Experimental analysis and optimization on machining of coated carbon fiber and nanoclay reinforced aluminum hybrid composites

In the present work, free-cutting aluminum alloy AA6026 with 1.1 wt.% bismuth addition was fabricated by different melt preparation methods in order to investigate whether the melt preparation route affects the solidification sequence and thus has an influence on the machinability of the alloy. All experiments were designed to simulate variable industrial conditions: addition of bismuth in an induction melting furnace, addition of bismuth in an electric resistance holding furnace, addition of bismuth together with grain refiner, effect of holding time and melt temperature before casting. Detailed thermodynamic analyses (DSC, Thermo-Calc) and microstructural characterization (SEM-EDS, XRD) have been performed to explain the solidification sequence, microstructure development and especially formation of the intermetallic Mg3Bi2 phase.

https://www.mdpi.com/2073-4352/11/4/424/pdf

Mechanism of the Mg3Bi2 Phase Formation in Pb-Free Aluminum 6xxx Alloy with Bismuth Addition

Pb-based alloys such as AA6262, AA2011 and more recently AA6026 are used as free-machining aluminum alloys for automotive and electronic applications However, in order to comply with Automotive End of Life Vehicles (ELV) and Restriction of Hazardous Substances (RoHS) directives, Pb-based alloys slowly need to be phased out A Pb-free machining grade 6xxx aluminum alloy based on Sn was developed and its machinability evaluated Microstructure analysis of the Al–Mg–Si–Sn–Cu alloy revealed the presence of (98 wt%) Sn–Mg2Sn eutectic phases, which have a low melting point of ~203 °C, and are responsible for providing good machinability Homogenized billets of the alloy were extruded and heat treated to T6 temper Yield strength and ultimate tensile strength of the Pb-free alloy were comparable to those of the conventionally used Pb-based AA6262-T6 alloy Machinability studies of the alloy were conducted by evaluating the effect of cutting speed, feed rate and depth of cut on surface roughness, chip size and form of chip produced during the turning operation The machinability of the Sn containing alloy was found to be superior to that of non-machining grade 6xxx alloys AA6061-T6 and AA6082-T6 and comparable to that of Pb-based free-machining alloy AA6262-T6

V. Siva Raman

Papers

Investigations on Pb-Free 6000 Series Aluminum Alloy for Machining Applications