镍基高温合金选区激光熔化过程温度场研究

Study on the Temperature Field of Nickel-based High-temperature Superalloy in Selective Laser Melting Process

以GH4169镍基高温合金为研究材料,采用ANSYS有限元软件对不同激光功率和扫描速度条件下选区激光熔化(SLM)成形过程温度场变化及热循环过程进行了数值模拟研究,系统分析并揭示了SLM温度场演变机制及其对最终制件性能的影响。研究结果表明:SLM成形过程中粉末床模型各单元均要经历急热急冷的温度循环,而且循环曲线由一个较大温度波峰和若干个较小温度波峰组成;合理的激光功率和扫描速度设定有利于合金粉末的充分熔化以及道间和层间的熔合;激光功率过低或扫描速度过快,会导致热源中心温度过低,合金粉末无法充分熔化,造成成形缺陷;激光功率过高或扫描速度过慢,会导致热源中心温度过高以及粉末床温度梯度较大,易引起合金粉末的过热、飞溅和碳化,最终制件的翘曲变形等。

Taking GH4169 Nickel-based high-temperature superalloy as the research material,the numerical simulation of temperature field and thermal cycle in selective laser melting(SLM)forming process under different laser power and scanning speed is carried out by ANSYS finite element software.The evolution mechanism of SLM temperature field and its influence on the properties of final parts are systematically analyzed and revealed.The results show that each unit of the powder bed goes through the temperature cycle of rapid heating and rapid cooling during the SLM forming process,and the cycle curve consists of one large temperature crest and several small temperature peaks;reasonable setting of laser power and scanning speed is conducive to full melting and interchannel and interlayer fusion of alloy powder;too low laser power or too fast scanning speed will lead to too low heat source temperature,alloy powder can not be fully melted,resulting in forming defects;the laser power is too high or the scanning speed is too slow,will lead to the heat source center temperature is too high and the powder bed temperature gradient is large,easy to cause the alloy powder overheating,splashing and carbonization,the final parts warping deformation.