Masashi Nishimoto

The role of Mo alloying in the pit initiation process at MnS inclusions in stainless steels was investigated by measuring polarization curves, depassivation pH, and scanning electron microscopy. Molybdenum existed in the steel matrix but was not detected in the MnS inclusions in Type 316 stainless steel. While Mo alloying did not inhibit the dissolution of the MnS inclusions in a NaCl solution, neither a metastable nor a stable pit occurred in the small areas with the MnS inclusions in the Mo-ad

A sensing plate for the simultaneous measurements of pH and Cl− concentration was fabricated. Terbium–dipicolinic acid complex (Tb–DPA) and quinine sulphate were used to measure the pH and Cl− concentration, respectively. In the incubation period of the crevice corrosion, the pH inside the crevice gradually decreased from 3.0 to ca. 2.0, and the Cl− concentration increases from 0.01 to ca. 0.18 M. The generation of the micro-pit led to a sharp decrease in pH to below 0.5 and an increase in the C

The quantitative effects of the Cr concentration in (Mn,Cr)S inclusions in stainless steel on the dissolution and surface oxide properties of inclusions were investigated by microscale polarization and Auger electron spectroscopy. The onset potential of inclusion dissolution increased with the Cr concentration and reached the transpassive region of stainless steel when the Cr/(Mn + Cr) ratio of the inclusions was greater than 0.5. The surface oxide layer on Cr-rich inclusions was thicker and mor

Spark plasma sintering was used to fabricate type 304L stainless steel specimens containing artificial manganese sulfide (MnS) inclusions, and a microelectrochemical technique was used to characterize the pit initiation behavior at the MnS. A 200 μm square electrode area that included an artificial MnS particle was potentiodynamically polarized in 0.1 M NaCl, and the electrode surface was observed in situ by optical microscopy. The anodic dissolution of the MnS particle was observed in the passi

This paper reviews recent studies on the relationships between local electrochemical properties at the steel/inclusion boundary and pitting corrosion resistance of stainless steels. The effect of Mo addition to the steel matrix on the local dissolution behavior at the steel/inclusion boundary is explained. The inhibition of inclusion dissolution is beneficial for improving the pitting corrosion resistance of stainless steels. The importance of spark plasma sintering and microelectrochemical tech

Micro-scale polarization data from small surface areas of stainless steels with either CeS or MnS inclusions was measured in NaCl and Na2SO4 solutions to elucidate the dissolution and pit initiation behavior of both types of inclusions. Stable pitting was initiated at the CeS inclusion at potentials which exceeded the dissolution potential region of the CeS inclusion, whereas a stable pit at the MnS inclusion was initiated in the dissolution potential range of the MnS inclusion. Thermodynamic ca

Abstract Carbon steels are widely used as infrastructure components owing to their high strength, ductility, and weldability. However, as corrosion degrades critical infrastructure components, exploring the relationship between the microstructure and corrosion resistance of carbon steel is of particular interest in engineering. To analyze this relationship, it is first essential to evaluate the corrosion resistance of each microstructure in a carbon steel specimen with a single chemical composit

We report herein the case of a 78-year-old man found to have abdominal aortic aneurysm (AAA) with an isolated left-sided inferior vena cava (IVC). The patient was admitted to our hospital to undergo surgery for the AAA. The computed tomography revealed the sacular aneurysm of the infrarenal abdominal aorta (60 x 40 mm) and right common iliac aneurysm (30 x 30 mm). At the same time the left sided IVC was found by the CT. This IVC (13 mm wide) ascended 76 mm, dorsally to the ureter, the left side

Controlling the electrochemical properties of non-metallic inclusions is of substantial interest in the design of corrosion-resistant alloys. To the best of our knowledge, the dissolution and pitting corrosion behavior of selenide inclusions in stainless steels and the improvement of the pitting corrosion resistance of type 304 stainless steels via Se microalloying have not been investigated. In this study, stainless steel specimens containing artificial MnS and MnSe inclusions were fabricated v

The pitting corrosion behavior of SBHS500 steel in boric-borate buffer solutions containing chloride ions was investigated by macroscale and microscale polarization, immersion tests, optical microscopy, and scanning electron microscopy. Calcium sulfide inclusions (CaS) existed in the SBHS500 steel. When the specimen was immersed in a boric-borate buffer solution (pH 8.0) containing 10 mM NaCl for 24 h at 25°C, the steel matrix was not corroded. However, partial dissolution of the CaS inclusions

The initiation site of pitting corrosion of 17–4PH stainless steel in 1 M NaCl was identified by SEM/EDS analysis after micro-scale galvanostatic polarization. A commercially available 17–4PH stainless steel was solution treated at 1040°C for 1 h and subsequently tempered, and as-quenched, 482°C-tempered, and 621°C-tempered specimens were made. All specimens contained MnS and NbC particles with a size of approximately 500 nm. In addition, the precipitation of ε-Cu was observed in the tempered sp

We described the severity of skin lesions and detected peripheral eosinophil counts (Eos) and serum eosinophil cationic protein levels (s-ECP) in 81 patients with atopic dermatitis (male 33, female 48, age 20.7 +/- 8.8) at the first consultation. Eos were 583.3 +/- 560.2/mm3 and s-ECP were 18.0 +/- 21.7 micrograms/l (normal 6.88 +/- 3.46). After approximately 30 days treatment, the improvement of dermatitis were estimated and those lavatory findings were rechecked. Eos were 446.7 +/- 367.6/mm3 a

The effects of the annealing temperature on the electrochemical properties, anodic dissolution, and pitting corrosion resistance of MnS inclusions in 18mass％Cr ferritic stainless steel are investigated by scanning electron microscopy, macroscale polarization, and microscale polarization. The MnS inclusions in the specimens annealed at higher temperatures have higher Cr concentrations and lower Mn concentrations. The onset potential of the inclusion dissolution and the pitting corrosion resistanc

The dissolution of Fe-15Cr alloy during potentiodynamic polarization in sulfuric acid was quantified in situ using inductively coupled plasma mass spectrometry. The potential dependence of the very low dissolution rates of Fe and Cr in the passive state was characterized. The selective dissolution of Fe was observed in the lower passive potential range, while Cr dissolved preferentially in the higher passive potential range. The discrepancy between the polarization curve and current from the Fe