Fabrication of crack-free aluminum alloy 6061 parts using laser foil printing process

Abstract

Purpose This paper aims to present the fabrication of 6061 aluminum alloy (AA6061) using a promising laser additive manufacturing process, called the laser-foil-printing (LFP) process. The process window of AA6061 in LFP was established to optimize process parameters for the fabrication of high strength, dense and crack-free parts even though AA6061 is challenging for laser additive manufacturing processes due to hot-cracking issues. Design/methodology/approach The multilayers AA6061 parts were fabricated by LFP to characterize for cracks and porosity. Mechanical properties of the LFP-fabricated AA6061 parts were tested using Vicker’s microhardness and tensile testes. The electron backscattered diffraction (EBSD) technique was used to reveal the grain structure and preferred orientation of AA6061 parts. Findings The crack-free AA6061 parts with a high relative density of 99.8% were successfully fabricated using the optimal process parameters in LFP. The LFP-fabricated parts exhibited exceptional tensile strength and comparable ductility compared to AA6061 samples fabricated by conventional laser powder bed fusion (LPBF) processes. The EBSD result shows the formation of cracks was correlated with the cooling rate of the melt pool as cracks tended to develop within finer grain structures, which were formed in a shorter solidification time and higher cooling rate. Originality/value This study presents the pioneering achievement of fabricating crack-free AA6061 parts using LFP without the necessity of preheating the substrate or mixing nanoparticles into the melt pool during the laser melting. The study includes a comprehensive examination of both the mechanical properties and grain structures, with comparisons made to parts produced through the traditional LPBF method.

Experimental, Computational, and Machine Learning Methods for Prediction of Residual Stresses in Laser Additive Manufacturing: A Critical Review

“…where ϵ is emissivity, σ is Stephen Boltzmann's constant, and T s and T ∞ represent the surface and room temperature, respectively. Sometimes, the above-mentioned loss of heat can be considered as a combined heat loss, as shown in Equations ( 10) and (11).…”

“…Residual stresses in AM result from uneven cooling rates and thermal gradients during material deposition and solidification [8]. Residual stresses and distortion in AM can undermine part quality and integrity, posing significant challenges such as decreased fatigue strength, shrinking, and bending [9][10][11]. Potential applications of metal additive manufacturing include the manufacturing of complex free-form part designs and customization in aerospace [12][13][14], automotive [15], and biomedical applications [16].…”