**1.1 Additive manufacturing processes**

Selection of an appropriate process is very important among the AM processes for successful fabrication. Generally, there are number of different methods available in standard to meet the AM processes and they are listed below.


To start with Binder jetting, it actually uses a 3D printer head and moves in three standard coordinates (x, y, and z axes) to print all the layers of powder material and also a liquid form one known as the binder for adhesive purposes. DED shall be employed with almost entire materials including metals, ceramics, and polymers irrespective of the weight of material for the fabrication of final components. Electric arc, laser, and electron beam shall be used for the melting of solid wire material or feedstock filaments or metal powder to deposit the melted material as layers. Wire Arc Additive Manufacturing (WAAM) is one of an arc welding based AM. Material extrusion involves the spooled polymers which may be extruded or drawn into a heated nozzle. This also builds melted material in the form of layer over a layer and finally, these layers stick either because of temperature control or chemical bonding. Powder bed fusion technology generally involves the formation of melts or partially melts layers of material cleaned by blasting away the excess powder. Many AM techniques follow this concept includes Direct Metal Laser Melting (DMLM), Direct Metal Laser Sintering (DMLS), Electron Beam Melting (EBM), Selective Laser Sintering (SLS), and Selective Heat Sintering (SHS).

### *Welding Based Additive Manufacturing: Fundamentals DOI: http://dx.doi.org/10.5772/intechopen.104768*

Thin sheets of material are laminated over one another together to fabricate a single 3D component is known as simply the sheet lamination. Laminated Object Manufacturing (LOM) and Ultrasonic Additive Manufacturing (UAM) are available technologies for sheet lamination. Vat polymerization customs a liquid resin photopolymer vat to produce a piece [3]. Layers of materials are cured by ultraviolet light by mirrors is called photopolymerization.

Even though the above-listed processes are available for AM, these processes would fall under any one type of technology from three technologies. The first technology is called *sintering* in which the powder form of material used for the fabrication is heated up to the stage well before liquefied for the creation of complex high-resolution components. The second one involves in complete *melting* in which the powder material used for the fabrication is fully melted for the creation of the part. Generally, the laser is used for the action of this melting here. The another third type of technology is referred to as *stereolithography*, in which a process of photopolymerization is employed, therefore, an ultraviolet laser is fired and directed to photopolymer resin to make torque-resistant parts that endure temperatures at both extremes [4]. These processes and technologies are used for the successful 3D printing of components of various materials.

In general, the powder-based additive manufacturing process is so familiar and commercially readily available in most of the nearby industries that fabricate the components that are smaller in size. Our matter of interest WAAM is the wire-based welding process that has emerged to date as a potential candidate for comparatively large AM metal components. The chapter provides the description on WAAM technology and its possible classification while focusing on stainless steel and various synonyms of WAAM being used worldwide have been presented. Various arc-based welding processes have been discussed and a case of stainless steel plate fabrication is given in detail. Various weld defects in WAAM fabrication are presented and a few of the future works while focusing on the fabrication of stainless steel components are presented.
