水冷双气道激光成形侧向送粉喷嘴特性研究

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

采用水冷双气道激光成形侧向送粉喷嘴研究出粉口离熔池工作高度、外部雾化气流对粉末利用率和熔池中心氧含量的影响,载粉气流量与熔池中心氧含量关系及外部雾化气流对熔池中心氧含量的影响,外部雾化气流对CH化合物包覆304不锈钢激光成形试样氧化夹渣与力学性能的影响。结果表明,随出粉口离熔池中心高度的增加,粉末利用率逐渐降低,氧含量逐渐增大;仅有载粉气流量1~12 L/min时,氧含量为3.92%~5.48%;当载粉气流量1~12 L/min、外部雾化气流1~5 L/min时,氧含量为1.40%~2.68%;激光成形试样内部夹渣明显减少且表面呈金属光泽,其抗拉强度、断后伸长率比单气道送粉喷嘴制备的试样分别提高7.8%和23.1%。

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 powder-carrying 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 was 1~12 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.