Femtosecond-Laser-Induced Nanostructure and High Ablation Rate Observed on Nitrided Alloy Steel

• Published in: Journal of laser micro nanoengineering Vol. 10; no. 1; pp. 33 - 37
• Main Author: Yasumaru, Naoki
• Format: Journal Article
• Language: English
• Published: Ibaraki Japan Laser Processing Society 01.02.2015; Reza Netsu Kako Kenkyukai
• Subjects: Ablation (Vaporization technology); Boron steel; Properties; Steel alloys; United States
• ISSN: 1880-0688; 1880-0688
• DOI: 10.2961/jlmn.2015.01.0007

Femtosecond (fs)-laser-induced nanostructuring of mainly nitrided die steel (1.5C-12Cr) was experimentally investigated using die steel that was heat-treated and then plasma nitrided. Nitrided stainless steel (18Cr-8Ni) and low-carbon steel (0.1C) were also used to examine the influence of the alloy composition. Periodic nanostructures were formed in the direction perpendicular to the laser polarization and the mean spacing D increased with the fluence F. The minimum D values for alloy steels containing Cr observed at F around the ablation threshold were 250-285 nm, which corresponds to a size of about λ/3. In contrast, the minimum D for low-carbon steel was larger at 20 to 30% more than those of the alloy steels. In addition, the ablation rate was obtained by analysis of the cross-sectional profiles of craters ablated by superimposed fs-laser pulses. Although the ablation rates for the non-nitrided steels increased linearly with F on a logarithmic scale, it should be noted that the ablation rate for nitrided die or stainless steels increased faster than linearly with F.