*Article* **Erosion Resistance and Particle Erosion-Induced Tensile Embrittlement of 3D-Selective Laser MeltingInconel 718 Superalloy**

#### **Jun-Ren Zhao, Fei-Yi Hung \* and Truan-Sheng Lui**

Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan; a2x346yz03@gmail.com (J.-R.Z.); luits@mail.ncku.edu.tw (T.-S.L.)

**\*** Correspondence: fyhung@mail.ncku.edu.tw; Tel.: +886-6-275-7575 (ext. 62950)

Received: 31 October 2019; Accepted: 20 December 2019; Published: 22 December 2019

**Abstract:** We used selective laser melting (SLM) Inconel 718 (coded AS) to carry out three heat treatment processes: (1) double aging (coded A), (2) solid solution + A (coded SA), (3) homogenization + SA (coded HSA) in order to investigate the e ffects of microstructure changes and tensile strength enhancement on erosion resistance. The as-SLM IN718 and three heat-treated specimens were subjected to clarify the e ffects of erosion-induced phase transformation on tensile mechanical properties. All heat-treated specimens showed better erosion resistance than as-SLM IN718 did at all impact angles. The as-SLM IN718 and the three heat-treated specimens produced new γ phase or metal-oxide via particle erosion, which increased the surface hardness of the material. The thickness of the erosion a ffected zone is 200 μm, which is the main cause of tensile embrittlement.

**Keywords:** Inconel 718; selective laser melting (SLM); erosion; phase transformation; tensile; embrittlement
