Study of mechanical properties of AISI 316 stainless steel processed by “selective laser melting”, following different manufacturing strategies

Laser powder-bed fusion of Inconel 718 to manufacture turbine blades

“…As regarding LPBF, anisotropy has been discussed in the literature for stainless steel [21,22], titanium [23], and Ni-based alloys [24,25]; anisotropy has also been reported when AM is conducted by means of electron beam [26]. This issue is expected to be crucial for Ni-based superalloys which are highly anisotropic and are conveniently processed to the purpose of producing functionally graded components [27], indeed.…”

“…An approach to measure the degree of AMinduced anisotropy as a function of the direction of building has been proposed in the literature [22]: the normalized yield or ultimate tensile strengths have been evaluated with respect to their counterpart as resulting from an in-plane (i.e., flatbuilt) specimen. Depending on the base metal [21,22,24], normalized strength in LPBF has been found to range from 0.8 to 1.1. The position of building in the working area has even been suggested as possible additional reason of anisotropy [22], although this effect is thought to be negligible when focusing and deflecting are driven by means of an F-theta lenses providing uniform irradiance and approaching speed over the working surface [28].…”

Comparison of Vacuum Sintered and Selective Laser Melted Steel AISI 316L

“…That in summary with part orientation according to the support structure result in strong anisotropy effect in mechanical properties of SLM elements [1,6]. The anisotropy of mechanical properties of additive manufactured stainless steels is low in the Z direction, while in the X and Y axis it can be avoided by using an adapted laser strategy [1]. The key advantage of additive manufactured stainless steels is high part densities up to 99.9% that can be reached and fine microstructures with small residual porosity comparing to classic pressing and sintering method [7].…”

“…The selective laser melting (SLM) of austenitic stainless steel type 316L is extensively studied for a few years, and high mechanical properties, especially in term of yield strength have been proven for SLM part, comparable to booth wrought and cast products made of this alloy [1].…”

“…The formed microstructures relate to the building direction, resulting in elongated grains parallel to the growing directions, having cellular-columnar morphology typical for the rapid cooling rate of high energy source processing technics [4,5]. That in summary with part orientation according to the support structure result in strong anisotropy effect in mechanical properties of SLM elements [1,6]. The anisotropy of mechanical properties of additive manufactured stainless steels is low in the Z direction, while in the X and Y axis it can be avoided by using an adapted laser strategy [1].…”