Crack restriction mechanism of thin wall metal parts fabricated by laser direct deposition shaping

In order to restrict the generation and propagation of cracks in thin wall metal parts fabricated by laser direct deposition shaping method, using 'element birth and death' technique, a three-dimensional multitrack and multilayer thin wall model was developed, and the deposition process was simulated. Different scanning methods, including long edge parallel reciprocating scanning, short edge parallel reciprocating scanning and interlayer orthogonal parallel reciprocating scanning, were introduced. The effects of different substrate preheating temperatures were also researched. The von Mises equivalent stress and its X-, Y- and Z-directional principal stresses were analysed in detail. Under the same conditions used in the simulations, the deposition experiments were conducted, and the crack generation and restriction mechanism of thin wall metal parts were further discussed.