This research explores the importance of the powder feedstock characteristics on the manufacturing of martensitic stainless steel elements by Laser Metal Deposition (LMD). Water- and gas-atomised (WA and GA respectively) powders are the most common feedstock material used in LMD. The atomisation process medium influences powder properties including particle size distribution, inner and outer morphology, and microstructure. In this work, commercial WA and GA powders of AISI 431 stainless steel alloy were used to produce LMD coatings under identical deposition parameters. It was found that the powder processing route significantly affected the powder’s morphology, and this led to large changes in the laser energy absorbance during LMD. Consequently, significant changes in the microstructure of the deposited layer were observed. The parts manufactured with WA powder presented a duplex structure composed of martensite and ferrite, while a predominantly martensitic structure was verified in the GA deposition. The microstructural differences led to a wear rate reduction by a factor of 35 and a gain of 150 mV in pitting potential in the GA material. Though, the application of GA powder increased the production cost by 53% due to its lower deposition efficiency and higher retail price. The marked differences have all been attributed to the characteristics of the starting powder feedstock. This work highlights that the properties of the powder feedstock are a critical parameter in determining the properties of the LMD material, and emphasises the importance of the powder processing route on the energy absorption during LMD.

本研究探讨了粉末原料特性对通过激光金属沉积 (LMD) 制造马氏体不锈钢元件的重要性。水雾化和气雾化（分别为 WA 和 GA）粉末是 LMD 中最常用的原料。雾化工艺介质会影响粉末特性，包括粒度分布、内部和外部形态以及微观结构。在这项工作中，AISI 431 不锈钢合金的商业 WA 和 GA 粉末用于在相同的沉积参数下生产 LMD 涂层。结果表明，粉末加工路线显着影响了粉末的形貌，这导致了 LMD 过程中激光能量吸收的较大变化。因此，观察到沉积层微观结构的显着变化。用 WA 粉末制造的零件呈现出由马氏体和铁素体组成的双相结构，而在 GA 沉积中证实了主要是马氏体结构。微观结构的差异导致磨损率降低了 35 倍，GA 材料的点蚀电位增加了 150 mV。然而，由于其较低的沉积效率和较高的零售价，GA粉末的应用使生产成本增加了53%。显着的差异都归因于起始粉末原料的特性。这项工作强调了粉末原料的性质是决定 LMD 材料性质的关键参数，并强调了粉末加工路线对 LMD 过程中能量吸收的重要性。