Effect of Solidification Conditions on the Deformation Behavior of Pure Copper Castings

Abstract

The effect of solidification conditions on the tensile deformation behavior of pure copper castings for electrical parts was investigated. Two main types of tensile deformation properties were distinguished on the basis of the difference in uniform elongation. For the castings fabricated under a superheat of 100°C or 150°C, larger and smaller uniform elongation types corresponded to the absence and presence, respectively, of the CuCu 2 O eutectic phase in the microstructure. Meanwhile, for the castings fabricated under a superheat of 50°C, greater uniform elongation was sometimes obtained when the eutectic phase was present. In addition, irrespective of the presence or absence of the eutectic phase, greater uniform elongation was always obtained when chills were used. Cross-sectional observations showed the existence of considerable nonspherical porosity when the eutectic phase was present; the porosity was reduced when the pouring was conducted under the superheat of 50°C and when the chills were used because of lower hydrogen content in the melt and supersaturation of the hydrogen by rapid cooling, respectively. These results suggest that not only the presence of the eutectic phase but also the inferior casting soundness due to the existence of the porosity is a dominant factor responsible for the decrease in the uniform elongation. The findings presented here indicate that a decrease in the hydrogen content in the melt and/or the rapid cooling during solidification are effective measures to stably achieve practically sufficient deformation properties along with superior casting soundness.

Prediction of Periodic Centerline Porosity and Pulse Marks by CFD and Experimentation for Continuously Cast Copper

“…For setting c, the curve displayed typical behavior for VUCC 8 mm OFCu, which was a ductile sample indicated by the reduction in stress prior to fracture point, and produced an average ultimate tensile strength (UTS) of 160 ± 21 MPa and fracture point of 33 ± 3 pct, which were within the minimum industrial standard for electrical pure copper casting (155 MPa and 35 pct, for JIS H 5120 CAC102). [29] The results also matched properties for upwards cast OFCu in. [30] Without the presence of defects, setting c, the UTS along with the fracture point increased.…”

“…The porosity formed within had spherical/ellipsoid structures with some uniformity and regular shape. This type of porosity is observed in pure metal casting such as OFCu and with Cu-Cr alloys due to volume shrinkage and insufficient liquid metal replenishment, [29,38] with this affect discussed in more details in Section III-D. For a comparison with a defect-free rod, CT images of setting c are shown in supplemental Figure S5 and highlighted a dense uniform structure and a grain structure typical for OFCu: equiaxed smaller grains at the outer edge with larger columnar grains oriented toward the center axis. [1] Further analysis of the pore's position and form was obtained by CT scans of rods which had not been altered in any form after casting (stress tested or chemically etched), for all speed settings.…”

Recent Development of Joining and Conductive Materials for Electronic Components

“…In conventional manufacturing processes, solidification conditions' effect on pure Cu castings was investigated, and because of the solidification conditions affecting the microstructure, it was shown that the deformation behavior was affected. 127) Grain refinement using ultrasonic radiation during the casting of high-purity Al has been reported. 128) Recently, ultrafine-grained structures produced by accumulative roll bonding (ARB) have attracted attention for improving material properties such as the ultimate tensile strength of processed high-purity Al, which increased 35 times compared with that of coarsegrained Al.…”