Effects of Processing and Geometry Parameters on Mass Deviation and Microstructure Evolution in Selective Laser...

Area of Science:

• Materials Science
• Additive Manufacturing
• Mechanical Engineering

Background:

• Selective laser melting (SLM) is a key additive manufacturing technique for 316L stainless steel lattice structures (LSs).
• Achieving precise fine struts with minimal defects and uniform microstructure in SLM-fabricated LSs remains a significant challenge.
• Understanding the interplay of processing and geometric parameters is crucial for controlling the quality of SLM-produced components.

Purpose of the Study:

• To quantify the effects of geometric (forming angle, rod diameter) and processing (laser power, scanning speed, hatch spacing) parameters on the mass deviation of fine struts in 316L stainless steel LSs.
• To investigate the microstructural evolution, including solidification morphology, defect distribution, crystallographic texture, and geometrically necessary dislocation (GND) density, in response to variations in forming angle and rod diameter.
• To establish geometric parameters as effective design variables for controlling forming deviation and microstructure in SLM-fabricated 316L LSs.

Main Methods:

• Response surface methodology (RSM) and analysis of variance (ANOVA) were utilized to model and analyze the impact of multiple parameters on mass deviation.
• Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Electron Backscatter Diffraction (EBSD) were employed for detailed microstructural characterization.
• Systematic variation of forming angle (FA) and rod diameter (RD) to observe their influence on strut characteristics.

Main Results:

• Forming angle (FA) and rod diameter (RD) were identified as the dominant factors influencing mass deviation (MD) of fine struts.
• Laser power (LP) and scanning speed (SS) showed less significant effects on MD within the studied range.
• Higher FA correlated with reduced MD and enhanced texture alignment along the building direction.
• Increased RD promoted columnar grain growth and higher texture intensity.
• Microstructural analysis revealed that changes in FA and RD directly impact solidification morphology, defect presence, texture, and GND density.

Conclusions:

• Geometric parameters, specifically forming angle and rod diameter, are critical for controlling mass deviation and microstructural features in fine struts of SLM-fabricated 316L stainless steel lattice structures.
• Forming angle and rod diameter can be leveraged as design tools to tailor the dimensional accuracy and microstructure of additively manufactured components.
• This study provides insights into optimizing SLM process parameters for producing high-quality, lightweight 316L stainless steel lattice structures with desired properties.