Investigating mechanical and surface porosity values of high-performing 3D-printed titanium alloys along with stress-relieving heat treatments

• Published in: International journal of advanced manufacturing technology 2023-12, Vol.129 (11-12), p.4939-4960
• Main Authors: Subeshan, Balakrishnan, Asmatulu, Eylem, Ma, Annie Tran, Bakir, Mete, Asmatulu, Ramazan
• Format: Article
• Language: English
• Subjects: Additive manufacturing; CAE) and Design; Computer-Aided Engineering (CAD; Diamond pyramid hardness tests; Engineering; Heat treating; Heat treatment; Industrial and Production Engineering; Laser sintering; Manufacturing; Mechanical Engineering; Mechanical properties; Media Management; Metal powders; Modulus of elasticity; Original Article; Oxidation; Porosity; Production methods; Rockwell hardness; Sintering (powder metallurgy); Surface properties; Surface roughness; Three dimensional printing; Titanium alloys; Titanium base alloys
• ISSN: 0268-3768; 1433-3015
• DOI: 10.1007/s00170-023-12552-1

Additive manufacturing using metal powders is becoming increasingly popular due to its versatility in creating structural components of various shapes. Among the various additive manufacturing methods (or 3D printing), direct metal laser sintering (DMLS) is one of the most frequently used technologies. The material most frequently used in DMLS technology is the titanium (Ti 6 Al 4 V) alloy, widely preferred in defense, aerospace, automotive, energy, and biomedical industries. This research study examines the mechanical and surface porosity and roughness properties of the 3D-printed Ti 6 Al 4 V (Grade 23) alloy specimens. In addition to additive manufacturing, a post-processing treatment known as stress-relieving (SR) heat treatment is also utilized for additively manufactured specimens. Four differently shaped walls (diamond, square, circle, and hexagon) were additively manufactured. The mechanical properties of the 3D-printed Ti 6 Al 4 V alloy specimens were tested using compression testing and hardness tests using Rockwell and Vickers scales. These tests were conducted before and after post-process SR heat treatment. Additionally, surface roughness analysis was conducted on the specimens to determine any changes in the material’s surface properties after the SR heat treatment. It was observed that the heat-treated (HT) specimens existed to have more cracks and oxidation compared to the non-heat-treated (NHT) ones. According to the surface roughness results, the circular-shaped heat-treated wall (CSHTW) specimen has the lowest average roughness (Ra) value of 210.31 µin (5.34 µm), and the corresponding maximum height (Rz) was 897.99 µin (22.81 µm). Also, the average Rockwell hardness value of the HT specimens was reported to present an increase of approximately 3% compared to the NHT specimens. The diamond-shaped heat-treated wall (DSHTW) specimen exhibited the highest Vickers hardness value of 605.08 (± 233.98) HV. It was found that the CSHTW specimens had the highest elastic modulus and yield strengths among all the geometries, with a value 38 GPa and 1380 MPa, respectively, indicating that they could resist deformation better than the other specimens. Overall, this study is important because additively manufactured Ti 6 Al 4 V alloy components are increasingly used in many industries, as it offers significant reductions in costs, material waste, manufacturing lead times, and improved performance outcomes.