RESUMO O aço AISI 316L é muito aplicado como biomaterial de baixo custo em próteses e equipamentos cirúrgicos, dentre outras aplicações. Estas aplicações se devem à sua boa resistência à corrosão em presença de meios contendo fluidos corporais. Muito embora o aço apresente as características mencionadas, estas poderão ser comprometidas com a formação de martensita alfa linha (fase magnética) induzida por deformação a frio. Neste caso, o presente trabalho, teve como objetivo investigar os efeitos de laminação a frio no surgimento de fase martensítica. Para tanto foram realizadas três diferentes deformações. A chapa como recebida e as amostras deformadas foram submetidas a ensaios de ferritoscopia, microdureza Vickers e análise microestrutural por microscopia eletrônica de varredura, MEV. Foi observado que nas amostras deformadas a frio houve o surgimento de fase magnética (provavelmente martensita alfa linha) e aumento da microdureza, devido ao encruamento e à presença de fases induzidas por deformação.

ABSTRACT AISI 316L steel is widely used as a low cost biomaterial in prostheses and surgical equipment, among other applications. These applications are due to their good corrosion resistance in the presence of environment containing body fluids. Although this steel has the mentioned characteristics, it may be compromised with the formation of alpha prime martensite (magnetic phase) induced by plastic deformation. In this case, the present work aimed to investigate the cold rolling effects on the martensitic phase formation. For that, three different deformations were performed. The plate as received and the deformed samples were subjected to ferritoscopy, Vickers microhardness and microstructural analysis by scanning electron microscopy, SEM. It was observed that in cold deformed samples there was the magnetic phase appearance (probably alpha prime martensite) and microhardness increase, due to the hardening and the deformation induced phases presence.

ABSTRACT This work examined the pitting corrosion resistance of two types of duplex stainless steels: UNS S31803, with molybdenum, and UNS S32304, without molybdenum. Cyclic potentiodynamic polarization and critical pitting temperature (CPT) tests were performed in 3.5 wt% NaCl solution. Scanning electron microscopy (SEM) was used for analysis of the pits on the surface of samples. The two steels studied presented susceptible to pitting corrosion in 3.5 wt% NaCl solution. UNS S31803 steel showed a higher corrosion potential (Ecorr), pitting potential (Epit), and polarization resistance (Rp) compared to UNS S32304 steel. It was also observed that the UNS S31803 steel showed higher capacity to repassivation and CPT than the UNS S32304 steel.

Abstract This work aims to evaluate the performance of anticorrosive thermoplastic coatings in cold rolled steel sheets. Two types of thermoplastic coatings were studied: polystyrene (PS) and cornstarch. These types of coatings are applied for protection against corrosion during transport and storage of steel plates after cold rolling until delivery to stamping or other processing. The good performance for these coatings is suitably standardized to ABNT NBR 5915-2: 2013 and ASTM A1008 / A1008M-2016. According to corrosion tests carried out in saline chamber, the coatings were satisfactory in different degrees of guarantee of corrosion protection on ASTM 1080 steel, in accordance with standards mentioned.

This paper explored the effect of adding organic fibers from either bamboo or sugarcane on the mechanical properties of concrete. Cylindrical and prismatic specimens were made containing 2% and 5% v/w (volume to weight) of vegetable fibers to concrete. Following 28 days of curing period, the samples were evaluated for compressive strength, tensile strength using diametric compression, tensile strength during bending and static modulus. It was discovered that all concretes produced met the minimum strength of 20 MPa recommended by NBR 6118 for structural purposes, and it was observed an increase of the compressive strength on the specimens with addition of organic fibers. Moreover, an increase in the compressive strength was observed in the specimens with fiber addition, although no significant variation of water absorption was noticed when compared with the standard concrete. In conclusion, the concrete containing 2% v/w of bamboo fibers showed better mechanical strength and static modulus of elasticity when compared to both concrete with sugar cane fibers addition and the concrete without any additional fibers.

Alternatives to the plasma spraying method have been developed to obtain calcium phosphate coatings, like the biomimetic method. This process is a physicochemical method in which a substrate is soaked in a solution that simulates the physiological conditions, for a period of time enough to form a desirable layer of the calcium phosphate on the substrate. The titanium substrate usually investigated in the literature is subjected to an alkali treatment to induce the calcium phosphate formation and improve adhesion of the coating. The goals of this work are to compare the effect of alkaline treatments on two substrates titanium alloy and stainless steel, usually used for implants and orthopedic prostheses. The metallic substrates were treated with NaOH 5N at 60 °C for 24 h and NaOH 20N at 90 °C for 30 min. The samples were immersed in simulated body fluid for 3 days and in a solution with a higher calcium concentration for another three days. The modified substrates and coatings were characterized using profilometry, scanning electron microscopy and X-ray diffraction analysis. The alkaline treatment modified the characteristics of both substrates and allowed the nucleation a calcium phosphate film.