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<p>Porosity of the manufactured piece in laser-based Direct Energy Deposition (DED) of 316L stainless steel remains a critical limitation, primarily associated with temperature drift and heat accumulation, which destabilize the melt pool and promote the formation of grain defects. To address this issue, this work introduces an online fuzzy–pulsed temperature regulation strategy based on non-invasive thermographic feedback. The method employs infrared monitoring to capture the maximum surface temperature (hot spot) as an indicator of the process thermal state, together with a Mamdani-type fuzzy inference system. The controller evaluates the temperature deviation and its time derivative to define interlayer repositioning conditions (laser off), enabling controlled cooling and pulse-like thermal regulation without laser power modulation or firmware access. The strategy is implemented through the DEDRA post-processor, which embeds the inferred adjustments directly into the G/M-code. Experimental validation on rectangular prismatic 316L specimens processed at low power (200 and 250 W) shows that the proposed strategy reduces porosity to below 1%, improves hatch spacing and interlayer height consistency (with deviations under 5%), and decreases variability across repeated trials compared to uncontrolled deposition. Microstructural analysis revealed refined cellular–dendritic morphologies with secondary dendrite arm spacing below 5&#xa0;<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\upmu\)</EquationSource> </InlineEquation>m, along with compositional uniformity and fully austenitic grains. Resulting microhardness values are comparable to or exceed those of forged 316L stainless steel. Overall, the results demonstrate a practical, hardware-independent thermal regulation framework for improving density, dimensional accuracy, and microstructural quality in low-power DED.</p>

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Fuzzy pulsed temperature regulation for reduced porosity in direct energy deposition of 316L stainless steel

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年6月3日

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  • Edison Luis Sanchez Maldonado,
  • Jorge Isaac Chairez Oria,
  • Elisa Virginia Vazquez Lepe,
  • Jose Israel Martinez Lopez

摘要

Porosity of the manufactured piece in laser-based Direct Energy Deposition (DED) of 316L stainless steel remains a critical limitation, primarily associated with temperature drift and heat accumulation, which destabilize the melt pool and promote the formation of grain defects. To address this issue, this work introduces an online fuzzy–pulsed temperature regulation strategy based on non-invasive thermographic feedback. The method employs infrared monitoring to capture the maximum surface temperature (hot spot) as an indicator of the process thermal state, together with a Mamdani-type fuzzy inference system. The controller evaluates the temperature deviation and its time derivative to define interlayer repositioning conditions (laser off), enabling controlled cooling and pulse-like thermal regulation without laser power modulation or firmware access. The strategy is implemented through the DEDRA post-processor, which embeds the inferred adjustments directly into the G/M-code. Experimental validation on rectangular prismatic 316L specimens processed at low power (200 and 250 W) shows that the proposed strategy reduces porosity to below 1%, improves hatch spacing and interlayer height consistency (with deviations under 5%), and decreases variability across repeated trials compared to uncontrolled deposition. Microstructural analysis revealed refined cellular–dendritic morphologies with secondary dendrite arm spacing below 5  \(\upmu\) m, along with compositional uniformity and fully austenitic grains. Resulting microhardness values are comparable to or exceed those of forged 316L stainless steel. Overall, the results demonstrate a practical, hardware-independent thermal regulation framework for improving density, dimensional accuracy, and microstructural quality in low-power DED.