concentration of Cu, the mechanical properties of Fe–Cu alloys with 0.3∼4.0 mass% Cu were examined focusing on the effect of the Cu-rich phase segregated at grain boundaries on high-temperature embrittlement; ductility improvement was attempted by adding a small amount of Cr. Excess Cu atoms in the Fe–Cu alloys segregated and formed Cu-rich phase at the grain boundary in α matrix depending on the grain boundary character. Large Cu-rich phase was susceptible to nucleation of microcracks and induced grain boundary fracture, resulting in a loss of ductility at high temperature. Addition of a small amount of Cr effectively improved ductility of α Fe–Cu alloys at high temperature because the formation of Cu-rich phase was suppressed by Cr addition and/or segregated Cr increased the bonding force at grain boundaries. Ductility decreased in γ Fe–Cu alloys with increasing Cu concentration and this reduction was not improved by Cr addition. High strength Fe–Cu alloys containing a large quantity of Cu was obtained, however, by Cr addition.
社団法人日本鉄鋼協会の論文
1998-08-15