Macrostructure and properties of thin walled copper tubes prepared by the downward continuous unidirectional solidification method

The macrostructure and properties of the thin walled copper tube prepared by the downward continuous unidirectional solidification （DCUS） method were studied. The result shows that the macrostructure is closely related to the solid-liquid interface profile, which is influenced by the distance between the cooling water location and the solidification front. The mechanical properties of the thin walled copper tube prepared by the DCUS method are near those of the normal cast copper, and it has good relative density, electrical conductivity, and elongation, which are not greatly affected by casting speed. The thin walled copper tube prepared by the DCUS method also has good processing properties that can be taken to further drawing procedures directly without an intermediate process, and obtains good mechanical properties with the total processing rate of 89.8%.

Microstructure and mechanical properties of Al-Mg-Si alloy fabricated by a short process based on sub-rapid solidification

Al-Mg-Si(AA6xxx)series alloys have been used widely in automotive industry for lightweight purpose.This work focuses on developing a short process for manufacturing Al-0.5Mg-1.3Si(wt.%)alloy sheets with good mechanical properties.Hereinto,a preparation route without homogenization was proposed on the basis of sub-rapid solidification(SRS)technique.The sample under SRS has fine microstructure and higher average partition coefficients of solute atoms,leading to weaker microsegregation owing to the higher cooling rate(160℃/s)than conventional solidification(CS,30℃/s).Besides,Mg atoms tend to be trapped in Al matrix under SRS,inducing suppression of Mg2Si,and promoting generation of Al Fe Si phase.After being solution heat treated(T4 state),samples following the SRS route have lower yield strength compared with that by CS route,indicating better formability in SRS sample.After undergoing pre-strain and artificial aging(T6 state),the SRS samples have comparable yield strength to CS samples,satisfying the service requirements.This work provides technological support to industrially manufacture high performance AA6xxx series alloys with competitive advantage by a novel,short and low-cost process,and open a door for the further development of twin-roll casting based on SRS technique in industries.