直接能量雷射沉積(DED)為一種金屬3D列印技術，適合用於生產航太、生醫等高複雜度金屬零件與修補損壞設備，由於大多用於特殊需求環境或是有高穩定性要求，因此探討成品的機械性質與微結構相當重要。

本研究探討影響DED製程品質最直接相關的雷射瓦數，並實際以316L不鏽鋼粉末垂直沉積多層成品。考量現實應用中多重應力下的效應，以三點抗彎試驗對沉積物施以應力變形，並結合數位影像相關法(DIC)量測其機械性質與應變分布，微結構方面以背向電子散射繞射儀技術(EBSD)分析在受拉伸、壓縮應力與中性區間的微結構演變。

實驗結果顯示，雷射瓦數800 W至1600 W之中低瓦雷射，隨雷射瓦數越高，中心晶粒越粗化，使降伏強度呈現下降趨勢，在1600 W至2000 W之高瓦雷射，隨雷射瓦數提高，降伏強度提升，並由Schmid Factor分布發現在2000 W粗化之晶粒有較低的值；由DIC量測之應變分布結果發現在低瓦數時有較高之拉伸應變值且分布較均勻，隨瓦數提升應變值下降，然而在高瓦數下發現應變局部集中在特定晶粒上。在微結構演變方面，極圖演變中發現拉伸與壓縮的應力造成極面分布沿ND軸旋轉，旋轉方向取決於晶粒取向，<001>取向晶粒貢獻RD軸旋轉、<101>取向晶粒貢獻TD軸旋轉；反極圖顯示在拉伸應力下大多發生向反極圖上方之方向滑移，在壓縮應力下則發生向反極圖下方滑移。

Laser power is the most directly relevant process parameter affecting the quality in Direct Energy Deposition (DED) process. In this study, we investigated laser power effect on mechanical properties and microstructure of multi-layer products after vertical deposition of 40 layers using 316L stainless steel powder.
The mechanical properties were analyzed by three-point bending test combined with digital image correlation (DIC) to obtain strain distribution. The microstructure under tensile, compressive stress and neutral regions were analyzed by EBSD.
Considering laser power from 800 W to 2000 W, 800 W has the highest yield stress of 476 MPa and 1600 W the lowest yield stress of 407 MPa due to coarsening effect. By analyzing strain distribution and Schmid factor, 2000 W shows low strain value and low value of Schmid factor resulting in increasing yield stress of 454 MPa.

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