Pulse and pulse reverse plating—Conceptual,advantages and applications

Shape memory alloys (SMAs) are a class of alloys that possess numerous unique characteristics. They offer complete shape recovery after experiencing large strains, energy dissipation through hysteresis of response, excellent resistance to corrosion, high fatigue resistance, and high strength. These features of SMAs, which can be exploited for the use in control of civil structures subjected to seismic events, have attracted the interest of many researchers in structural engineering over the past decades. This article presents an extensive review of seismic applications of SMAs. First, a basic description of two unique effects of SMAs, namely shape memory and superelastic effect, is provided. Then, the mechanical characteristics of the most commonly used SMAs are discussed. Next, the material models proposed to capture the response of SMAs in seismic applications are briefly introduced. Finally, applications of SMAs to buildings and bridges to improve seismic response are thoroughly reviewed.

Seismic Response Control Using Shape Memory Alloys: A Review

Effects of scan rate on the potentiodynamic polarization curve obtained to determine the Tafel slopes and corrosion current density

http://www3.unisi.it/ricerca/centri/crisma/FEPA/publications/virtanen.pdf

Special modes of corrosion under physiological and simulated physiological conditions.

Inconel 718 is a high nickel content superalloy possessing high strength at elevated temperatures and resistance to oxidation and corrosion. The non-traditional manufacturing process of wire-electrical discharge machining (EDM) possesses many advantages over traditional machining during the manufacture of Inconel 718 parts. However, certain detrimental effects are also present and are due in large part to the formation of the recast layer. An experimental investigation was conducted to determine the main EDM parameters which contribute to recast layer formation in Inconel 718. It was found that average recast layer thickness increased primarily with energy per spark, peak discharge current, and current pulse duration. Over the range of parameters tested, the recast layer was observed to be between 5 and 9 μm in average thickness, although highly variable in nature. The recast material was found to possess in-plane tensile residual stresses, as well as lower hardness and elastic modulus than the bulk material.

Investigation of the effect of process parameters on the formation and characteristics of recast layer in wire-EDM of Inconel 718

Electrochemical corrosion studies on Co–Cr–Mo implant alloy in biological solutions

The electrochemical corrosion behavior of Ti–6Al–4V implant alloy was investigated in three biological solutions, i.e. urine, serum and joint fluid. The corrosion properties of Ti–6Al–4V implant alloys were examined by using electrochemical techniques, such as the potentiodynamic method, cyclic voltammetry, electrochemical impedance spectroscopy (EIS). The electrochemical corrosion characteristics of Ti–6Al–4V implant alloys in three biological solutions were measured in terms of the corrosion potential (Ecorr), the corrosion current density (icorr), and ac polarization resistance (Rp). The corrosion kinetic parameters were calculated from both the Tafel plot analyses and EIS analyses. The dependence of impedance versus potentials was studied at 37 °C at various offset potentials in three biological solutions. The ac circuit model for Ti–6Al–4V implant alloy at corrosion interface in biological solution was proposed, which was based on a simple Randles equivalent circuit. It was found that the Ti–6Al–4V implant alloy in three biological solutions showed a characteristic of a capacitive behavior. The experimental results of Tafel plot analyses were found in good agreement with that of EIS analyses.

Electrochemical corrosion properties of Ti–6Al–4V implant alloy in the biological environment

In this research, quenched and tempered martensitic stainless steels, AISI 440A, were subjected to multi-cutting passes by wire electrical discharge machining (WEDM). The WEDM is widely applied to final surface shaping of harden steel. The steel was roughly machined at first cutting pass, semi-finished by two cutting passes, and then finished by one cutting passes, all machined by WEDM. The negatively polarized wire electrode (NPWE) was used for all of these four cutting passes. Some finished specimens were further extra-finished by using the positively polarized wire electrode (PPWE). Microstructures of the finished surfaces using NPWE as well as PPWE were studied with scanning and transmission electron microscopes (SEM and TEM). Chemical composition was analyzed by an energy-dispersive X-ray spectrometer (EDX) integrated in SEM or TEM. The study of the finished surfaces with NPWE shows that a heat-affected zone (HAZ) of about 1.5 μm thick was developed. The HAZ is composed of very fine equiaxed martensitic grains of about 200 nm with concentrated dislocations, but the temper-induced carbides were not found. A few spherical deposits of wire electrode material were also registered. Oxides with ca. 10 nm in diameter were detected around the deposits. The spherical deposits were characterized as “bull eye” in TEM according to their appearance. For the surface finished with PPWE, no obvious HAZ was detected, but a very thin (

Microstructure analysis of the martensitic stainless steel surface fine-cut by the wire electrode discharge machining (WEDM)

In this paper the heat-affected zones (HAZs) of the Inconel 718 sheets welded with electron-beam welding (EBW) were studied by using hardness measurement, metallographic etch and electrochemically potentiostatic etch methods. Before EBW, the Inconel 718 sheets were pretreated in three different conditions: as-received, solution- and precipitation-treatments. The results show that there is an obvious difference in the dimension of the widths of HAZs evaluated by the methods. The width, ca. 1.5 mm, of the HAZ in solution-pretreated weld can be estimated based on the variation of its hardness distribution curve. But the HAZs in as-received and precipitation-pretreated welds were difficult to detect from their hardness distribution curves. After metallographic etching, the HAZs in the welds were very hard to observe with optical microscope, but those with a width within 100 μm in solution- and precipitation-pretreated welds, except in as-received weld, can be observed with scanning electron microscope (SEM). The HAZ with a width ca. 300 μm of each weld can be revealed by using anodically potentiostatic etching in 3.5 wt.% NaCl solution due to different corrosion rates among the HAZ, fusion zone and base metal in the weld. The above-mentioned behavior of HAZs evaluated by different methods was discussed in detail in this work.

C.A. Huang

Papers

Electrochemical corrosion studies on Co–Cr–Mo implant alloy in biological solutions

Electrochemical corrosion properties of Ti–6Al–4V implant alloy in the biological environment

Microstructure analysis of the martensitic stainless steel surface fine-cut by the wire electrode discharge machining (WEDM)

A study of the heat-affected zone (HAZ) of an Inconel 718 sheet welded with electron-beam welding (EBW)

Investigation on the corrosion behavior of Ti–6Al–4V implant alloy by electrochemical techniques