Hi,
considering metallic components in environments like air or steam you will nearly always have corrosion taking place. In my opinion, it is always a question of how significant the process is!
For example, assuming a bar of stainless steel at room temperature in air. The diameter of the bar is designed to withstand a certain stress. Generally, corrosion, in this case oxidation of the material, will form oxide on the bars surface and the diameter of the bar will shrink (oxidation consumes metal). However, at room temperature stainless steel will form Chromium-rich oxide and the growth rate of this oxide at room temperature is very very very slow. Hence in this case corrosion will not play an important role regarding the mechanical properties of the component.
However, the same bar at elevated temperatures will behave different, as at higher temperatures Iron-rich oxides can form which grow much faster than chromium-rich oxides and in addition the higher temperature accelerates oxidation. This means, the bars diameter can shrink much faster than in the first case and the maximum stress which the bar can withstand will decrease. The mechanical properties change due to corrosion.
I hope this example gives an idea of the question if corrosion is significant to mechanical properties or not and suits your question.
Best regards
Hi, sir. Corrosion rate are affected by humidity, temperature, rain, wind, impurities and metal wet times and are expressed in terms of mm per year of surface wastage. Usually, a corrosion allowance is provided in the design thickness of equipment such as vessels and pipework. As far as I know, corrosion allowances are normally established by the end user and are somewhat based on personal preferences and industry tradition.
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