Fe-15Mn-10Cr-8Ni-4Si 制振ダンパー合金の鋳造組織と材料特性に及ぼす熱処理の影響

抄録

  A seismic damper alloy with a composition of Fe-15Mn-10Cr-8Ni-4Si and excellent plastic fatigue properties has been developed. Since this material was designed for thermomechanical processing, its properties as a cast material have not been investigated. In this study, sand and permanent mold castings were fabricated using this alloy, and the effects of heat treatment on the material properties were investigated. Heat treatment at 1000℃ for up to 24 hours was applied to investigate changes in microstructure and tensile and fatigue properties. As a result, both sand mold and permanent mold castings showed good tensile properties. The permanent mold castings showed good plastic fatigue properties at the heat treatment times of 2 to 8 hours, and the number of fracture cycles at a strain amplitude of ± 1% exceeded 10,000 cycles. Transformation from γ-austenite to ε-martensite was observed during plastic deformation, suggesting that this transformation contributes to the good plastic fatigue properties. In the cast microstructure, Mn, Ni and Si were observed to segregate clearly in the inter-dendrite region, suggesting that the remaining of segregation to some extent also contributes to good fatigue properties.