本研究以中等的雷射功率範圍 (120 W - 180 W) 對 17-4 PH 不鏽鋼進行選擇性雷射熔融積層製造。針對不同製程條件下之工件，比較其密度、硬度、表面粗糙度、金相與孔洞率。然後選取一組材料強度較高與孔洞率較少的參數組合，量測該工件之拉伸、固定負荷振幅疲勞及變動負荷振幅疲勞性質，並探討其疲勞壽命預測模式。 研究結果顯示，在密度、硬度、表面粗糙度、孔洞率方面，當列印能量密度越高時，材料會呈現較高的密度值，與較高的硬度值。同時還有較低的表面粗糙度，與較少的孔洞率。列印參數組合為雷射功率 140 W、掃描速率 800 mm/s、掃描間距 80 μm、層厚 30 μm 之試件具有較高材料強度與較少孔洞率。本研究的選擇性雷射熔融積層製造工件的疲勞 S-N 曲線雖然小於鍛造試件，但是大於採用其他雷射功率 (250 W、220 W、48 W) 列印的工件。在固定負荷振幅疲勞方面，平均應力之修正以採用 Soderberg 方程式為最佳。在變動負荷振幅疲勞方面，不論是傳動軸歷程或支架歷程，Soderberg 修正式及 Goodman 修正式皆適用於預測 17-4 PH 不鏽鋼積層製造工件之疲勞壽命。;In this study, selective laser melting (SLM) manufacturing was performed on 17-4 PH stainless steel in a moderate laser power range (120 W - 180 W). The density, hardness, surface roughness, metallography and porosity of the workpiece under different processing conditions were compared. Then a combination of the process parameters is selected, which has higher strength and less porosity. The properties of tensile, constant load amplitude fatigue and variable load amplitude fatigue were measured, and the fatigue life prediction model was discussed. The results show that the higher the printing energy density is, the higher the density and hardness will be. At the same time, it also has lower surface roughness and less porosity. The test sheet with laser power 140 W, scanning speed 800 mm/s, hatching spacing 80 μm, and layer thickness 30 μm has higher strength and less hole ratio. The S-N curve of the specimens in this study is lower than that of the wrought specimen, but it is higher than the curves printed by SLM with other laser powers (250 W, 220 W, 48 W). The Soderberg equation is the best method to correct the mean stress effect under constant amplitude fatigue loading. Soderberg′s mean stress modification or Goodman′s mean stress modification methods are applicable to predict fatigue life of 17-4 PH workpiece produced by SLM, whether transmission or bracket load histories developed by the Society of Automotive Engineers.
