Estimation method of bonding state in composite casting with different material insertions

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Composite casting is a convenient way of making high performance castings by bonding different insert materials utilizing productivity of casting process. This study is to find a method to predict the bonding state, bond or no bond, from the geometrical and temperature data of the insert and the casting. The study consists of three steps ;(1)insertion experiment to bond mild steel disks or rings to the end face of a cylindrical cast iron castings, and the solidification analysis of the melt,(2)simulations of pipe and bar insertions with various dimension combinations, and(3)total examination of the bonding state with geometrical data from the simulations and the experiments. The results are as follows :(1) Necessary thermal condition for metallurgical bonding was established, wet contact of liquid melt with the insert longer than 100 s both in buried insertion and end face bonding.(2) Necessary volume ratio, VR, to achieve the condition is 8-10 for pipe and bar insertions and about 30 … More in end face bonding.(3) However, the critical VR depends on the thickness of the inserts, the similarity with VR is not vaild.(4) Bond or no bond can be expressed by the areas in a t (insert thickness) - 1/VR diagram, the approximate border lines were indicated.(5) The diagram are divided into three zones, (I)small insert zone where bonding state is determined by the volume of the casting, (II)intermediate zone where necessary volume ratio is almost constant and the minimum, and (III) large insert zone where the bonding is determined by the insert thickness.(6) Unified judging diagram for pipe and bar insertions and end face bonding may be possible by some conversion parameters.Another results of the stydy are ;(7) data of appropriate range of material constants and boundary parameters for simulation were obtained,(8) mechanism and the thermal conditions of melting of steel inserts in cast iron melt was clarified, and(9) mechanism of bonding WC-Co insert with cast iron was also revealed. Less