Geophysics
Mahammad Laribaghal; Mehdi Khorasanian; Mostafa Eskandari; Seyed Reza Alavi Zaree
Abstract
In steel production plants, such as those manufacturing sheets, pipes, and round bars, raw materials are annealed in preheating furnaces at approximately 1200 oC before undergoing hot deformation process. Substantial oxidation and loss of raw steel materials occur in preheating furnaces, resulting in ...
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In steel production plants, such as those manufacturing sheets, pipes, and round bars, raw materials are annealed in preheating furnaces at approximately 1200 oC before undergoing hot deformation process. Substantial oxidation and loss of raw steel materials occur in preheating furnaces, resulting in significant economic losses. A potential solution to reduce losses in this scenario is the application of protective ceramic coatings. This research investigates the effect of a ceramic coating based on Al2O3-SiO2 on the oxidation behavior of steel sheets. The industrial-scale effect of the coating on the oxidation of steel slabs is also examined. The coating was applied using a spray method with slurry ceramic materials dispersed through a compressed air flow. Thickness measurement tests, scanning electron microscopy, and EDS analysis were conducted to evaluate the kinetics, microstructure and the oxidation behavior of the coatings. The findings indicate that the oxidation kinetics for uncoated steel sheets follow a parabolic trend, while the kinetics for ceramic coated samples exhibit a slower logarithmic behavior. The application of the coating resulted in a reduction of the oxide layer thickness by less than 30% compared to the uncoated samples, attributed to a lower diffusion coefficient in the coated samples. In industrial Test, the application of the ceramic coating on St52 slabs led to a significant reduction in the oxide layer thickness and easier peel of the oxide layers. These show that the use of such ceramic coating for materials in preheating furnaces can effectively reduce oxidation losses and enhance mechanical quality of final products.
Geophysics
Mahammad Laribaghal; mehdi Torfi; Mehdi Khorasanian; Seyed Reza Alavi Zaree
Abstract
Fin-pass rolls are the latest series of rolls in electric resistance welding (ERW) pipe production lines that form the sheets to tubular shape and adjust the edges of the sheet for welding. The rolls (made of AISI 8622 steel) lose their proper function after about 10 years of operation due to severe ...
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Fin-pass rolls are the latest series of rolls in electric resistance welding (ERW) pipe production lines that form the sheets to tubular shape and adjust the edges of the sheet for welding. The rolls (made of AISI 8622 steel) lose their proper function after about 10 years of operation due to severe wear and change of their original surface profile. The worn portions were removed by grinding and replaced by an AISI D2 high carbon steel ring to repair these rolls. After a short time of service (about one year), the edge of the repair ring was exposed to severe spalling and fracture. The present study investigated the causes of the rapid failure of the AISI D2 repair ring and proposed a solution to the problem. The surface morphology, hardness, and wear resistance were studied. Moreover, the stress analysis of fin-pass rolls was studied using ABAQUS 6.14 finite element software for the closer investigation of the failure mechanism. The leading cause of spalling was the inherent brittleness of the AISI D2 steel and the presence of a high-stress concentration at the edges of the repair ring. To overcome this problem, carburized AISI P20 steel, case hardened AISI 4140 steel, and hard chromium electroplated AISI 4140 steel were replaced, and the resulting properties were studied. The highest resistance to spalling and wear occurred with carburized AISI P20 steel because of the high surface hardness and the gradual increase of toughness from the surface to the depth in the carburizing process, increasing the wear resistance and retarding the growth of fatigue cracks.