Possibilities of Evaluating the Quality of Products Produced by Directed Energy Deposition Technology

It is well known that the porosity of a product can have a negative effect on the mechanical properties of the product. For this reason, its control is very important. Porosity can be assessed by two methods - destructive and nondestructive inspection. However, the identification of very small pores is still very difficult for metallic materials, as the pore size may be below the resolution of most commonly used NDT techniques. In addition, different types of pores may be present in a single part, with one type usually dominating. Proper identification of porosity is essential to estimate the impact on structural properties. For pore assessment, as for other defects, the description of the morphology, distribution and frequency is important. This article deals with the comparison of methods designed to determine the porosity of products that have been manufactured using Laser Directed Energy Deposition – L-DED additive process. The samples were made from AISI 316L stainless steel. The porosity of these samples was assessed using destructive and nondestructive methods. Subsequently, their comparison was made in relation to the detection of different pore sizes. The samples were subsequently subjected to the HIP process (Hot Isostatic Pressing). For these samples, the changes that occurred in the material as a result of this process were subsequently quantified. This process should have a positive effect on improving the quality of the product produced by AM technologies, e.g. by reducing the number and size of pores.