抄録
The dendrite-like structure in the annealed structure of steel castings, which is considered as an annealed structure and has no effect on the mechanical properties stated in the standards of the tensile test, has not been studied enough to be understood in detail. The authors have been finding such structures in parts of Y-block specimen. The present study to obtain a sufficiently homogeneous annealed structure and to understand the process of formation of such structures was carried out through the discussion on the changes in the annealing conditions by observation of the microstructure and analysis by the electron probe microanalyzer.
The dendrite-like structure in the annealed structure can be improved by elevating the annealing temperature or by repetition of annealing, which changes the structure into a considerably homogeneous one. The dendrite-like structure is formed due to insufficient diffusion of solute elements during solidification and unhomogeneous deposition of carbon, once diffused in austenite, with segregated elements during slow cooling after annealing. Such dendrite-like structure is an unhomogeneously annealed structure which resulted from heating and cooling under imperfectly thermal condition.
