316L Stainless Steel Powders for Additive Manufacturing: Relationships of Powder Rheology, Size, Size Distribution to Part Properties

Strength Enhancement of Laser Powder Bed Fusion 316L by Addition of Nano TiC Particles

316L stainless steel is widely used in various industrial fields, but its strength is relatively low. The improvement of its strength has become a research hotspot. In this study, nano titanium carbide (TiC) particles are ball milled with 316L with the addition of 2 wt% and 4 wt%. The composite powder was then used for the fabrication of samples by laser powder bed fusion. The results show that the TiC is uniformly distributed in the microstructure. With the addition of TiC, the average size of the grains is significantly reduced. The strength, hardness, and wear resistance of TiC/316L samples have been greatly improved. The tensile strength of formed 2 wt% TiC/316L is 948 MPa, together with a extension rate of 36.0%, which has been increased by 42.6% and 79.7%, respectively. This study provides an effective way to improve the strength at room temperature and the high temperature of 316L built by laser powder bed fusion.

A Critical Review on Effect of Process Parameters on Mechanical and Microstructural Properties of Powder-Bed Fusion Additive Manufacturing of SS316L

Additive manufacturing (AM) is one of the recently studied research areas, due to its ability to eliminate different subtractive manufacturing limitations, such as difficultly in fabricating complex parts, material wastage, and numbers of sequential operations. Laser-powder bed fusion (L-PBF) AM for SS316L is known for complex part production due to layer-by-layer deposition and is extensively used in the aerospace, automobile, and medical sectors. The process parameter selection is crucial for deciding the overall quality of the SS316L build component with L-PBF AM. This review critically elaborates the effect of various input parameters, i.e., laser power, scanning speed, hatch spacing, and layer thickness, on various mechanical properties of AM SS316L, such as tensile strength, hardness, and the effect of porosity, along with the microstructure evolution. The effect of other AM parameters, such as the build orientation, pre-heating temperature, and particle size, on the build properties is also discussed. The scope of this review also concerns the challenges in practical applications of AM SS316L. Hence, the residual stress formation, their influence on the mechanical properties and corrosion behavior of the AM build part for bio implant application is also considered. This review involves a detailed comparison of properties achievable with different AM techniques and various post-processing techniques, such as heat treatment and grain refinement effects on properties. This review would help in selecting suitable process parameters for various human body implants and many different applications. This study would also help to better understand the effect of each process parameter of PBF-AM on the SS316L build part quality.