ABSTRACT
Additive Manufacturing is progressively increasing its footprint in several applications from aerospace to medical and from automotive to power generation. First components, fully manufactured by 3D printing technologies are already installed in real equipment (i.e. gas turbines) and are accumulating service experience. Yet the characterization in corrosion environments has not been fully investigated and the limited available literature and testing experience, in addition to lack of process standardization, is delaying the oil companies in exploring the potentials of this innovative manufacturing process for oil & gas applications. Additive manufacturing offers advantages in overcoming shape complexity manufacturing issues and allows the design engineers to think out of the boundaries historically determined by conventional machining of production processes. This work will concentrate on precipitation hardening alloy 718 (UNS(1) N07718) produced by laser powder bed technology, exploring the influence of building parameters on corrosion performances in chloride-containing and sour solutions, also compared to wrought alloy baseline. Specimens in different building direction and final heat treatment will be compared in their mechanical properties and microstructure versus electrochemical and stress corrosion cracking behavior. The main scope of this work is to explore different process configurations to understand the corrosion response of additive manufactured alloys and to suggest the parameters to be controlled for future qualification in sour environment.
INTRODUCTION
Additive Manufacturing (AM) is the process of producing parts through the successive layering of material rather than the removal of material, which is the case with conventional machining.
AM can create complex geometries without the use of any sort of tools, molds or fixtures, largely reducing wasted material. Instead of machining components from solid billets of metal, much of which is cut away and discarded, the only material used in AM is what's required to shape the part.
The geometrical freedom of AM technologies allows a part to be engineered as the designer envisions it, without traditional manufacturing constraints. This can translate to extremely lightweight designs or reduced part counts. With very high material utilization and without the need to stock expensive castings or forgings (only powders of different raw materials have to be stocked), it is a highly cost effective, energy efficient and environmentally friendly manufacturing process.
