Author : Basukumar H K 1
Date of Publication :25th May 2017
Abstract: Investigations were carried out to study the corrosion behaviour, stress corrosion cracking (SCC) and hydrogen embrittlement (HE) of low carbon steels in acidic media by weight loss measurement and Impact test to fracture respectively. The effect on corrosion behavior of metal with different concentration of acidic media was monitored for a specified immersion period. The mechanism of stress-corrosion cracking and hydrogen embrittlement in low carbon steels was investigated using notched specimens, under high velocity loading conditions leading sudden fracture. It was observed that nitric acid environment was most corrosive to steels because of its oxidizing nature on the other hand the ammonium thiocynate environment showed hydrogen embrittlement of the material. From the experimental results, it can be observed that material experiences the ductile-to-brittle transition with increasing in soaking period. On analysis, at room temperature, HNO3 was found to be more aggressive towards mild steel compare to ammonium thiocynate. Few studies have been carried out to determine the influence of hydrogen on structural steel and its mechanical characteristics, in turn mechanism of hydrogen embrittlement. The result of impact test shows a decreasing trend indicating of reduction of material toughness. The material exhibit brittle failure in NH4SCN treated specimen than the HNO3 treated specimen. The surface analysis also carried out with the help of Scanning electron microscope (SEM). Overall the result suggests that corrosion was observed significantly HNO3 medium. These deductions are due to higher carbon content in medium carbon steel coupled with various aggressive corrosion constituents contained in these media. Hydrogen embrittlement, as well as carbon cracking, is responsible for SCC of these materials in the acidic media.
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