Explanation of the PLC Effect in Advanced High-Strength Medium-Mn Steels. A Review.

The paper reviews the recent works concerning the Portevin-Le Chatelier (PLC) effect in Advanced High-Strength Steels (AHSSs) with a special attention to high-strength medium-manganese steels. Theories explaining the mechanism of the plastic instability phenomenon in steels with medium- and high-Mn contents were discussed. The relationships between microstructural effects such as TRIP (Transformation-Induced Plasticity), TWIP (Twinning-Induced Plasticity) and the PLC effect were characterized. The effects of processing conditions including a deformation state (hot-rolled and cold-rolled) and strain parameters (deformation temperature, strain rate) were addressed. Factors affecting the value of critical strain for the activation of serrated flow behavior in particular in medium-manganese steels were described.

Analysis of Plastic Deformation Instabilities at Elevated Temperatures in Hot-Rolled Medium-Mn Steel.

The study addressed the microstructure and mechanical properties of hot-rolled advanced high-strength medium manganese steel. Some of the curves that were obtained in static tensile tests at deformation temperatures of 20-200°C showed the occurrence of the heterogeneous plastic deformation phenomenon, called the Portevin-Le Chatelier (PLC) effect. The deformation temperature significantly influenced a serration character. The correlations between the deformation temperature, serration range, microstructural features, and fracture behavior were investigated. The curves showed no Lüders elongation as a result of the thermomechanical processing applied. The serrated flow phenomenon was observed at 60 and 140 °C. The serration type was different and the most enhanced at 140 °C, where the PLC effect was present in both uniform and post-uniform elongation ranges. The disappearance of serrations at 200 °C was related to the increased diffusion intensity.

Peripheral eosinophilia and eosinophilic colitis during long-term azole therapy for pulmonary aspergillosis.

INTRODUCTION: Voriconazole and posaconazole are often used to treat invasive Aspergillus infections. We describe a patient with chronic pulmonary aspergillosis (CPA) who experienced peripheral eosinophilia and eosinophilic colitis while on voriconazole, and also experienced gastrointestinal symptoms and recurrent eosinophilia while on subsequent posaconazole therapy. CASE PRESENTATION: A 75-year-old female with recurrent pulmonary mucus plugs due to CPA was treated with long-term oral voriconazole. The patient had no clinical evidence of CPA exacerbations while on such antifungal treatment but developed peripheral eosinophilia, diarrhoea and eosinophilic colitis after >5 years of voriconazole therapy that resolved after cessation of azole therapy. Due to a CPA exacerbation after stopping voriconazole, the patient was started on posaconazole as an alternative CPA therapy. However, after 15 months, the patient developed a recurrence of peripheral eosinophilia and diarrhoea while on posaconazole. CONCLUSION: Long-term use of voriconazole and posaconazole can be used successfully to reduce the incidence of CPA exacerbations. However, such antifungal therapy may also lead to peripheral eosinophilia, diarrhoea and eosinophilic colitis.