Microstructural and thermal expansion behaviour of graphene reinforced 316L stainless steel matrix composite prepared via powder bed fusion additive manufacturing

Abstract

316 L Stainless steel is widely used industrial material having application in broad range of domain including automotive, structural as well as biomedical. It is also used for several high temperature applications in various industries, permanent deformation due to thermal cycling and continuous high temperature exposure is one of the major concern in industries. Therefore, enticing thermo physical properties is very crucial for better efficiency and service life of components. In the present work, graphene reinforced 316 L metal matrix composite was prepared via powder bed fusion additive manufacturing technique in order to make it more stable material at elevated temperature. Powder bed fusion technique was used to melt graphene coated 316 L metal powder layer by layer to prevent agglomeration of graphene inside the matrix. To identify the chemical state of the elements in the prepared composite, synchrotron based X-ray photoelectron spectroscopy was performed. However, no carbide formation was observed inside the matrix and the prepared composite was purely austenitic. The obtained composite with 0.2 wt % graphene has coefficient of thermal expansion (CTE) equal to 19.3 × 10−6 K-1 which is about 6.2% lower than bare 316 L at 1100 °C. The value further decrease after annealing process and this much decrement in CTE can increase the application window of the material to the large extent.

Keywords

• Graphene
• Powder bed fusion
• Coefficient of thermal expansion
• Composite