Abstract
This study was conducted to confirm the effects of metal flowlne on the strength of die castings, which has been considered to be strong in the direction parallel to the flowline and weak in the direction normal to that.
As the results of analysis of variance, the effects of metal flowline on the directional dependence of strength were not observed in Al-si-Cu alloy(JIS ADC12)die castings produced by mass production method.
The cause of the above facts was examined and the following results were obtained.
(1) The metal flowline patterns resulted from the difference in the solidification structure. Bright parts were rich in primary α-crystals and drak parts were rich in eutecic silicon. Its thickness ranged from several μ to 50 μ.
(2) Preferred orientation of crystals was not observed on the surface having metal flowline patterns;nor was in the inner parts. The degree of orientation was found to be random.
(3) Therefore, the anisotropy of strength was studied by orienting the α-phase in the heat flow direction by unidirectional solidification of the alloy;but it was not found even under such conditions.
(4) The strength of die castings depended upon porosity and conditions for cooling of dies. Therefore, it was concluded that the effects of metal flowline on the directional dependence of strength are out of the question.
