Study on characteristics of the double-side feeding nozzle with water cooling for laser forming

A double-side feeding nozzle with water cooling for laser cladding was designed. Effects of the working height between the powder outlet and the molten pool,together with the external protective gas flow on powder utilization and oxygen content in the molten pool were carefully investigated. Influence of the powder-carrying gas flow on oxygen content in the molten pool was explored. Effects of the external protective gas curtain on oxidation,slag inclusion and mechanical properties of hydrocarbon-coated 304 stainless steel specimens by laser cladding were studied. The results indicate that powder utilization gradually decreased and oxygen content in the molten pool increased with the increase of the working height between the powder outlet and the molten pool. Oxygen content in the molten pool was 3. 92% ～ 5. 48% when powdercarrying gas flow was only 1 ～ 12 L/min. Oxygen content in the molten pool decreased to 1. 40% ～ 2. 68% when powder-carrying gas flow was1 ～ 12 L/min and external protective gas flow was 1 ～ 5 L/min. The slag inside the laser forming specimen was significantly reduced and the surface exhibited a metallic luster. The tensile strength and elongation of the specimens were enhanced by 7. 8% and 23. 1% in comparison to those specimens prepared using the single-side feeding nozzle.