The effect of powder size on laser direct deposition of 410L stainless steel

• Main Author: Jiang, Zhuheng
• Other Authors: Zhou Wei
• Format: Thesis-Master by Coursework
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Mechanical engineering::Prototyping
• Online Access: https://hdl.handle.net/10356/158838
• Institution: Nanyang Technological University

Additive Manufacturing (AM) has been quickly developed in recent years and has many advantages compared to the traditional manufacturing. Direct energy deposition (DED) is a kind of AM which melts powders with laser to build the part layer by layer. Therefore, the characteristics of the powders have great influence on the printing product. This dissertation study the effect of effect of powder size on direct energy deposition of 410L stainless steel. Two ranges of sizes of 410L stainless steel are applied. The smaller size of powder is 15-45 μm while the larger size of powder is 45~125 μm. Two powders were printed on the A36 substrate with same processing parameters. The morphology, microstructure and the microhardness were investigated. The results show that the tracks of smaller powders better surface finish than larger powder. And the processing parameters have great influence on the size of deposition zone. If the laser power increase, the height of deposition zone will decrease while the width will increase. If the powder feeding speed increases, the height will increase significantly while the width of deposition zone will fluctuate slightly. If scanning speed increases the height will increase and the width will decrease. During the DED process, the microstructure of HAZ changed from ferrite and pearlite to lath martensite. HAZ is the hardest zone of cross-section. The microhardness of deposition zone of the larger powders is bigger than that of smaller value. The microhardness of the HAZ of the two sizes of powder is similar.