Temperature field control method in laser additive manufacturing process

The invention relates to the field of metal component additive manufacturing, in particular to a temperature field control method in the laser additive manufacturing process. The method comprises the following steps that firstly, metal powder for the impeller and heterogeneous nucleation refiner powder are mixed; secondly, slicing software is used for conducting slicing and scanning path area discretization planning on the digital model of the impeller component to be formed; thirdly, laser energy input is changed into discontinuous input according to a planned scanning path; and fourthly, laser additive manufacturing is conducted. In-situ preheating and resistance tape or resistance wire heating in the laser additive manufacturing process are combined together, heat preservation is conducted through heat preservation sand or heat preservation cotton, the temperature gradient in a component to be manufactured or remanufactured can be reduced, residual stress can be reduced, and regulation and control over the microstructure of a formed part can be achieved by controlling the heating temperature. The method is high in applicability, not only can be used for additive manufacturing of the metal component, but also can be used for repairing and remanufacturing of the metal component.