Comparison of the machinability of the 316L and 18Ni300 additively manufactured steels based on turning tests

This paper focuses on the machinability of additively manufactured steel alloys (316L stainless steel and 18Ni300 Maraging steel) by reference to their conventional metallurgical conditions. The machinability of both metallurgical conditions has been evaluated by longitudinal turning tests under laboratory conditions using two different cutting tool geometries (flat rake face and chip-breaker geometry) and covering different cutting speeds, depths of cut and feed values. Cutting forces, chip morphology and surface roughness were investigated as machinability indicators. The influence of chip-breaker on process performance was also analysed. For a comprehensive discussion of the results, microstructure, chemical composition, surface roughness and mechanical strength of both metallurgical conditions were studied. The paper quantitatively demonstrates that despite the higher mechanical strength of additively manufactured alloys, no significant power requirements were verified for the finishing cutting of tested alloys, when compared with conventional materials. Also noteworthy, is the surface quality improvement of the printed samples due to the most favourable conditions for chip formation. The usage of a chip breaker insert had higher impact on reducing required cutting energy than on controlling chip geometry.

Study of Temperature Distribution and Material Flow for different pin profile in Friction Stir Welding of AA6061-T6

A fully-coupled 3-D model of FSW was developed for 4 mm plates of AA6061-T6 aluminum alloy based on the Finite Volume Method (FVM) in ANSYS Fluent 14.5 software. Two types of the model; one with the tool and another without the tool was developed for different tool geometry and analysis was done for temperature distribution in the workpiece as well as in tool using system coupling for the first model and workpiece only in later one. A parametric study was performed at different tool rotational speed regarding temperature distribution, and material flow analysis was carried out for all tool geometries at a single rotational speed. The material behaves differently when passes through the different tools and it was affected by thermal history, viscosity, and strain rate for particular tool geometry. Temperature-dependent material properties and a user-defined function (UDF) code of viscosity have been incorporated in the model considering the workpiece as a non-Newtonian viscous fluid. A better material mixing was observed in the case of threaded pin geometry by using a steady-state laminar flow model. All tapered tool geometries were unable to mix material properly just below and around the pin tip due to very low-velocity magnitude in this region, which may lead to a kind of defect. An asymmetric temperature distribution observed in the workpiece and at higher rotational speed peak temperature observed higher in the workpiece, and the flow of heat was more in tool. Validation of the model was done by performing experiments.

Additive Friction Stir Deposition for Fabrication of Silicon Carbide Metal Matrix Composites

Additive friction stir deposition is an emerging solid-state additive manufacturing technology that has shown promise for bulk fabrication of metals and metal-matrix composites. Here, we perform a preliminary investigation into the influence of tool geometries on the particle distribution and matrix-particle coherence of SiC in the matrix of Aluminum Alloy 6061 and commercially pure Copper. Two tool geometries have been used: (1) a simple, featureless tool and (2) a complex geometry tool with four surface protrusions. For the simple tool geometry, the Al-SiC is observed to have less uniform bulk distribution of the reinforcement phase, resulting in regions of highly concentrated SiC reinforcement (up to 69 area%). The Cu-SiC sample produced with the simple geometry tool has a homogeneous distribution. The samples produced with the complex geometry tool show more uniform distribution of SiC reinforcement throughout the bulk of the deposit with local reinforcement concentrations reaching up to 42 area% and 28 area% for the Al and Cu matrix, respectively. All tool geometries create samples with good interfaces that have continuous contact between the particle and matrix phases, even including particles with sharp angles and non-spherical surfaces. Further optimization of tool geometries and processing conditions can lead to improved control of the reinforcement phase distribution and enable design of metal-matrix composites with tailored site-specific properties.

Study of Temperature Distribution and Material Flow in Friction Stir Welding of AA6061-T6

A fully-coupled 3-D model of FSW was developed for 4 mm plates of AA6061-T6 aluminum alloy based on the Finite Volume Method (FVM) in ANSYS Fluent 14.5 software. Two types of the model; one with the tool and another without tool was developed for different tool geometry and analysis was done for temperature distribution in the workpiece as well as in tool using system coupling for first model and workpiece only in later one. A parametric study was performed at different tool rotational speed regarding temperature distribution, and material flow analysis was carried out for all tool geometries at a single rotational speed. The material behaves differently when passes through the different tool and it was affected by thermal history, viscosity and strain rate for particular tool geometry. Temperature-dependent material properties and a user-defined function (UDF) code of viscosity have been incorporated in the model considering the workpiece as a non-Newtonian viscous fluid. A better material mixing observed in case of threaded pin geometry by using a steady-state laminar flow model. All tapered tool geometries were unable to mix material properly just below and around the pin tip due to very low-velocity magnitude in this region, which may lead to a kind of defect. An asymmetric temperature distribution observed in the workpiece and at higher rotational speed peak temperature observed higher in the workpiece, and the flow of heat was more in tool. Validation of the model was done by performing experiments.

Study of Temperature Distribution and Material Flow in Friction Stir Welding of AA6061-T6

A fully-coupled 3-D model of FSW was developed for 4 mm plates of AA6061-T6 aluminum alloy based on the Finite Volume Method (FVM) in ANSYS Fluent 14.5 software. Two types of the model; one with the tool and another without tool was developed for different tool geometry and analysis was done for temperature distribution in the workpiece as well as in tool using system coupling for first model and workpiece only in later one. A parametric study was performed at different tool rotational speed regarding temperature distribution, and material flow analysis was carried out for all tool geometries at a single rotational speed. The material behaves differently when passes through the different tool and it was affected by thermal history, viscosity and strain rate for particular tool geometry. Temperature-dependent material properties and a user-defined function (UDF) code of viscosity have been incorporated in the model considering the workpiece as a non-Newtonian viscous fluid. A better material mixing observed in case of threaded pin geometry by using a steady-state laminar flow model. All tapered tool geometries were unable to mix material properly just below and around the pin tip due to very low-velocity magnitude in this region, which may lead to a kind of defect. An asymmetric temperature distribution observed in the workpiece and at higher rotational speed peak temperature observed higher in the workpiece, and the flow of heat was more in tool. Validation of the model was done by performing experiments.