Control of shape and performance for direct laser fabrication of precision large-scale metal parts with 316L Stainless Steel

Direct laser fabrication (DLF) is a rising rapid prototyping manufacturing technology, which can directly build full-density and high-performance complex metal parts from CAD solid model without using any molds and tools. This paper presents an investigation on the control of shape and performance for the precision large-scale metal parts with 316L Stainless Steel by DLF technology. The influence of the processing methods and parameters on the part was studied by a batch of cuboid metal samples. The results show that a precision cuboid metal sample with a uniform surface can be obtained at a small laser scanning spot and a higher laser scanning velocity. Especially, the as-DLFed cuboid metal sample of 316L Stainless Steel exhibits a uniform microstructure and evident refined crystalline grain as well as its superior properties of ultimate strength (UTS) and yield strength (σ0.2), even compared with that at a lower laser scanning velocity. Based on the optimal processing methods and parameters, lastly, a large-scale metal part of 316L Stainless Steel with a high dimensional accuracy and a uniform surface was successfully fabricated by DLF at a laser scanning velocity of 1400 mm/min. The measurement results show that the shape precision of the part is quite good, and the actual build size of the sample is 615.30 mm×216.50 mm×232.50 mm while the designed value is 615.54 mm×216.48 mm×235.69 mm.

► An acceptable method to fabricate a precision large-scale metal part is proposed.
► The variational-orientation raster scanning is a better laser scanning pattern.
► The as-fabricated metal samples have a good shape quality and performance.
► An accurate large-scale metal part is fabricated by direct laser fabrication.