An investigation of mechanical properties of Ti6Al4V produced by additive manufacturing (AM) in the as-printed condition have been conducted and compared with wrought alloys. The AM samples were built by Selective Laser Melting (SLM) and Electron Beam Melting (EBM) in 0°, 45° and 90°—relative to horizontal direction. Similarly, the wrought samples were also cut and tested in the same directions relative to the plate rolling direction. The microstructures of the samples were significantly different on all samples. α′ martensite was observed on the SLM, acicular α on EBM and combination of both on the wrought alloy. EBM samples had higher surface roughness (Ra) compared with both SLM and wrought alloy. SLM samples were comparatively harder than wrought alloy and EBM. Tensile strength of the wrought alloy was higher in all directions except for 45°, where SLM samples showed higher strength than both EBM and wrought alloy on that direction. The ductility of the wrought alloy was consistently higher than both SLM and EBM indicated by clear necking feature on the wrought alloy samples. Dimples were observed on all fracture surfaces.

Background: Osteotomes are bone cutting tools commonly reused in orthopedic surgical procedures. Despite undergoing rigorous cleaning, visual inspection, and sterilization procedures between every use, the condition of the cutting blade edge is commonly not qualitatively assessed. Subjective feedback from surgeons suggests a large variation in osteotome cutting-edge sharpness is found during use. This study seeks to investigate the retention of osteotome cutting-edge sharpness by comparing the wear resistance of as-supplied, electroless nickel, and titanium nitride coated osteotomes following a series of bone cutting tests. Methods: Changes in edge sharpness were assessed using visual inspection, depth penetration testing that quantified change in the blade sharpness index, and scanning electron microscopy visual analysis. Visual inspection of each osteotome blade edge was then compared to qualitative blade sharpness index measurement. Results: After use, no cutting-edge damage or change in blade sharpness was detected by visual examination of all three osteotomes; however, the as-supplied osteotome demonstrated 50% loss of blade sharpness index compared to 30% and 15% reduction for the electroless nickel and titanium nitride coated osteotomes, respectively. This finding was supported by scanning electron microscopy evaluation that found greater mechanical damage had occurred along the cutting edge of the as-supplied osteotome compared to the two coated with wear resistant materials. Conclusions: The rapid loss of blade sharpness found in the as-supplied osteotome supports the degradation in cutting performance frequently reported by surgeons. The findings from this study demonstrate blade sharpness index better detects cutting-edge wear compared to visual inspection. Results from this pilot study also suggest the coating of osteotomes in hard-wearing biocompatible materials assists in retaining cutting-edge sharpness over multiple uses. Further study using a larger sample size is required to validate these findings.

A selective laser melted Al-4.5Mg-0.6Sc-0.3Zr alloy, also known as Scalmalloy®, was cold-rolled at two different reductions in thickness to observe the effect on microstructure and mechanical properties. Optical microscopy, scanning electron microscopy, tensile testing with digital image correlation, surface roughness testing and microhardness testing was used to examine samples. Hardness increased significantly in the 30% cold-rolled condition – 20.2% in the horizontal plane, 12.5% in the transverse plane, and 18.2% in the longitudinal plane. Surface roughness was reduced to as low as 1.2μm for cold-rolled conditions compared to >15μm for as-built conditions. Yield strengths were less for cold-rolled conditions compared to as-built and ultimate tensile strengths were similar for as-built and 10% cold rolled conditions. However, 30% cold-rolled condition saw a 10.8% increase compared to as built. Strain distribution among samples was uniform for as-built conditions but concentrated in certain areas for cold-rolled conditions. SEM micrographs of fracture surfaces showed some very ductile fractures evident from dimpling. The microstructure was heavily deformed for all cold-rolled conditions in all build directions showing flattened, elongated grains and grain refinement in both the coarse grain and fine grain regions present in Scalmalloy, especially for the 30% cold-rolled condition.

The scandium-zirconium modified aluminum alloy Scalmalloy is additively manufactured using Selective Laser Melting in the Renishaw AM 400 SLM machine. THE optimal SLM process parameter window concerning relative densities exceeding 99% was investigated. Scalmalloy powder was characterized concerning particle morphology, qualitative particle size distribution, and inner gas pores. Full available SLM laser power of Renishaw AM 400 SLM machine was applied to increase productivity as much as possible. Archimedes density method and metallographic cross-sections were used to determine relative densities, whereby all samples printed exceeded 99%. THE optimal SLM process parameter window for the laser power of 400W was found to be in the range of 40-110J/mm3 where scan speed is doubled compared to other literature using 200W, thus productivity is greatly increased. Microhardness testing was also performed on all samples and showed the successful suppression of Al3(Sc1-xZrx) precipitates, whereby subsequent age hardening may be performed post-process.

BackgroundOsteotomes are bone cutting tools commonly reused in orthopedic surgical procedures. Despite undergoing rigorous cleaning, visual inspection and sterilization procedures between every use, the condition of the cutting blade edge is commonly not qualitatively assessed. Subjective feedback from surgeons suggests a large variation in osteotome cutting edge sharpness is found during use. This study seeks to investigate the retention of osteotome cutting-edge sharpness by comparing the wear resistance of as-supplied, electroless nickel, and titanium nitride coated osteotomes following a series of bone cutting tests.MethodsChanges in edge sharpness were assessed using visual inspection, depth penetration testing that quantified change in the blade sharpness index and scanning electron microscopy visual analysis. Visual inspection of each osteotome blade edge was then compared to qualitative blade sharpness index measurement.ResultsAfter use, no cutting-edge damage or change in blade sharpness was detected by visual examination of all three osteotomes however the as-supplied osteotome demonstrated 50% loss of blade sharpness index compared to 30% and 15% reduction for the electroless nickel and titanium nitride coated osteotomes respectively. This finding was supported by scanning electron microscopy evaluation that found greater mechanical damage had occurred along the cutting-edge of the as-supplied osteotome compared to the two coated with wear resistant materials.ConclusionsThe rapid loss of blade sharpness found in the as-supplied osteotome supports the degradation in cutting performance frequently reported by surgeons. The findings from this study demonstrates blade sharpness index better detects cutting edge wear compared to visual inspection. Results from this pilot study also suggest the coating of osteotomes in hard-wearing biocompatible materials assists in retaining cutting edge sharpness over multiple uses. Further study using a larger sample size is required to validate these findings.