基于环形光光内送粉激光熔覆温度场的数值模拟

Temperature Field Numerical Simulation of Laser Cladding Based on Internal Powder Feeding through a Hollow Laser Beam

针对"光束中空,光内送粉"的激光熔覆工艺方法,利用Ansys软件的参数化设计语言(APDL)建立了环形激光光斑连续移动加载的激光熔覆模型。通过计算该模型,可以掌握环形激光光内送粉激光熔覆过程中温度场的分布规律。计算结果表明,采用环形激光束加载时,熔池的最高温度区域的形状呈现出"马鞍形"。在基体纵切面上,熔池的高温区域分布呈不对称的"W"形,且高温区域主要分布在光斑中心往后;在基体横截面上,熔池的高温区域分布呈对称的"W"形,熔池中心温度低,两侧温度高,通过基体横断面等温线的分布能够判断熔覆层与基体的结合情况。位于扫描路径中心位置的点在激光束扫过其过程中会经历迅速升温、降温、升温、再迅速降温的急冷急热过程,且第二次升温高于第一次的温度值;位于光斑内外环之间的点在激光束扫过其过程中只有一次升温降温的过程,温度分布较均匀。

A numerical simulation model of laser cladding based on internal powder feeding through a hollow laser beam is set up by Ansys parametric design language（APDL）.The laser beam of cladding is a continuous motion ring form according to the process method of ＂hollow laser beam and internal powder feeding＂.Temperature distribution of laser cladding process can be got by model calculation.The calculation results show that,when the hollow laser beam is used,the highest temperature area of the molten pool is the saddle-shaped.In the base plate longitudinal section,the distribution of molten pool high temperature is asymmetrical ＂W＂ shape,and high temperature area mainly distributes behind the flare center.In base plate cross section,the distribution of molten pool high temperature is symmetrical ＂W＂ shape,the temperature of the molten pool center is low,and the both side temperature of the molten pool is high,thus the combination between cladding layer and base plate can be judged by the isothermal diagram.The temperature in the center of laser scanning undergoes twice sharp quenching and snap heat processes.It goes up and down rapidly first,and then goes up and down again.The second rising temperature is higher than the first one during the scanning.The temperature on both edges of the scanning tracks has only once sharp quenching and snap heat process,and the distribution of temperature is more uniform.