Selective laser melting of TiC/H13 steel bulk-form nanocomposites with variations in processing parameters
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Selective laser melting of TiC/H13 steel bulk-form nanocomposites with variations in processing parameters Bandar AlMangour, Franklin Yu, and Jenn-Ming Yang, Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095, USA Dariusz Grzesiak, Department of Mechanical Engineering and Mechatronics, West Pomeranian University of Technology, Szczecin, Poland Address all correspondence to B. AlMangour at [email protected] (Received 7 October 2016; accepted 25 January 2017)
Abstract TiC/H13 nanocomposite parts were processed by selective laser melting using various energy densities; one part also underwent hot isostatic pressing (HIP). The effect of energy density and HIPing on densification, microstructure, and hardness were evaluated. It was found that the densification was not largely affected by the energy density, but the HIP-treated sample displayed a large improvement in relative density. With increasing energy density, the microstructures showed high levels of dispersion of nanoparticles, while HIP treatment coarsened the microstructure and induced agglomeration. Both HIP treatment and increased energy density lowered hardness markedly; this was likely due to annealing effects.
Introduction H13, a medium-carbon steel type, is commonly used for hotwork tooling such as drill bits, end mills, and utilize dies for punching, shearing, and forming materials; it is abundant in the industry.[1] H13 steel displays exceptional workability, good weldability, a low coefficient of thermal expansion, and resistance to oxidation and corrosion. Industry tools are often subjected to high loads that are applied quickly and in large temperature gradients; therefore, such tools must be able to withstand these conditions repeatedly without failure and significant deformation. For this reason, it is necessary to explore ways to strengthen and harden these tool steels in order to increase their longevity, save costs and increase efficiency. One way to approach overcoming this challenge is by incorporating hard second-phase carbides into the steel matrix. Particulate-reinforced MMNC (metal matrix nanocomposites) have shown improved wear resistance, reduced cost, isotropic properties, and low density.[2,3] Since stable carbides coarsen more slowly than cementite, they have proven to be more effective at higher temperatures.[4] Adding TiC, which is thermodynamically stable in conjunction with the hard martensitic steel matrix, has shown increased stiffness, hardness, and wear resistance.[4–7] Conventional methods, however, such as casting or powder metallurgy, have displayed major flaws with their respective processing methods. These methods are often complex and time consuming, require costly molds, and can result in coarse grain structure.[8] Due to low working temperature, particle–matrix interfacial bonding is limited, and this may degrade the mechanical properties of the desired product.[9] Also, non-negligible Van der Waals attractive forces in
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metal–matrix composites (MMC) can
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