Effect of composition on hot cracking susceptibility of Arc-Directed Energy Deposited microalloyed Al–Cu alloys

Abstract

Microalloying enhances the properties of Arc-Directed Energy Deposited (Arc-DED) Al–Cu alloys but influences the Hot Cracking Susceptibility (HCS). This study investigated the HCS of Cd and Ag–Mg microalloyed Al–Cu alloys during Arc-DED by both calculation and experiment. Solidification paths, accounting for solid-state diffusion, were calculated. From solidification paths, the index |dT/d(fs1/2)|max near fs = 1 was calculated to assess solidification cracking susceptibility. Circular-patch welding tests were conducted by Arc-DED single-wall samples. Results of Circular-patch welding tests indicate a strong correlation between total solidification crack length and |dT/d(fs1/2)|max, confirming the effectiveness of the index in Arc-DED. Results of calculation suggest Cu content exerts the most significant influence on HCS. Increasing Cu content reduces HCS by increasing eutectic content, while the effect of Cd content on HCS is less than 5 % when Cd content ranges from 0 to 0.3 wt%. Coupling effects among Cu, Mg, and Ag were observed. When Mg content is 0.3 wt% and content of Cu and Ag is high, HCS is approximately 1000 °C higher than that with other composition. Composition of micro-alloyed Al–Cu alloys with HCS comparable to 2319 alloy was proposed.

Keywords

• Chemical composition
• Arc-directed energy deposition
• Microalloyed Al–Cu alloys
• Hot cracking susceptibility