丝材+电弧增材制造(wire and arc additive manufacturing,WAAM)适用于一体化成形大型复杂结构组件,在保证高氮钢增材结构件性能的同时,进一步提升高氮钢丝材的沉积速率,需要对不同直径高氮钢丝材的等离子弧增材工艺特性进行研究.通过设计不同的送丝高度和送丝速度对高氮钢增材过程中的飞溅行为,及焊道N元素含量的变化进行研究,分析等离子弧增材制造中HNS6-N5高氮钢丝材的熔化特性和飞溅过程.结果表明,送丝速度和送丝高度决定了高氮钢熔滴的过渡模式,也影响了焊道成形与工艺稳定性.在相同的热输入下,随着送丝速度的减小,熔滴的飞溅行为更加剧烈,同时焊缝中的N元素含量呈现下降趋势,随着送丝速度的增加,焊缝中的N元素含量逐渐增加,综合调节丝材直径、送丝速度与送丝高度可以获得过程稳定、熔滴过渡飞溅、焊缝氮含量高、熔覆效率高的增材效果.
Transformation characteristics of high-nitrogen steel droplets based on PTA process
Wire and arc additive manufacturing(WAAM)using high-nitrogen steel is suitable for the integrated forming of large and complex structural components.In order to improve the deposition rate of high-nitrogen steel wire while ensuring the performance of additively manufactured components,it is necessary to study the plasma arc additive manufacturing characteristics of different diameters of high-nitrogen steel wire.The melting characteristics and spatter process of HNS6-N5 high-nitrogen steel wire in plasma arc additive manufacturing were analyzed.The study investigated the spatter behavior and N element content in weld metal during the additive manufacturing of high-nitrogen steel by designing different wire feed heights and feed speeds.The results show that the wire feed speed and height determine the transitional mode of high-nitrogen steel droplets and also affect the weld bead formation and process stability.Under the same heat input,decreasing the wire feed speed results in more intense spatter behavior of the molten droplets,while the N element content in the weld bead decreases.Increasing the wire feed speed gradually increases the N element content in the weld bead.By comprehensively adjusting the wire diameter,feed speed,and feed height,a stable process with low spatter,high nitrogen content in the weld bead,and high deposition efficiency can be achieved.
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