When reporting surface quality, the roughest surface is a reference for the measurements. In LPBF due to recoil pressure and scan movement, asymmetric surface is shaped, and surface roughness has different values in different measurement orientations. In this research, the influence of the laser powder bed fusion (LPBF) process parameters on surface tension and roughness of Ti-6AI-4 V parts in three orientations are investigated. To improve the mechanical properties, heat treatment was carried out and added to the designed matrix to generate a comprehensive data set. Taguchi design of experiment was employed to print 25 samples with five process parameters and post-processing. The effect and interaction of the parameters on the formation of surface profile comprising tension, morphology and roughness in various directions have been analysed. The main contribution of this paper is developing a model to approximate the melting pool temperature and surface tension based on the process parameters. Other contributions are an analysis of process parameters to determine the formation and variation of surface tension and roughness and explain the governing mechanisms through rheological phenomena. Results showed that the main driving factors in the variation of surface tension and formation of the surface profile are thermophysical properties of the feedstock, rheology and the temperature of the melting pool. Also, the results showed that while the value of surface tension is the same for each test case, morphology and the value of roughness are different when analysing the surface in perpendicular, parallel and angled directions to laser movement.

报告表面质量时，最粗糙的表面是测量的参考。在LPBF中，由于后坐力和扫描运动的影响，非对称表面被成形，并且在不同的测量方向上，表面粗糙度具有不同的值。在这项研究中，研究了激光粉末床熔合（LPBF）工艺参数对Ti-6AI-4 V零件在三个方向上的表面张力和粗糙度的影响。为了改善机械性能，进行了热处理并将其添加到设计的矩阵中以生成一个综合的数据集。Taguchi设计的实验用于打印25个具有五个过程参数的样品并进行后处理。已经分析了参数对包括不同方向上的张力，形态和粗糙度的表面轮廓的形成的影响和相互作用。本文的主要贡献是建立了一个基于工艺参数来估算熔池温度和表面张力的模型。其他贡献是对工艺参数的分析，以确定表面张力和粗糙度的形成和变化，并通过流变现象解释了控制机理。结果表明，改变表面张力和形成表面轮廓的主要驱动因素是原料的热物理性质，流变学和熔池温度。同样，结果表明，尽管每个测试用例的表面张力值相同，但在垂直，平行和成角度的方向分析激光运动表面时，形貌和粗糙度值却不同。