“…While in general the texture is characterized by Goss component, {011}<001>, it has also a noticeable orientation spread around BD approximately ±10 • . A further clarification of GOSS-type texture in LPBF microstructure can be found in Bahshwan et al [49]. Since the side view (b) is mapped from the plane of horizontal loading, it is able to indicate the horizontal loading direction in the pole figures in Fig.…”
“…While in general the texture is characterized by Goss component, {011}<001>, it has also a noticeable orientation spread around BD approximately ±10 • . A further clarification of GOSS-type texture in LPBF microstructure can be found in Bahshwan et al [49]. Since the side view (b) is mapped from the plane of horizontal loading, it is able to indicate the horizontal loading direction in the pole figures in Fig.…”
“…The elongated morphology of the grains along the BD reduces the barrier to deformation while sliding along this direction. This can cause a higher rate of wear as compared to the perpendicular surface. − However, it is also worth noting that the corrosion wear of the two surfaces is similar due to similar corrosion rates. Therefore, the marginal differences in the wear rates can be assumed to arise primarily from the differences in the mechanical properties of the two surfaces.…”
Additive manufacturing (AM) of biomedical alloys such as Co−Cr−Mo alloys holds immense potential for fabricating implants with complex geometry and tailored to meet patient-specific needs. However, layer-by-layer fabrication in AM processes results in undesired anisotropy due to the solidification texture and grain morphology. The present study aimed to investigate the effect of build orientation on the mechanical properties and functional performance, including tribocorrosion behavior and cytocompatibility of an orthopedic Co−28Cr−6Mo alloy manufactured by selective laser melting. Although the fabricated alloy showed weak crystallographic texture due to the rotational scanning strategy, significant anisotropy was found in the tensile properties due to the grain size and morphology. The presence of larger, elongated grains along the build direction as compared to smaller, equiaxed grains perpendicular to the build direction imparted the observed tensile anisotropy. Quantitative analysis based on current models for strengthening mechanisms is insufficient to explain the observed anisotropy, which is ascribed to the possible role of the cellular dendrites and stacking fault strengthening in Co−Cr alloys. Unlike the electrochemical behavior, which was largely independent of the build orientation, the bio-tribocorrosion studies revealed an anisotropic wear rate under fretting conditions. Osteoblast attachment and proliferation were found to be higher on the plane perpendicular to the build direction, owing to the differences in grain size. This work provides novel insights into the role of the manufacturing parameters in a selective-laser-melted Co−Cr alloy and its potential application in engineering load-bearing orthopedic implants.
“…Further, there were signs of three-body abrasion caused by the oxide and loose wear particles on the wear track, eventually forming micro-scratches on the matrix (Fig. 5 b,e) 9 , 12 , 47 . Figure 5 Surface profile map ( a ) and micrographs of worn surface morphologies ( b – f ), the cross-section of wear track ( d ) in BSE mode for EBM-processed high carbon martensitic stainless steel at 3 N and the optical microscopy of worn surface of the alumina ball at 3 N ( g ).…”
Section: Resultsmentioning
confidence: 99%
“…Several studies have shown that AM-processed SS parts can be superior to those conventionally manufactured counterparts. For example, AM- processed austenitic SS has been shown to have improved mechanical properties due to the finer microstructure (i.e., Hall–Petch relation) 3 , 8 , 9 . The heat treatment in AM-processed ferritic SS promoted the formation of additional precipitates, providing mechanical properties similar to conventional counterparts 3 , 10 .…”
The dry sliding wear behaviour of a high carbon martensitic stainless steel (HCMSS) consisting of ~ 22.5 vol% of chromium (Cr)- and vanadium (V)-rich carbides processed by electron beam melting (EBM) has been captured. The microstructure consisted of martensite and retained austenite phases with a homogeneous distribution of sub-micron-sized V-rich and micron-sized Cr-rich carbides, leading to relatively high hardness. The CoF decreased ~ 14.1% with increasing load in the steady-state, due to the material transferred from the wear track over the counterbody. The wear rate of the HCMSS compared to martensitic tool steel processed in the same manner, and it was nearly identical under low applied load. The dominant wear mechanism was removal of the steel matrix through abrasion, followed by the oxidation of the wear track, while three-body abrasive wear occurred with increasing load. A plastically deformed zone beneath the wear track was revealed through cross-sectional hardness mapping. Specific phenomena occurred with increasingly aggressive wear conditions were described with carbide cracking, pull-out of V-rich carbides and matrix cracking. This study revealed the wear performance of the additively manufactured HCMSS, which could pave the way for producing components for wear-related applications ranging from shafts to plastic injection moulds via EBM.
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