Influence of Scanning Strategy on Residual Stresses in Laser-Based Powder Bed Fusion Manufactured Alloy 718: Modeling...

Area of Science:

• Materials Science and Engineering
• Mechanical Engineering
• Additive Manufacturing

Background:

• Residual stresses are a significant challenge in additive manufacturing (AM), leading to part defects such as cracking and distortion.
• These stresses can compromise the in-service performance and structural integrity of components produced via AM.
• Laser-based powder bed fusion (PBF-LB) is a prominent AM technique where managing residual stresses is critical for build success.

Purpose of the Study:

• To develop and validate computational models for predicting residual stresses and deformation in PBF-LB parts.
• To investigate the influence of different scanning strategies on mitigating unwanted outcomes like cracking and distortion.
• To enhance the understanding of thermo-mechanical behavior during the PBF-LB process.

Main Methods:

• Development of a thermo-mechanical finite element model incorporating a mechanism-based material model to account for relaxation effects.
• Calibration of a purely mechanical model using the inherent strain method to simulate various scanning strategies.
• Experimental validation using high-energy synchrotron measurements to compare predicted residual stress fields with actual data.

Main Results:

• Both the thermo-mechanical and inherent strain models successfully captured the trend of experimentally measured residual stress fields.
• The models adequately predicted part deformations, although their magnitude was generally underpredicted.
• Scanning strategies significantly impact residual stresses and deformation patterns in PBF-LB manufactured parts.

Conclusions:

• The developed models provide valuable insights into the thermo-mechanical phenomena governing PBF-LB.
• The study highlights the effectiveness of computational modeling in optimizing scanning strategies for residual stress reduction.
• Findings contribute to improving the reliability and performance of components produced through additive manufacturing.