SKD11工具鋼の高温変形挙動に及ぼす加工熱処理の影響

抄録

The effects of thermomechanical treatments (TMT;warm working and ausforming) on the high temperature deformation behaviors of high carbon and high chromium steels (SKD11 die steels with 1.5%C-12%Cr) are investigated. Thermomechanically treated steels yield very fine ferrite grains of 0.3 to 0.6μm. When tensile tested just below the Ac₁ temperature, the elongation of non-thermomechanically treated material is 130%, whereas, the ausformed material shows 320% elongation. The raise in ductility indicates the beneficial effect of TMT due to the refinement of microstructure. Image analysis on the grain-elongation during deformation of the materials shows that the degree of grain-elongation along the tensile axis in the finer grained material is smaller. This means that in the relatively finer grained materials, the contribution of the grain-elongation to the deformation of the materials is smaller but the contribution of grain boundary sliding is larger, compared to that of deformation of coarse grain materials.