Design of novel materials for additive manufacturing - Isotropic microstructure and high defect tolerance

Area of Science:

• Materials Science
• Metallurgy
• Additive Manufacturing

Background:

• Electron Beam Melting (EBM) is an additive manufacturing technique for complex metallic parts.
• EBM materials performance is limited by difficult-to-control factors like anisotropy and defects.
• Cubic crystal structures often exhibit anisotropy due to columnar grains.

Purpose of the Study:

• Investigate the processing of metastable austenitic CrMnNi steel using EBM.
• Analyze the impact of EBM on microstructure, defects, and mechanical properties.
• Determine the optimal process window for CrMnNi steel via EBM.

Main Methods:

• Processing of metastable austenitic CrMnNi steel via Electron Beam Melting (EBM).
• Utilized various scan strategies to control microstructure evolution and defect formation.
• Characterized microstructure, porosity, and chemical composition changes.

Main Results:

• EBM processing resulted in a fine-grained microstructure with minimal crystallographic orientation.
• The material exhibited deformation-induced phase transformation, enhancing damage tolerance.
• Mechanical properties were less sensitive to process-induced inhomogeneities.

Conclusions:

• Metastable austenitic CrMnNi steel processed by EBM shows promising results for additive manufacturing.
• The fine-grained, isotropic microstructure and deformation-induced phase transformation contribute to excellent mechanical properties.
• EBM offers a viable route for producing high-performance CrMnNi steel parts with reduced anisotropy and defect sensitivity.