Abstract
Metal additive manufacturing (AM) is a low-cost, high-efficiency functional mold manufacturing technology. However, when the functional section of the mold or part is not a partial area, and large-area additive processing of high-hardness metal is required, cracks occur frequently in AM and substrate materials owing to thermal stress and the accumulation of residual stresses. Hence, research on residual stress reduction technologies is required. In this study, we investigated the effect of reducing residual stress due to thermal deviation reduction using a real-time heating device as well as changes in laser power in the AM process for both high-hardness cold and hot work mold steel. The residual stress was measured using an X-ray stress diffraction device before and after AM. Compared to the AM processing conditions at room temperature (25 °C), residual stress decreased by 57% when the thermal deviation was reduced. The microstructures and mechanical properties of AM specimens manufactured under room-temperature and real-time preheating and heating conditions were analyzed using an optical microscope. Qualitative evaluation of the effect of reducing residual stress, which was quantitatively verified in a small specimen, confirmed that the residual stress decreased for a large-area curved specimen in which concentrated stress was generated during AM processing.
Highlights
Additive manufacturing (AM) processing technology has been gaining increasing interest globally
additive manufacturing (AM) technology is classified according to the additive method as material extrusion (ME), material jetting (MJ), binder jetting (BJ), sheet lamination (SL), vat photo polymerization, powder bed fusion (PBF), and direct energy deposition (DED) [4,5]
4 depicts trial product amount carbide that, during the liquid phase section is extended owing to the the non-equilibrium of the residual stress residual fabrication concept and the location measurement applied to the stress reaction, and a large amount of crystallized carbide is generated
Summary
Additive manufacturing (AM) processing technology has been gaining increasing interest globally. To solve the deformation and residual stress problems that occur during the AM process, previous studies have attempted to predict the thermal and mechanical behavioral effects of metal AM using finite element (FE)-based thermodynamic modeling and determine the optimal process parameters for the relaxation of the generated deformation and residual stress [18,19,20,21] These previous studies investigated the AM process in a simple trial product unit for the thermodynamic analysis of the AM process, and only a few studies on the residual stress reduction technology considered the additive processing of large high-hardness materials. The results were used to suggest a plan for reducing residual stresses
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