Process Study And Profile Prediction On Laser Cladding Of Titanium Alloys

Laser Cladding is a technology based on single-track laser cladding, which eventually form a presetting shape by multi-track and multi-layer accumulation. Currently, with rapid development of Laser Cladding Repair and Laser Solid Forming technology, forming precision requirements of laser cladding become higher and higher. Moreover, process parameters and clad profile of laser cladding both are important factors impacting the forming precision. Therefore the study on them and their relationships have attracted more and more attention. In this background, a series of experiments and theoretical research are conducted, which is starting with single-track laser cladding and aiming at profile prediction and parameters selection. Titanium alloy TC4widely used in aerospace field is the laser cladding material. At the same time, coaxial laser cladding processing system is the laser cladding equipment. And the main contents of this article are shown as follows:Firstly, by a orthogonal experiment of single-track laser cladding, the influence of laser power, scanning speed and feeding rate on shape parameters (width, depth and aspect ratio) is analyzed. Then forming mechanism of single-track bow cross section is studied. In addition, the causes and improvement methods of main defects in TC4laser cladding are discussed.Secondly, through a single factor experiment, the influence of laser defocus amount on single-track clad layer is analyzed. On this basis, by a central composite design (CCD) experiment, a quadratic regression model is established, which can predict single-track clad layer geometry. As well as, a further study on the influence of four process parameters on clad layer profile is conducted.Thirdly, under two overlap ways, single-layer and multi-track laser cladding model diagrams are drew in hot overlap and cold overlap. And the optimal scanning spaces are given accordingly. In this part, different hot overlap situations are discussed with single-track clad in different aspect ratios. In particular, it’s indicated that meeting a certain condition, good multi-track clad layer can also be gotten even when aspect ratio is less than2. Meanwhile, two implementation methods about laser cladding cold overlap are proposed. And on the basis of simple operation and stable forming, an optimal method is selected.Fourthly, based on single-track and multi-layer laser cladding, a geometrical model is constructed. On the basis, a reasonable Z-axis lift amount is derived and a linear relationship between accumulation numbers and clad height is raised. Besides, multi-layer laser cladding experiments in different scanning ways are conducted. As well as, the influence of scanning ways on clad layer morphology is comparatively studied. Generally, prediction model of single-track clad layer and geometrical model of multi-track and multi-layer laser cladding are established in the paper. Thus, with the research achievements, two-dimension morphology of laser cladding layer can be simply predicted and selection principles of process parameters in multi-track and multi-layer laser cladding are provided.