Numerical simulation of solidification of various orthogonal junctions of cast iron plates of a uniform thickness, such as L, T or X junctions. revealed that the solidification time is roughly proportional to the square of the inscribed circle diameter as reported by Wlodawer, though some exceptional deviations from this rule which had not been recognized before were also found. Effects of fillet radius on the solidification time were determined, verifying that Wlodawer’s results were qualitatively correct, but not quite quantitatively. Some corrective measures were proposed in using the inscribed method or the modulus method for estimating the solidification time of the junctions.

抄録全体を表示

  Austempered ductile cast iron (ADI) is expected to be applicable to many parts due to its high tensile strength and high hardness. ADI, however, is also known to be an extremely hard to machine material. The present investigation therefore aimed to improve the drilling efficiency of ADI. The cutting performance of (Ti, Al) N coated cemented carbide tool in drilling was investigated. The results clarified that the tool life of (Ti, Al) N coated cemented carbide drills at a cutting speed of 1.00 m/s was better compared to cemented carbide drills at the usual cutting speed of 0.50 m/s. With the (Ti, Al) N coated cemented carbide drill, no damage of the cutting edge was observed at the cutting speed of 1.00m/s, and excellent degree of roughness of the machined surface was obtained. Though the wear resistance slightly improved in mist machining, tool life was determined by damage.

抄録全体を表示

  It is useful to bond components with different materials on the surface of castings by the cast-in insertion process. The process is called “end-surface cast-in bonding”. To examine the capabilities of this process in practical applications, experiments to bond mild steel rings to the surfaces of ductile iron castings were performed. Solidification analysis was also carried out to clarify thermal conditions at the interface.
  Experiments showed that in end-surface bonding, volume ratio larger than 30 is necessary for good metallurgical bonding. The value is much larger than the values in usual buried insertion where inserts are almost wholly inside the castings. Thermal spraying of Ni-base alloy on the surface of the inserts enhanccd bonding, and enabled bonding at the volume ratio of 5. Thermal analysis revealed that solidification of melt at the bonding interface in end-surface bonding is faster than the buried insertions with the same volume ratio. This is because the contact area of insert and mold in end-surface bonding is larger while the contact area of insert and melt is smallcr than that in the buried insertion.

抄録全体を表示

  Metallographic and fractographic studies of aluminum casting show that oxides are frequently observed in the neighborhood of porosity defects. It has been proposed that the entrapped oxides in the collision of melt surface during mold filling become nucleation sites of porosity. In this work, we proposed a new method that can simulate oxides entrapment during mold-filling process, and final size and distribution of the oxides after the mold filling. In this model, the oxides are represented by marker particles and the velocity of markers is calculated in a similar way to the Marker and Cell method. It was found that this algorithm can predict the distribution of porosity that could not be predicted by conventional methods.

抄録全体を表示

  Using CaO refractories, vacuum induction melting is increasingly applied to Fe-Si-Al alloys for magnetic recording materials. However, as Si and Al contained in Fe-Si-Al alloys are reactive with CaO, it is important to consider the effects of these elements on refining properties in the melting process.
  In this work, experiments were performed to examine the effects of the adding order of these elements on the refining characteristics in the melting process. It was found that the cleanest Fe-Si-Al alloy can be obtained by adding a small amount of Al first and then Si and the Al remaining. This effect can be explained by the reactions between the wall of CaO and Al and Si.

抄録全体を表示

  A practical method has been proposed to predict temperature change, and graphite and austenite volume as the initial step for predicting porosity defect in spheroidal graphite (SG) cast iron. The nucleation of spheroidal graphite was assumed to be one step nucleation and the nucleation temperature was calculated from an experimentally determined relationship between the cooling rate at the eutectic temperature and undercooling. The graphite grain density was calculated from an experimentally determined relationship between the undercooling and graphite grain density. The graphite growth was assumed to be controlled by the carbon diffusion through the austenite shell around the graphite nodule. The simulated cooling curves, and graphite grain density and volume agreed rather well with observed ones while CPU increase was only about 20%, showing this method is practical. Furthermore, the porosity formation mechanism in SG cast iron castings was studied by deformation analysis using the VOXEL method.

抄録全体を表示

  A thermoelectric device, that is a thermoelectric brick into which Bi-Te thermoelectric modules were incorporated, was prepared to convert the waste heat from founding processes into electric energy. It was applied to a casting process for manufacturing BC6 copper alloy products. A stainless vat filled with green sand taken out from the mold just after casting was placed on the thermoelectric brick. Electrical voltage generated in the brick was measured to be 1.2V at maximam when the temperature difference ⊿T between Cu plate located on the top of the brick and the edge of the cooling fin was 10K. To obtain larger ⊿T, the thermoelectric brick was brought into direct contact with the casting mold. In this case, an electrical power of 0.23W was obtained with larger ⊿T above 50K when the external resistance of 10Ω was applied in the circuit. It was clarified that direct contact of thermoelectric brick with the mold and application of the external resistance equal to the internal resistance of thermoelectric modules led to more effective generation of electrical power.

抄録全体を表示