Solidification Cracking Restraining Mechanism of Al-Cu-Mg-Zn Alloy Welds Using Cold Metal Transfer Technique

Abstract

Aluminum alloy 7075 (with 7055 and 7150 filler wires) was welded using a digital welding machine that can switch arc mode between MIG, CMT and CMT+P modes. The transverse-motion weldability test of joints welded under different arc modes showed that the solidification cracking susceptibility was lower in CMT-technique-based welds than in MIG welds. The temperature cycle of the welding pool under different arc modes was recorded using mini-thermocouples, which showed that the cooling rate was lower in CMT welded samples than in MIG welded samples. The low cooling rate promoted the growth of α-Al dendrites through the back diffusion effect. Electron probe micro-analysis showed that micro-segregation of the α-Al dendrites was lower in the CMT welded samples than in the MIG welded samples. The T-(fAl)1/2 curve of each weld was calculated, which showed that CMT-based welding enhanced the bridging of adjacent α-Al dendrites, reducing the tendency for solidification cracking.

Modeling of Impurities Evaporation Reaction Order in Aluminum Alloys by the Parametric Fitting of the Logistic Function

“…The properties of the aluminum alloys are well examined topics where Cd, Hg, and Pb are often noted as the most unwanted metallic elements [3,4]. In recent years, with the advances in additive manufacturing, Zn is used in aerospace and defense industries to improve the corrosion resistance of aluminum alloys [5], although Zn is traditionally considered an impurity element due to the ease of microsegregation [6]. The presence of these elements causes a lower reliability of the solidification process and a reduction in mechanical properties in final products [7].…”

Effect of Brazing Temperature on Microstructure, Tensile Strength, and Oxide Film-Breaking Synergy of 5A06 Aluminum Alloy Welded by TG-TLP

“…It's important to note that aluminum alloy conduits and bar materials play a critical role in spacecraft manufacturing, including carrier rockets, manned spacecraft, and space stations. The connection of these materials is crucial for ensuring the safe operation of spacecraft [2][3][4]. However, the current method of manufacturing these conduits, tungsten argon arc welding (TIG), could have defects such as pores, unstable quality, and low qualified rate [5].…”