The Effects of Rolling Process on the Microstructure and Properties of Columnar-grained Cu-12 wt.％Al Alloys

摘要

Cu-12 wt.％Al(Cu-12Al) alloy fabricated by continuous unidirectional solidification(CUS) process has high elasticity,high strength,high conductivity,high plasticity and other good comprehensive properties,which has a potential to develop into a high-performance elastic material as the alternative to beryllium bronze.Especially,the room temperature tensile elongation of the columnar-grained structure(CGS) Cu-12Al alloy with high 〈001〉β orientation along the axial direction exceeded 20％,which is six times more than that of the ordinary polycrystalline structure (OPS) Cu-12Al alloy(ε=2-4％) fabricated by traditional casting.The CGS Cu-12Al alloy shows lower flow stress and work-hardening rate during plastic deformation,which determines a dramatic improvement of workability comparing with the OPS alloy.In the present paper,both the effects of the rolling process and its parameters on the microstructure and properties of the CGS Cu-12Al alloy sheets were investigated.The results showed that the CGS sheets (σb=310 MPa,ε=19％) have the maximum reduction of 80％ and remain columnar-grained structure after the first rolling pass at 700°C.After deformation the tensile strength was 401 MPa and the tensile elongation approached to 14％.Then,the hot rolled sheets were rolled again through the second pass at 325°C and 700°C,respectively.The maximum reduction of CGS sheets at 325°C warm rolling was 20％,the sheets remain columnar-grained structure and β1'→α1' martensitic phase transformation occured; The second pass hot-rolling at 700°C showed that the maximum reduction exceeded 60％,and the recrystallization occured in the sheets.After two passes of hot-rolling (total deformation was 92％),although the recrystallization occured,the CGS sheets remained columnar-grained structure(CGS) high tensile elongation(8.3％),which is two times more than that of the as-cast OPS sheets,and is five times as much as the OPS sheets with the same total deformation.