Directed laser deposition of super duplex stainless steel: Microstructure, texture evolution, and mechanical...

Area of Science:

• Materials Science
• Metallurgy
• Additive Manufacturing

Background:

• Super-duplex stainless steels are crucial for demanding applications.
• Directed laser deposition (DLD) offers advanced manufacturing capabilities.
• Understanding DLD's effect on material properties is vital for optimizing performance.

Purpose of the Study:

• Characterize microstructure and texture evolution in DLD super-duplex stainless steel.
• Investigate the relationship between microstructure, texture, and mechanical properties.
• Analyze the impact of deposition parameters on material anisotropy and performance.

Main Methods:

• Light and electron microscopy for microstructural analysis.
• Electron backscattered diffraction (EBSD) for texture and phase distribution.
• Mechanical property testing in various directions (hardness, tensile, impact).

Main Results:

• Detected local FCC-depleted/rich zones, oxide precipitation, and reformed austenite.
• Observed a vertical austenite content gradient and corresponding hardness decrease along the build direction.
• Identified distinct ferrite and austenite texture components varying with deposition layer, with Kurdjumov-Sachs orientation relationship dominating inter-phase boundaries.

Conclusions:

• The complex transformation texture of austenite depresses mechanical anisotropy.
• The material exhibits brittleness, characterized by high tensile strength and low impact toughness.
• Cooling rate variations during DLD significantly influence microstructure, texture, and mechanical behavior.