https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Fri, 05 Jun 2026 23:02:26 GMT 2026-06-05T23:02:26Z http://hdl.handle.net/10985/13274 Analysis and possible estimation of keyhole depths evolution, using laser operating parameters and material properties FABBRO, Rémy; PEYRE, Patrice; COSTE, Frédéric; GUNENTHIRAM, V; DAL, Morgan; SCHNEIDER, Matthieu The authors propose an analysis of the effect of various operating parameters on the keyhole depth during laser welding. The authors have developed a model that uses the analysis of the thermal field obtained in 2D geometry, which is mainly defined by the characteristic Peclet number. This allows us to show that the dependence of the aspect ratio R of the keyhole with the operating parameters of the process is a function of two parameters: a normalized aspect ratio R0, controlled by the incident laser power and the spot diameter, and a characteristic speed V0 related to the process of heat diffusion. The resulting general law R = f (R0, V/V0) appears to be very well verified by different experimental data and allows to define mean thermophysical parameters of the used materials. These data can then be used for keyhole depths prediction for any subsequent operating parameters of the same material. This model also allows us to define precisely a criterion for a keyhole threshold generation. The authors will apply the derived procedure to successfully analyze experiments on materials with very different thermophysical properties (such as steel alloys and copper), with various focal spots, incident laser powers, and welding speeds. Mon, 01 Jan 2018 00:00:00 GMT http://hdl.handle.net/10985/13274 2018-01-01T00:00:00Z FABBRO, Rémy PEYRE, Patrice COSTE, Frédéric GUNENTHIRAM, V DAL, Morgan SCHNEIDER, Matthieu The authors propose an analysis of the effect of various operating parameters on the keyhole depth during laser welding. The authors have developed a model that uses the analysis of the thermal field obtained in 2D geometry, which is mainly defined by the characteristic Peclet number. This allows us to show that the dependence of the aspect ratio R of the keyhole with the operating parameters of the process is a function of two parameters: a normalized aspect ratio R0, controlled by the incident laser power and the spot diameter, and a characteristic speed V0 related to the process of heat diffusion. The resulting general law R = f (R0, V/V0) appears to be very well verified by different experimental data and allows to define mean thermophysical parameters of the used materials. These data can then be used for keyhole depths prediction for any subsequent operating parameters of the same material. This model also allows us to define precisely a criterion for a keyhole threshold generation. The authors will apply the derived procedure to successfully analyze experiments on materials with very different thermophysical properties (such as steel alloys and copper), with various focal spots, incident laser powers, and welding speeds. http://hdl.handle.net/10985/13281 Experimental analysis of spatter generation and melt-pool behavior during the powder bed laser beam melting process GUNENTHIRAM, V; PEYRE, Patrice; SCHNEIDER, Matthieu; COSTE, Frédéric; FABBRO, Rémy; DAL, Morgan; KOUTIRI, Imade The experimental analysis of spatter formation was carried out on an instrumented SLM set-up allowing the quantification of spatter ejections and possible correlation with melt-pool behavior. Considering nearly similar SLM conditions than those carried out on SLM machines, an increase of large spatters (>80 μm) with volume energy density (VED) was clearly demonstrated on a 316L stainless steel, which was attributed to the recoil pressure applied on the melt-pool by the metal vaporization and the resulting high velocity vapor plume. In a second step, much lower spattering was shown on Al-12Si powder beds than on 316L ones. Fast camera analysis of powder beds indicated that droplet formation was mostly initiated in the powder-bed near the melt-pool interface. On Al-12 Si alloys, such droplets were directly incorporated in the MP without being ejected upwards as spatters like on 316L. Last, it was shown that a strong reduction of spattering was possible even on 316L, with the use of low VED combined with larger spots (≈0.5 mm), allowing to melt sufficiently deep layers in conduction regime and ensure adequate dilution between layers. Mon, 01 Jan 2018 00:00:00 GMT http://hdl.handle.net/10985/13281 2018-01-01T00:00:00Z GUNENTHIRAM, V PEYRE, Patrice SCHNEIDER, Matthieu COSTE, Frédéric FABBRO, Rémy DAL, Morgan KOUTIRI, Imade The experimental analysis of spatter formation was carried out on an instrumented SLM set-up allowing the quantification of spatter ejections and possible correlation with melt-pool behavior. Considering nearly similar SLM conditions than those carried out on SLM machines, an increase of large spatters (>80 μm) with volume energy density (VED) was clearly demonstrated on a 316L stainless steel, which was attributed to the recoil pressure applied on the melt-pool by the metal vaporization and the resulting high velocity vapor plume. In a second step, much lower spattering was shown on Al-12Si powder beds than on 316L ones. Fast camera analysis of powder beds indicated that droplet formation was mostly initiated in the powder-bed near the melt-pool interface. On Al-12 Si alloys, such droplets were directly incorporated in the MP without being ejected upwards as spatters like on 316L. Last, it was shown that a strong reduction of spattering was possible even on 316L, with the use of low VED combined with larger spots (≈0.5 mm), allowing to melt sufficiently deep layers in conduction regime and ensure adequate dilution between layers.