Microstructure and mechanical property evolutions of CuNi10Fe1.8Mn1 alloy tube produced by HCCM horizontal continuous casting during drawing and its deformation mechanism

Abstract

Heating-cooling combined mold (HCCM) horizontal continuous casting was used to produce Ф70 mm × 3.5 mm CuNi10Fe1.8Mn1 alloy tubes. The as-cast tube had good surface quality, strong axial columnar grains and high elongation to failure of 45%, and can be directly drawn without surface treatment. The maximum cumulative cold deformation amount reached 94%. For the small deformation amount (<46%), dislocation sliding was main deformation mechanism, numerous dislocation cells formed and microregion crystal rotation in grains happened. When the deformation amount was 76%, shear deformation extent increased and many parallel shear bands formed in gains. With increasing the deformation amount to 92%, a large number of shear bands in different directions formed and the intersecting of shear bands induced displacement of 100–200 nm themselves, which formed wave-shaped deformation structures. With increasing the deformation amount, the tensile strength and hardness of the tube increased from 235 MPa and 86 HV of the as-cast tube to 585 MPa and 168 HV of 94% deformation amount, but the elongation to failure reduced to 6.6%. The process of HCCM horizontal continuous casting→drawing can work as a new compact method to produce thin-walled cupronickel alloy tube.