High-Temperature Elongation Reaches 23.1%: AmPro Innovations Powers Breakthrough IN718 Alloy Toughness Research at Monash University

Laser Powder Bed Fusion (LPBF) is a cutting-edge additive manufacturing (AM) technique that constructs complex three-dimensional parts by selectively melting metal powders with a laser beam. However, challenges such as powder spattering, balling, and powder humidity during the LPBF process often lead to surface roughness, lack-of-fusion defects, and compromised mechanical properties. These issues are especially pronounced when printing high-temperature alloys like IN718, where achieving consistent densification and microstructural uniformity is critical for reliable thermal performance. To tackle these obstacles, repeated laser remelting has emerged as a promising strategy to enhance surface quality, promote densification, and improve mechanical strength.

A Novel Remelting Strategy from Monash University Team

To address these longstanding challenges, a research team from Monash University, in collaboration with Soochow University and Jiangxi University of Science and Technology, developed an innovative remelting strategy based on a time-sequenced energy input model. By strategically adjusting the remelting sequence, they were able to modulate the thermal history of the build, significantly reducing porosity and enhancing mechanical performance.

Compared to conventional preheating approaches, specimens produced using the remelting strategy demonstrated markedly superior mechanical properties. As-printed samples yielded the following results:

* Vertical direction:

  * Ultimate tensile strength (UTS): 874.0 MPa

  * Yield strength: 615.3 MPa

  * Elongation: 22.6%

* Horizontal direction:

  * UTS: 1009.3 MPa

  * Yield strength: 727.7 MPa

  * Elongation: 23.4%

Following heat treatment, the remelted samples exhibited exceptional high-temperature mechanical performance:

* Vertical direction (post-treatment):

  * UTS: 959.7 MPa

  * Yield strength: 792 MPa

  * Elongation: 23.1%

Technical Insights and Industrial Significance

Beyond performance metrics, the study provides valuable insights into the mechanisms behind defect formation in LPBF and proposes a viable pathway for defect suppression via remelting sequence design. This offers significant implications for the development of in-situ monitoring and defect control strategies in LPBF manufacturing.

Notably, the remelting approach demonstrated stable surface roughness across varying conditions, suggesting that adaptive remelting—triggered by real-time surface morphology feedback—could enable closed-loop control. This has the potential to reduce reliance on ultra-smooth surfaces at each layer, thereby enhancing process stability and production efficiency.

Future optimizations of the LPBF process, the study argues, should move beyond traditional energy density management to include deliberate remelting sequence design. Such innovations are particularly vital for mission-critical applications that demand near-full densification and ultra-low defect rates.

Published Research and Industry Collaboration

The findings were published in the prestigious journal *Additive Manufacturing* under the title:

“Influence of remelting sequence on defect generation and high-temperature mechanical properties in laser powder bed fusion of IN718 alloys.”

AmPro Innovations provided equipment support for this research. Using the Befon SP261 system, the team successfully fabricated IN718 nickel-based superalloy samples exhibiting outstanding toughness and mechanical performance—marking a major breakthrough in high-performance material development.

With its advanced equipment and expert services, AmPro Innovations has become a trusted partner to leading Chinese research institutions, including the China Academy of Engineering Physics, Institute of Metal Research (Chinese Academy of Sciences), Northwestern Polytechnical University, Southeast University, Wuhan University, and Sichuan University. Moving forward, AmPro Innovations will continue strengthening these collaborations, enhancing machine capabilities, and supporting breakthrough innovations in advanced materials—contributing to China’s technological progress and scientific leadership.