Tribological Performance of Additively Manufactured AISI H13 Steel in Different Surface Conditions

Abstract

Additive manufacturing of metallic tribological components offers unprecedented degrees of freedom, but the surface roughness of most as-printed surfaces impedes the direct applicability of such structures, and postprocessing is necessary. Here, the tribological performance of AISI H13 steel samples was studied. These were additively manufactured through laser powder bed fusion (L-PBF), also referred to as selective laser melting (SLM). Samples were tested in four different surface conditions: as-printed, polished, ground and polished, and laser-surface-textured (LST) with round dimples. Friction experiments were conducted in a pin-on-disk fashion against bearing steel disks under lubrication with an additive-free mineral base oil for sliding speeds between 20 and 170 mm/s. Results demonstrated that, among the four surface treatments, grinding and polishing resulted in the lowest friction coefficient, followed by the as-printed state, while both polishing alone and laser-surface texturing increased the friction coefficient. Surprisingly, direct correlation between surface roughness and friction coefficient, i.e., the rougher the surface was, the higher the friction force, was not observed. Wear was minimal in all cases and below what could be detected by gravimetrical means. These results highlight the need for an adequate post-processing treatment of additively manufactured parts that are to be employed in tribological systems.

Post-processing of additively manufactured metallic alloys – A review

“…These requirements are commonly set by specific surface-texture parameter targets, from the most used Ra (and areal Sa) to parameters related to material ratio curve. It was shown that even manually-removed material using coated abrasives (220-1200 mesh), combined with short-time polishing using a diamond slurry, can reduce as-built surface texture of PBF-LB/X40CrMoV5-1 tool steel to mirror-like finish at Sa = 0.15 μm [248]. The as-built layer (30 μm thick) here could not be removed by polishing alone, but the combined abrasive post-processing lowered the friction coefficient by about one order of magnitude (i.e., from 0.1 for as-built to 0.01 of finished sample).…”

Wear Analysis of Additively Manufactured Slipper-Retainer in the Axial Piston Pump

“…The test part (shown in Figure 2) was designed using CAD software (SolidWorks 2021, version number: 6.30.1030, Dassault Systèmes, Vélizy-Villacoublay, France) and manufactured using the SLM 125HL machine (SLM Solutions AG, Lubeck, Germany). There is also an additional factor that is very important in the case of hydraulic solutions, and at the same time, it is one of the biggest weaknesses of AM-the high surface roughness of the as-built parts [48][49][50][51][52][53][54]. In the case of H13 tool steel, Guenther et al [52] revealed that in the case of such steels, a direct correlation between surface roughness and friction coefficient, i.e., the rougher the surface was, the higher the friction force, does not take place.…”

“…There is also an additional factor that is very important in the case of hydraulic solutions, and at the same time, it is one of the biggest weaknesses of AM—the high surface roughness of the as-built parts [ 48 , 49 , 50 , 51 , 52 , 53 , 54 ]. In the case of H13 tool steel, Guenther et al [ 52 ] revealed that in the case of such steels, a direct correlation between surface roughness and friction coefficient, i.e., the rougher the surface was, the higher the friction force, does not take place.…”

The Influence of Process Parameters on the Low-Cycle Fatigue Properties of 316L Steel Parts Produced by Powder Bed Fusion

“…[1][2][3] Nowadays, it is well known that despite such good research results on the mechanical properties of the AM parts, anisotropy plays an important role in the performance properties, which is especially important in some industrial applications. [4,5] From the point of view of fatigue properties, it is very important to take into account some technologically based issues, such as porosity, [6,7] the increased surface roughness of the as-build parts, [8,9] residual stresses, [10,11] or the influence of build orientation during the process. [12,13] The phenomenon related to the occurrence of lower fatigue strength of AM parts could be compensated by adjusting the geometry of the parts to the so-called ''Design for Additive Manufacturing.''…”