1.1　Background

Additive Manufacturing(AM) technology, commonly known as 3D printing, refers to the manufacture of a wide range of geometrically complex geometric parts through the obtained three-dimensional model data.This process involves printing successive layers of the material, which need to be formed layer by layer.This technology was developed by Charles Hull in 1986 in a process known as stereolithography.Subsequent developments included Powder Bed Fusion, fused deposition modeling, inkjet printing, and contouring.AM involves a variety of methods, materials and equipments.After years of development, it has already had a huge impact on manufacturing and logistics processes.AM has been widely used in different industries such as construction, prototype manufacturing and biomechanics.Due to the advantages of waste-reducing, freedom of design and automation, this technology is widely used in aerospace, medical and automotive industries.

Metal additive manufacturing is a process that combines powder metallurgy, solidification, CAD/CAM(Computer Aided Design/Computer Aided Manufacturing), rapid prototyping and other technologies and builds layer by layer.Common metal additive manufacturing technologies include Selective Laser Sintering(SLS), Laser Metal Deposition(LMD), Laser-based Powder Bed Fusion(L-PBF), Electron Beam Melting(EBM), Laser Cladding, Direct Energy Deposition(DED), etc.These processes use thermal energy to melt a polymer, metal, or ceramic material, and these molten materials are deposited and solidified into the desired shape.