Precision Modification of Microstructure and Properties Through Laser Engraving

• Published in: JOM (1989) Vol. 73; no. 12; pp. 4211 - 4220
• Main Authors: Small, Kathryn A., McCue, Ian D., Johnston, Katrina S., Donaldson, Ian, Taheri, Mitra L.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.12.2021; Springer Nature B.V
• Subjects: Carbon; Characterization and Synthesis; Chemistry/Food Science; Cooling; Cooling rate; Corrosion resistance; Dislocation density; Earth Sciences; Engineering; Engraving; Environment; Evolution; Fatigue life; High temperature; Laser cooling; Laser processing; Lasers; Martensitic transformations; Mechanical properties; Metal fatigue; Microscopy; Microstructure; Misalignment; Optical microscopy; Physics; Powder metallurgy; Short Pulsed Lasers for Materials Modification; Simulation; Sintering (powder metallurgy); Steel; Surface treatment; Temperature; Temperature profiles
• ISSN: 1047-4838; 1543-1851
• DOI: 10.1007/s11837-021-04959-6

Laser processing results in modified mechanical properties and microstructural evolution due to high temperatures and fast cooling rates. Different laser surface treatment techniques are under investigation for their potential to alter local microstructure and properties while maintaining properties of the bulk material. Fatigue life of laser-engraved powder metallurgy steel is shown to be significantly reduced compared to as-sintered material, suggesting a degree of microstructural modification with engraving. The misorientation, dislocation density, and phase of samples engraved with a 2D matrix pattern using one laser pass and five laser passes are characterized using optical microscopy and SEM-EBSD, and a CFD simulation of the laser process quantifies the temperature profile of each laser engraving. Deep-engraved samples are seen to result in a possible martensitic transformation at the surface of the engraved region because of increased time at elevated temperature and extreme cooling rates. These findings reinforce the importance of understanding microstructural evolution during precision tailoring via laser surface modification.