Effect of post weld heat treatment on the 6061 aluminum alloy produced by ultrasonic additive manufacturing

Abstract

Ultrasonic additive manufacturing (UAM) is a solid-state additive manufacturing technique employing principles of ultrasonic welding coupled with mechanized tape layering to fabricate fully functional parts. However, parts fabricated using UAM often exhibit a reduction in strength levels when loaded normal to the welding interfaces (Z-direction). In this work, the effect of post-weld heat treatments (PWHT) on Al-6061 builds fabricated using the UAM process was explored aiming to improve the mechanical strength of the UAM builds. Tensile testing with digital image correlation (DIC) coupled with metallography along with multi-scale structure characterization (SEM-EBSD) was used to investigate and rationalize the mechanical performance of the UAM builds. It was established that PWHTs may improve the Z-strength level by the factor of ~33.5 (from ~46 MPa to 177 MPa). The improvements in the strength level were primarily aided by material aging and grain growth across the bond interface.

Power Ultrasonic Additive Manufacturing: Process Parameters, Microstructure, and Mechanical Properties

“…Parabolic defects are associated with the medium or medium-to-high weld density levels, while point defects were observed with specimens with very high weld density levels [5]. Similar observations have been reported on Al6061-H18 [13] and 4130 steel/steel parts [21].…”

“…With this attribute, bonding of dissimilar materials becomes feasible, and the properties of each building martial are retained. Similar and dissimilar builds via UAM such as Al-Al [10,[12][13][14][15], Al-Ti [16], Al-NiTi [17], Al-SiC [18,19], Al with embedded dielectric materials (inks used in printed electronics industry) [20], low carbon steel [21,22], and Alshape memory alloy (SMA) [23] have been reported in the literature so far.…”

Microstructure, thermo-mechanical properties and Portevin-Le Chatelier effect in metastable β Ti-xMo alloys

“…Furthermore, Niu et al [44] studied the effects of temperature and strain rate on serration type in Al 0.5 CoCrFeNi high entropy alloy, and results showed that serration type transforms from A to A+B and then to B+C when increasing temperature and decreasing strain rate. Concerning the spatial aspect, bands of localized deformation (PLC bands), associated to the jerky flow, are generally classified as type A-continuous propagation [45], type B-hopping propagation [46] and type C-random nucleation [47]. The band propagation is usually observed by four methods including digital image correlation (DIC) [48], digital speckle pattern interferometry [49], infrared thermography [50] and shadowgraph [51].…”

Probabilistic Evaluation of Fatigue Crack Growth Rate for Longitudinal Tungsten Inert Gas Welded Al 6013-T4 Under Various PostWeld Heat Treatment Conditions

“…may fall on a degradation [4,6,7]. It has been reported that those mechanical properties of the welded material can be improved by applying a post-weld heat treatment (PWHT) for a particular period and temperature [8,9].…”