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Additive Manufacturing (AM) is a technique where freeform structures are produced by building up material layer by layer. Mostly, AM technologies use powder material as feedstock and different heat sources, which can lead to different problems during the process. WAAM (Wire and Arc Additive Manufacturing) is a technology which has been investigated in the last 30 years, although the first patent was introduced almost 100 years ago. It is a combination of welding and additive manufacturing technologies and one of the potential future application of this technology could be producing the duplex stainless steels. Their excellent corrosion resistance and high mechanical strength make them a favourable choice for oil and gas industrial sectors or off-shore applications. However, they are more difficult to machine than other stainless steels due to their high strength and high work hardening rate, but WAAM could solve some of the problems which occur in their production. Possibility of producing duplex stainless steel product using WAAM is investigated in this paper. Different sets of welding parameters were tested until the most optimal one was chosen, and WAAM product (wall) was made with MIG welding method, using the robotic station.

Shielding gases, i.e., argon or an argon-nitrogen mixture, are normally used during the laser-beam welding of duplex stainless steel. Helium is also often added to the argon. The effect of the type of shielding gasargon, nitrogen, helium and their mixtureson the geometrical characteristics of laser-welded joints of the duplex steel W.Nr. 1.4462 was studied. The welding was carried out according to the experimental model with mixtures. The effect of the welding speed and the gas flow rate were additionally explored using a factorial experiment. Obtained data were statistically processed and mathematical modeling, applying the method of response surfaces, was carried out. The analysis revealed that the impact of the shielding gas mixtures on the geometrical characteristics of the joint is significant, while it is not so significant for the microstructure. The effect of the gas flow rate on the geometrical characteristics was registered, while the effect of the heat input is the most significant. Special cubic, quadratic and reduced quadratic models, depicting effects of the shielding gas on geometrical characteristics and microstructure of welded joint, were obtained.

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Bone tissue banks are necessary for collection, production, testing, packaging, storage and delivery of bone transplants. Bone tissue bank is a link between the donor and the recipient by which the donation becomes a medium of health improvement for both the donor and the recipient. At the Department of Orthopedics, Mostar University Clinical Hospital, about 200 total hip replacements are performed per year. Most patients undergoing total hip replacement surgery (90%) have been diagnosed with osteoarthritis, and they are suitable donors, having in mind their age and comorbidities. In the same Department, around 50 procedures that require bone transplants are performed per year. A team of highly competent surgeons are working on an intensive process of adaptation oriented to quality improvement and intensification of the activity, both with the goal of meeting the standards of excellence in orthopedic surgery. The presence of a bone tissue bank has a favorable impact on the quality of health care owing to bone transplant availability, as well as on the scientific role of a highly specialized institution that examines the properties of bone tissue.