Effect of silver in thermal treatments of Fe-Mn-C degradable metals: Implications for stent processing.

Twinning-induced plasticity (TWIP) steels are considered excellent materials for manufacturing products requiring extremely high mechanical properties for various applications including thin medical devices, such as biodegradable intravascular stents. It is also proven that the addition of Ag can guarantee an appropriate degradation while implanted in human body without affecting its bioactive properties. In order to develop an optimized manufacturing process for thin stents, the effect of Ag on the recrystallization behavior of TWIP steels needs to be elucidated.

On the Recycling of Water Atomized Powder and the Effects on Properties of L-PBF Processed 4130 Low-Alloy Steel.

The microstructure and mechanical properties of a 4130-grade steel processed by L-PBF using a feedstock of low-cost water atomized powder have been investigated considering the effects of powder recycling. Chemical analysis of the recycled powder showed a constant amount of alloying elements with a slight reduction in oxygen content. The as-built microstructure was mainly composed of a martensitic structure separated by a high fraction of low-angle grain boundaries, suggesting the application of a direct tempering treatment starting from the as-built condition as a cost-effective post-process thermal treatment rather than the conventional quench and tempering treatment.

Six-Month Long Degradation Tests of Biodegradable Twinning-Induced Plasticity Steels Alloyed with Ag for Stent Applications.

Twinning-induced plasticity (TWIP) Fe-Mn-C steels are biodegradable metals with far superior mechanical properties to any biodegradable metal, including Mg alloys, used in commercially available devices. For this reason, the use of Fe-Mn-C alloys to produce thinner and thinner implants can be exploited for overcoming the device size limitations that biodegradable stents still present. However, Fe-Mn steels are known to form a phosphate layer on their surface over long implantation times in animals, preventing device degradation in the required timeframe.

Hydrogen Embrittlement Behavior of 18Ni 300 Maraging Steel Produced by Selective Laser Melting.

A study was performed to investigate the hydrogen embrittlement behavior of 18-Ni 300 maraging steel produced by selective laser melting and subjected to different heat treatment strategies. Hydrogen was pre-charged into the tensile samples by an electro-chemical method at the constant current density of 1 A m and 50 A m for 48 h at room temperature. Charged and uncharged specimens were subjected to tensile tests and the hydrogen concentration was eventually analysed using quadrupole mass spectroscopy.

Cerebral venous thrombosis: a rare complication of herpes simplex encephalitis.

We report a case of classic HSE with early neurological relapse 7 days after onset of acyclovir treatment secondary to cerebral venous thrombosis (CVT). The development of CVT after meningoencephalitis has been described with neurotropic viruses such as HSV, HIV, or enteroviruses and also bacterial or fungal agents. CVT is probably the consequence of the inflammation secondary to these infections.