Application of ultrasonic peening during DMLS production of 316L stainless steel and its effect on material behavior

Abstract

Purpose Additive manufacturing (AM) processes involve a layer-by-layer sintering of metallic powders to produce fully functional three-dimensional parts. This layer-by-layer building process provides a unique opportunity to enhance mechanical properties by applying treatments that previously were possible only on the surface in traditional manufacturing techniques. The purpose of the study is to examine the effect of ultrasonic peening (UP) applied during a layer-by-layer direct metal laser sintering (DMLS) fabrication of 316L stainless steel on its mechanical properties and microstructure. Design/methodology/approach Uniaxial tensile tests were performed at 1.27 mm/s to determine the effect of UP treatment on the average global behavior of a 316L part, whereas hardness measurements using nanoindentation were performed to determine the modification of local mechanical properties. Compressive buckling tests at a loading rate of 3 mm/min were performed on sample coupons with a large aspect ratio to evaluate the effect of UP on any potential delamination of DMLS layers. Techniques such as optical and scanning electron microscopy (SEM) imaging were utilized to determine the effect of UP on the microstructure. Findings Overall, significant modification in mechanical properties such as hardness and yield strength, along with microstructure, was observed. Large increases in both the average global and local mechanical properties, as well as a disruption in the columnar grain microstructure, was observed in DMLS parts treated with UP treatment. Originality/value Results indicate an opportunity for UP to be used as an in-situ process during AM processes for dynamically altering the mechanical behavior, microstructure, and distortion due to residual stress formation, in a tunable fashion.

Directed Energy Deposition of AISI 316L Stainless Steel Powder: Effect of Process Parameters

“…For the sake of comparison, the tensile properties obtained in the present study are also compared with other literature data. It can be seen that the UTS values are in line with those obtained in other works and that slightly lower YS were obtained [38]. The comparison with the tensile properties of 316L processed by conventional routes highlights that, as expected, LP-DED samples have higher YS, lower elongation, and similar UTS.…”

Manufacturing of high-precision surface micro-structures on stainless steel by ultrasonic impact peening

“…the yield stress of DMLS 316L stainless steel treated by UIP is 37% higher than untreated one [47]. Therefore, the friction coefficient for UIP is larger than that for UEVC, due to more pronounced residual stress formed.…”

Surface Shot Peening Post-processing of Inconel 718 Alloy Parts Printed by Laser Powder Bed Fusion Additive Manufacturing

“…The type of mechanical or chemical post-processing used to improve surface texture/microrelief depends on the required surface roughness and geometric complexity of components. Recently, various methods of surface finishing and hardening, such as a shot peening or sandblasting , ultrasonic peening or ultrasonic nanocrystal surface modification (Ref [9][10][11][12], laser shock peening (Ref 13,14), cavitation peening (Ref 15,16), barrel finishing (Ref8, 17,18), vibratory finishing (Ref 19), machining (Ref 19), electrochemical polishing (Ref 20), etc., were used to enhance the surface properties in the 3D printed parts.…”