Book excerpt: Nickel-titanium (Ni-Ti) alloy, or Nitinol, is one of the most used alloys that exhibits a Shape Memory Effect and is used in many industries such as aerospace, automotive, biomedicine, etc. However, its potential is currently limited by its inability to produce complex NiTi parts, due to NiTi's extreme difficulty in machining, making the use of conventional manufacturing processes complicated. In addition, processing of NiTi is highly sensitive to compositional and thermal changes, affecting the final phase structure and, consequently, the martensitic transition temperature of the materials. Additive manufacturing (AM) is a technique for fabricating complex metallic components directly from near-net shapes. By utilizing the AM processing principle, the machinability issues with NiTi can be removed. Additionally, AM allows for the production of 3D geometries that are not possible with traditional methods. A reliable computational model for metal additive manufacturing will improve part quality and lead to component performance. It's important to simulate the additive manufacturing process to optimize design, reduce material waste and ensure the structural integrity of printed objects. In this work, a part-scale simulation study on the effects of bi-directional scanning patterns (BDSP) on residual stress and distortion formation in additively manufactured NiTi parts is presented. The numerical method utilized is based on a modified inherent strain method. The findings from the study provide insights towards understanding the evolution and distribution of residual stresses and distortions developed in the rectangular part. Additionally, these Laser Powder Bed Fusion (LPBF) products have mechanical characteristics that are typically comparable with those of parts produced conventionally. The quality and mechanical characteristics of AM parts can be greatly impacted by defects including keyholing, lack of fusion, and balling. Single bead and thermal history simulation were used to determine the melt pool geometry and temperature distribution in powder bed. The aim of this work is to study the effect of process parameters, such as: laser power, scan speed and layer thickness on the temperature field and melt pool geometry and characteristics of single melting track in a LPBF process by using the Ansys additive simulation software.