纳米改性Al-Zn-Mg-Cu合金电弧熔丝增材成形工艺及组织和性能

Formability,microstructure and mechanical properties of nano-treated Al-Zn-Mg-Cu alloy fabricated by wire arc additive manufacturing

采用电弧熔丝增材制造技术(WAAM)对纳米改性Al-Zn-Mg-Cu合金进行成形试验,分析了焊接电流、焊接速度、沉积路径、层间等待时间对成形性能的影响.结果表明,在焊接电流190 A、焊接速度350 mm/min、往复沉积、层间等待时间为90 s时合金具有良好的成形性能.对制备的直壁墙体进行了沉积后热处理,对不同状态合金的组织和性能进行了研究.沉积态及热处理态合金显微组织均具有优异的各向同性,由细小的、无明显取向的等轴晶组成.T6处理显著提高了沉积态合金的硬度及力学性能,T6处理后平均硬度为178.3 HV,较沉积态提升61%,沿横向抗拉强度(Rm)、屈服强度(R_(eL))与断后伸长率(A)分别为469.7(±5.1)MPa,366.3(±1.4)MPa与6.4(±0.4)%,沿纵向抗拉强度(Rm)、屈服强度(R_(eL))与断后伸长率(A)分别为454.3(±18.8)MPa,364.7(±16.7)MPa与5.9(±0.5)%,具有良好的力学性能各向同性.

Wire arc additive manufacturing(WAAM)was utilized to fabricate the nano-treated Al-Zn-Mg-Cu alloy.Effects of fabrication parameters on WAAM formability are systematically investigated.The results show that the nano-treated Al-Zn-Mg-Cu alloy is well formed by alternative path under the following parameters:welding current 190 A,welding speed 350 mm/min,dwell time 90 s.Post-deposition heat treatment is employed to further modify the microstructure and the mechanical performance.The WAAMed Al-Zn-Mg-Cu alloys at both as-deposited and heat-treated states exhibit homogeneous microstructure composed of fine equiaxed grains without preferred orientation.T6 heat treatment significantly improves the microhardness and mechanical properties of the as-deposited alloy.The microhardness of the T6 treated alloy reaches 178.3 HV,which is 61%higher than that of the as-deposited sample.The ultimate tensile strength,yield strength,elongation of the T6 treated alloy along horizontal and vertical directions are 469.7(±5.1)MPa,366.3(±1.4)MPa,6.4(±0.4)%and 454.3(±18.8)MPa,364.7(±16.7)MPa,5.9(±0.5)%respectively,demonstrating that the WAAMed nano-treated Al-Zn-Mg-Cu alloy has excellent mechanical isotropy.