抄録
The mechanical properties of die-castings, the effects of casting conditions upon these, and the relation between the microstructure and the strength of the products have been studied. The results are summarized as follows.
1. The mechanical properties of the die-cast tensile specimens were sensitively affected by the casting temperature, but not by the die-temperature.
2. The injection pressure affects upon the mechanical properties. A sufficiently high pressure is needed for improving the strength.
3. The proof stress at 0.2 percent offset of the silumin die-cast tensile specimens lies almost within the range between 12 and 14kg/mm2, and was nearly constant regardress of the tensile strength when its strength was above 17kg/mm2.
4. The average elongation in 50mm of the above-mentioned specimens was 2.8% for the nominal tensile strength (24.5kg/mm2 of ASTM), which was lower than the nominal value.
5. The relation between the microstructure and the mechanical properties of the die-cast automobile parts were examined, but the difference of strength which depended on the micro-structures could not exactly be decided.
6. The roughness of surface of the die-casting and the die cavity was tested. It is considered from these tests that the roughness of surface of the davity is propertional to numbers of shot.
