Develop laser powder bed fusion methodologies for the fabrication of metallic parts with tailored microstructures and enhanced performance

1. Conduct research and development on laser powder bed fusion, including material design, processing parameters and heat treatment optimization, microstructure characterization, and mechanical properties evaluation2. Achieve single-crystalline-like microstructure in Inconel 625 via LPBF3. Implement newly developed microstructure control strategies into real applications

Project 1: Crystallographic-Texture-Dependent Mechanical Behaviours of Stainless Steel 316L (SS316L) Processed by Laser Powder Bed Fusion (LPBF)• Investigated the size-microstructure-mechanical property relationship of LPBF-SS316L struts and developed a methodology to clamp the strut samples for reliable tensile test measurements• Developed a novel method that can fabricate single-crystal LPBF-SS316L struts with superior tensile properties: 67% higher in ductility than their polycrystalline counterparts, 1.5-4 times higher in yield strength than the traditionally manufactured single-crystal SS316L• Developed a novel method that can produce single-crystalline-like bulk LPBF-SS316L of various geometries with superior mechanical performance along selected directions (〈110〉 direction: ~100% ductility and >170 J in impact toughness at 77 K; 〈111〉 direction: similar specific strength as cp-Ti and >200 J in impact toughness at room temperature• Developed a novel LPBF methodology that can fabricate single-crystalline-like LPBF-fabricated SS316L bulk and complex components with superior mechanical properties. Conducted an in-depth investigation of the crystallographic-orientation-dependent mechanical behaviours of the components.Project 2: Manufacturability of Different Alloy Systems for LPBF• Developed MATLAB codes that can automatically generate G-code for laser scanning path for a LPBF machine built in-house• Optimized LPBF parameters to suppress cracking and/or porosity of different alloys using both a commercial machine and the machine built in-house• Characterized the density, microstructure and mechanical properties after LPBF and rationalized the microstructure formation using rapid solidification modeling coded via MATLAB• o Investigated different metallic systems including, aluminum alloy, steels, nickel-based superalloys, titanium alloys, intermetallics, and some other alloys like NiCoCrAlY alloy

Project 1: Microstructure and Mechanical Properties of D406A Ultra-High Strength Steel Processed by Laser-TIG Hybrid Welding with filler wires• Optimized the welding parameters to suppress porosity and cold cracking in the welds. Investigated the porosity formation mechanism using thermodynamic calculations• Conducted heat treatment to improve the strength of steel specimens, and investigated the processing-microstructure-property correlation using OM, SEM, EDS, TEM, microhardness tests, tensile tests, Charpy impact tests, and three-point bending testsProject 2: Development of An Automatic Welding System for Joining Rectangular Boxes and Flanges• Led a group of five people, and managed team outputs• Developed the welding process and parameters for the 2Cr13 martensitic stainless steel workpieces• Conducted the structural design using SolidWorks and created a 3D animation demonstration for the welding system