论文部分内容阅读
In the present work,Zn-10Al-2Cu-0.05Ti (ZA10) alloy tubes with a diameter of 12.5 mm and wall thickness of 1.2 mm were fabricated by one-pass and double-pass Conform continuous extrusion.A stabilizing heat treatment[350 ℃,30 min (furnace cooling) + 120 ℃,12 h (air cooling)]was also applied to some of the double-pass tubes to improve the quality of their weld seams.The yield strength,ultimate tensile strength,elongation and expansion ratio of the one-pass continuous extrusion tube were 268.4 MPa,294.3 MPa,13.8％ and 5.5％,respectively.Double-pass continuous extrusion improved these values to 278.4 MPa,317.2 MPa,15.4％ and 11.4％,respectively.Double-pass tubes also had fewer aggregations of Al-α precipitates along the welding seam,which improved seam quality and caused cracks to appear in the matrix,away from the weld-affected zone,during expansion testing.Heat-treated double-pass tubes exhibited superior yield strength (283.9 MPa) and ultimate tensile strength (328.5 MPa) but lower elongation (10.2％)and expansion ratios (10.3％).Additionally,the heat-treated tubes exhibited markedly lower elongation at room temperature due to the remarkable blockage of dislocation motions by fine-scale lamellar (α + η) eutectoid structures and a lower size effect when stretched.