Research teams from Waseda University’s School of Science and Engineering and the School of Mechanical Engineering and Materials Science of the University of Pittsburgh have developed a method that can reduce stress in metal parts for laser powder bed melting processes.
Laser powder bed melting process is a metal 3D printing technology, which belongs to the lamination molding process. When printing, use laser to melt and solidify a layer of metal powder, then lay a layer of metal powder, and then continue to melt and solidify the metal powder with laser to repeat this process to form a three-dimensional structure.
The melting and solidification area will produce a large shrinkage residual stress, which will lead to warping and deformation of metal parts.
Research team found that the shrinkage residual stress is larger in the scanning direction of the laser, and the shrinkage residual stress is smaller in the vertical direction of the laser. Therefore, the researchers optimized the part structure to form a hollow structure in the best way, that is, the lattice structure. The possibility of deformation of metal 3D printed parts is successfully reduced by optimum laser path forming.
Under the premise of optimization, we developed a simple intrinsic strain method, which is expressed in formulas, and uses the topology optimization algorithm to best determine the distribution of the lattice and the laser scanning direction to reduce shrinkage residual stress.
Through this lattice structure, the local stress state of the molded product can be optimized, which can reduce the possibility of warping and deformation. Promising to be used in large structures (which are greatly affected by thermal deformation).
