Effect of Energy Input on the Characteristic of AISI H13 and D2 Tool Steels Deposited by a Directed Energy Deposition Pr
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ADDITIVE manufacturing (AM) technology has attracted attention because it can produce complex parts directly from three-dimensional computer-aided design models.[1] Additionally, it is interesting as a green manufacturing technology since the loss of materials is minimized. The direct energy deposition (DED) process[1] is an AM technology for metal deposition and has the advantages of the simultaneous use of many nozzles, rapid manufacturing rate, and relatively few limitations on the working size. Thus, the DED process has been widely used for re-work, such as the restoration of damaged steel dies, or for adding functionality on the surface by deposition of different materials on the existing part.[2–5] Metal deposited by the DED process has different properties than wrought metal because of the rapid solidification rate, the high thermal gradient between the deposited metal and substrate, etc.[5–9] In particular, there are many reports on the hardness of deposited steels.[6–9] Mazumder et al.[6,7] found that the hardness of AISI H13 steel, fabricated by the direct materials deposition (DMD) process based on the DED process, was greater than that of wrought H13 steel. In addition, the characteristics of metal deposited by the DED JUN SEOK PARK and MIN-GYU LEE, Researchers, JI HYUN SUNG, Principal Researcher, and KYOUNG JE CHA and DA HYE KIM, Senior Researchers, are with the Ultimate Manufacturing Technology Group, Korea Institute of Industrial Technology, Daegu 711-883, Korea. Contact e-mail: [email protected] JOO HYUN PARK, Professor, is with the Department of Materials Engineering, Hanyang University, Ansan 426-791, Korea. Manuscript submitted October 5, 2015. Article published online March 8, 2016 METALLURGICAL AND MATERIALS TRANSACTIONS A
process depend upon various operating parameters, such as laser power, beam diameter, traverse speed, powder mass flow rate, etc.[2,11–18] Jang et al.[2] investigated the effect of laser energy density on the deposition shape in the direct laser melting (DLM) process using Fe-Cr and Fe-Ni powder. They reported that lower scan rates at higher laser powers caused the metal powder and part of the substrate to vaporize, while insufficient bonding was observed at lower and higher scan rates.[2] Majumdar et al.[16,17] studied the microstructural and mechanical properties of 316L stainless steel produced by laser-assisted rapid fabrication. They found that the grain size of the deposited 316L stainless steel decreased with increasing scan speed and that the hardness decreased with increasing laser power density. Despite previous reports, the process of tuning the characteristics of deposited materials by controlling operating parameters is still not clearly understood. In this study, we investigated the effect of energy input on the hardness and chemical composition of AISI H13 and D2 tool steels deposited by the direct metal tooling (DMT) process based on the DED process. In particular, for application to the restoration of damaged tool products, we discuss the possibility of th
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