Metal additive manufacturing

as a nearnet forming process that directly prints raw materials such as metals into products

has extremely high application value in aerospace

automotive and shipbuilding

micro-nano manufacturing

biomedical engineering and other fields. Its special layer-by-layer printing mechanism makes the manufacturing process defect prone to be large

which may cause many problems such as density difference

anisotropy

local deformation and stress concentration.Therefore

reasonable and efficient non-destructive testing methods are needed for defect detection and quality inspection. In this paper

three methods of ultrasonic

radiography and visual inspection are taken as the main objects. By analyzing their principles

typical application scenarios

advantages and limit-ations

the applicable scenarios and development trends of non-destructive testing in metal additive manufacturing are summarized

and the development direction of intelligent detection and control in metal additive manufacturing is proposed.