Wire arc additive manufacturing (WAAM) is a class of technologies suitable for producing large parts due to its high material deposition and building rates. Among the many possible materials processed by WAAM, austenitic stainless steels, e.g. 316L, are commonly employed. The structure of WAAM 316L thin parts has been studied extensively before. However, multiwalled or thick WAAM 316L parts remain largely unexplored. Hence, in this study, the microstructure of a thick 316LSi WAAM part is characterised in detail. The microstructure of the part consists of large and highly-oriented columnar grains dominated by epitaxial and competitive growth. The overlapping regions between neighbouring fusion zones contain long grains with a dominant <100> texture, which cross several layers and are aligned with the building direction. The grains' internal microstructure consists of an austenite matrix, ferrite with locally varying dendritic morphologies and dispersed oxide inclusions. The texture spatially varies across the part, and this variation is correlated to the local thermal gradient induced by the building strategy and processing conditions used during the manufacturing of the thick-walled part.
Bibliographical noteFunding Information:
This research was carried out under project number P16-46/S17024f, which is part of the Aim2XL program, in the framework of the Partnership Program of the Materials innovation institute M2i ( www.m2i.nl ) and the Netherlands Organization for Scientific Research ( www.nwo.nl ). The research was conducted in collaboration with industrial partners and supported by the Rotterdam Fieldlab Additive Manufacturing BV (RAMLAB) , www.ramlab.com .
- Spatial variations
- Stainless steel
- Wire arc additive manufacturing