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Go to Editorial ManagerThe present study aims to investigate the influence of heat treatment and surface finish on the behavior of crevice corrosion resistance of AISI 410 and 416 martensitic stainless steels thus, to quantify the conditions at which crevice corrosion minimize as possible. The experimental work carried out during this study involves material selection, chemical composition tests, specimens preparation before heat treatments, austenitizing at temperature range (925-1010˚C) and for holding time periods of (30, 45 and 90 min), air and oil quenching followed by tempering at heating range of (205- 605 ̊C) and for 45 min, micro hardness tests, specimens grinding, surface roughness measurements, crevice corrosion tests, crevice evaluation and microstructure tests. Theoretically, empirical equations for crevice maximum depth under the effect of surface roughness and hardness for both AISI 410 and 416 steels were determined. While for microstructure analysis, carbides average area was determined by using the ImageJ analysis program and a mathematical model was also predicted. Results showed that, as hardness and surface roughness increase crevice corrosion resistance decreases. Therefore, material treated by annealing can minimize crevice corrosion rates more than that treated with hardening.
Brazing is one of the best methods of graphite to graphite or to metals joining. But the major problem associating the graphite brazing is the poor wetting by the conventional molten fillers. For this reason, scientists have produced a special filler metal based on active elements which interacts with graphite to form carbides. Also, recently another technique to overcome the wetting problem was introduced by H. Ohmura and T. Yoshida. It included inserting an intermediate layer of pure iron foil inside the copper filler. In the present work, another filler combination of Cu/ steel/Cu foils is proposed as new filler technique for graphite brazing. It was found that, it produced a succeeded joint with a good properties consisted of a columnar phase which resulted from the partially dissolution of iron in molten copper. Additionally, the increasing of brazing time caused reducing the thickness of the steel central layer and increasing the thickness of the columnar phase layers. The x-ray diffraction test developed that, the joints contained two carbide types, iron and copper free elements.