Research On Stress Evolution Mechanism And Control Of Laser Deposition Manufacturing

Laser Deposition Manufacturing Technology is an advanced manufacturing technology which is based on Laser Cladding and Rapid Prototyping technology. It makes 3D metal parts from CAD models rapidly directly without making semi-finished product, and has been widely applied to advanced equipment manufacturing and research. During the laser deposition manufacturing process, the parts exist complicated residual stress and deformation for metal heat transfer and thermal- elastoplastic, and it badly affects the quality of the parts.Therefore, this article carry on a systematical research on the stress evolution and control of laser deposition manufacturing of BT20 titanium alloy, which provides theoretical basis for the removing or reducing the residual stress and deformation.A mathematical model which is based on finite element theory is built of the temperature field and residual stress field of laser deposition manufacturing process by using ANSYS Parameter Design Language. This article mainly study the effects of the temperature field and residual stress field under different process parameters of laser deposition manufacturing.At the same time, the effect of scanning methods on temperature and residual stress field are investigated by numerically. The distribution of temperature field, the performance of node thermal cycle, the node temperature gradient and surface residual stress are analyzed comparatively under separate area scanning and sequential area scanning methods. In order to check up the correction of the mathematic model, the temperature field, the surface residual stress under different scanning paths are measured by non-contact infrared temperature measurement system and indentation strain-gage residual stress tester, respectively. The distortion profile of substrate under different scanning paths is also researched. The results indicated that the performance of node thermal cycle, the node temperature gradient are similar, but the thermal accumulation of parts decreases, the temperature distribution is uniform, the node temperature gradient is reduced greatly, the stress concentration distributing is ameliorated and the residual stress is reduced on the surface by the short raster separate area scanning. Lastly, discussing the methods for reducing or removing residual stress.