17-4析出強化不鏽鋼是最廣泛應用的工程材料之一，並為現今雷射熔融積層製造的主要研究課題。不同於傳統製程，雷射熔融積層製造中較高的冷卻速率對於材料的相組成以及微結構有著極大的影響。本研究使用眾多雷射參數，藉由改變雷射線距、掃描速度以及功率產生由不同雷射能量密度製造之試片。藉由相定量分析得知受雷射能量密度及後熱處理製程影響之殘留沃斯田鐵及麻田散鐵相比例。維氏硬度測試及拉伸測試用於釐清對於機械性質所造成之影響。本研究證實了雷射能量密度及後熱處理製程可調控17-4析出強化不鏽鋼之麻田散鐵相比例以及機械性質，提供了17-4析出強化不鏽鋼雷射熔融積層製造上的新觀點。

17-4 PH stainless steel (17-4 PH SS) is one of most widely used engineering material and has been a subject for Selective Laser Melting (SLM) process study. Different from traditional manufacturing process, SLM provide ultra-high cooling rate, which would dramatically influence the phase formation and microstructure of the built material. In this work, numerous scanning parameters including different laser hatch distance, scan speed and power were used to fabricate SLM specimens with variant energy density. Phase fraction analysis via Quantitative Phase Analysis (QPA) method revealed proportion of retained austenite and martensite phases influenced by energy density and post heat-treatment. Vickers hardness test and tensile test were performed to clarify the effects on mechanical properties. This work demonstrates that energy density and post heat-treatment can control the martensitic phase fraction and mechanical properties, providing new prospect on SLM manufacturing process for 17-4 PH stainless steel.

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