非稳态温度效应对激光熔凝蠕墨铸铁控形和控性影响的研究  

Study on Influence of Unsteady Temperature Effect on Shape-control and Performance-control of Laser Melting Vermicular Graphite Cast Iron

作　　者：庞铭 刘全秀 浮艺旋 初飞雪[1] PANG Ming;LIU Quanxiu;FU Yixuan;CHU Feixue(Airport College,Civil Aviation University of China,Tianjin 300300,China)

机构地区：[1]中国民航大学机场学院,天津300300

出　　处：《热加工工艺》2020年第22期98-102,106,共6页Hot Working Technology

基　　金：国家自然科学基金项目(U1633111,51206179);中央高校基本科研业务费项目中国民航大学专项资助项目(3122018D020);中国民航大学蓝天青年科研资金资助项目(2018.3-2022.3)。

摘　　要：采用额定功率为3kW的Nd∶YAG激光器开展激光熔凝蠕墨铸铁实验。利用光学显微镜和硬度仪记录分析激光熔凝过程的非稳态温度效应对熔凝层深度、石墨分布及其硬度分布的影响。结果表明:沿激光扫描方向,前面熔凝过程对后面熔凝过程预热的非稳态温度效应对熔凝层深度的影响,取决于预热的非稳态温度效应形成的温度是否达到材料的熔点临界温度;激光能量输入大小影响熔凝层表面的鱼鳞纹大小和分布,在激光扫描速度为2 mm/s、激光功率为1100 W时,在熔凝层正面基本观察不到鱼鳞纹;在激光输入总能量不能达到熔池石墨完全消失的能量临界值时,伴随激光扫描速度的降低和激光功率的升高,熔凝区域石墨数量和面积降低,熔凝区域的残留奥氏体含量增加;由于激光熔凝过程的非稳态温度效应,前面熔凝过程的预热作用对后面熔凝熔池中碳元素含量和分布等的综合影响,在激光扫描速度为1.5 mm/s、激光功率为500 W时,硬度逐渐上升;在激光扫描速度为4 mm/s、激光功率为1100 W时,在扫描收尾区域硬度波动幅度降低。The laser melting vermicular graphite cast iron experiment was carried out by using a Nd:YAG laser with a rated power of 3 kW.The law of influence of the depth,graphite distribution and hardness distribution of the melting layer were determined by optical microscope and hardness meter.The results indicate that along the direction of the laser scanning,the influence of the unsteady temperature of the front melting process on the preheating of the subsequent melting process on the depth of the melting layer depends on whether the temperature formed by the unsteady temperature effect of the preheating reaching the melting point critical temperature effect of the material.The size and distribution of fish scales on the surface of the melted layer were affected by the laser energy input.When the laser scanning speed is 2 mm/s and the laser power is 1100 W,fish scales weren’t observed on the front of the melted layer.When the total energy input by the laser cannot reach the energy threshold at which the molten graphite completely disappears,with the decrease of laser scanning speed and the increase of the laser power,the amount and area of graphite in the molten region decreases and the retained austenite content in the molten region increases.Due to the unsteady temperature effect of the laser melting process,the carbon contents and distribution in the molten pool of the subsequent melting are affected by the front melting preheating process.When the laser scanning speed is1.5 mm/s and the laser power is 500 W,the hardness gradually increases.When the laser scanning speed is 4 mm/s and the laser power is 1100 W,the amplitude o f hardness fluctuatiing decreases in the scanning finishing region.

关 键 词：激光熔凝 蠕墨铸铁 宏观形貌 非稳态温度效应 硬度 

分 类 号：TG174.44[金属学及工艺—金属表面处理]