Material characteristics of 3-D printed steel

Additive manufacturing of metals is a technology where metal parts are built layer by layer from a 3D model. To do this a heat source is used to melt metal powder or metal rods. There is a large selection of processes that uses different materials and layer deposition techniques. As metal additive manufacturing is a growing field, it is important to understand the different processes and the properties of the metal additive manufactured components. This thesis provides an overview of the most common steel AM processes, process parameters, advantages and disadvantages of the processes and post process treatments, along with the processing challenges with void formation, gas porosity, lack of fusion, residual stresses, cracks and microstructural heterogeneity of the metal additive manufactured parts. Special attention is paid to the fatigue performance of the metal AM parts. To accomplish this, a review of previous research was undertaken. The mechanical properties of as-sintered 17-4 PH stainless steel specimens manufactured by a bound metal deposition process are also studied, and a brief evaluation with the optical light microscope is performed. Mechanical properties of the specimens such as yield strength, ultimate strength, ductility, and modulus of elasticity are obtained by performing tensile tests. Tensile test results from this study show that the building orientation of the specimens relative to the applied loading direction as well as the support structures affects the tensile behavior of the material. Un-melted regions were observed with the optical light microscope