*Article* **Femtosecond Laser Treatment for Improving the Corrosion Resistance of Selective Laser Melted 17-4PH Stainless Steel**

**Lingjian Meng <sup>1</sup> , Jiazhao Long <sup>1</sup> , Huan Yang 1,\* , Wenjing Shen <sup>1</sup> , Chunbo Li <sup>1</sup> , Can Yang <sup>1</sup> , Meng Wang <sup>1</sup> and Jiaming Li <sup>2</sup>**


**Abstract:** Currently, laser surface treatment (LST) is considered the most promising method available within the industry. It delivers precise control over surface topography, morphology, wettability, and chemistry, making the technique suitable for regulating the corrosion behavior of alloys. In this paper, femtosecond laser texturing with different parameters and atmosphere environments was adopted to clarify the effect of surface treatment on the corrosion resistance of selective laser melted (SLM-ed) 17-4PH stainless steel (SS) in a NaCl solution. The experimental results show that, after the heat treatment, the corrosion resistance of the laser-treated samples was enhanced. With the further laser treatment in an argon atmosphere, the oxidation of nanostructural surfaces was avoided. The Cr, Cu, and other alloying elements precipitated on the laser-ablated surface were beneficial to the formation of a passivation film, leading to an improved corrosion resistance performance.

**Keywords:** additively manufacture; 17-4PH stainless steel; femtosecond laser; corrosion resistance
