The presence of chloride ions in the stainless steel usage environment

Chlorine ions are widely present, such as salt/sweat/seawater/sea breeze/soil, and so on. Stainless steel corrodes rapidly in the presence of chloride ions, even surpassing ordinary low-carbon steel. So there are requirements for the use environment of stainless steel, and it is necessary to regularly wipe, remove dust, and maintain cleanliness and dryness. There is an example in the United States where a company uses an oak container to hold a solution containing chloride ions, which has been in use for nearly a hundred years. In the 1990s, it was planned to be replaced, but due to the lack of modern oak materials, the container leaked due to corrosion 16 days after being replaced with stainless steel.
Without solid solution treatment
The alloy elements did not dissolve into the matrix, resulting in low alloy content and poor corrosion resistance in the matrix structure.
Natural intergranular corrosion
This material without titanium and niobium tends to exhibit intergranular corrosion. Adding titanium and niobium, combined with stabilization treatment, can reduce intergranular corrosion. A type of high alloy steel that can resist corrosion in air or chemical corrosive media. Stainless steel has a beautiful surface and good corrosion resistance, without the need for surface treatment such as plating, and utilizes the inherent surface properties of stainless steel. It is commonly used in various types of steel and is called stainless steel. High alloy steels such as 13 chromium steel and 18-8 chromium nickel steel represent performance. From the perspective of Metallography, because the stainless steel contains chromium, a very thin chromium film is formed on the surface. This film is separated from the oxygen invading in the steel and plays a corrosion resistant role. In order to maintain the inherent corrosion resistance of stainless steel, steel must contain more than 12% chromium. For applications requiring welding, the lower carbon content minimizes the precipitation of carbides in the heat affected zone near the weld seam, which may lead to intergranular corrosion of stainless steel in certain environments.
dust
Production is often carried out in dusty areas, where there is often a lot of dust in the air that constantly falls on the surface of the equipment. They can be removed with water or alkaline solution. However, adhering dirt requires high-pressure water or steam for cleaning.
Float iron powder or embedded iron
On any surface, free iron will rust and cause corrosion of stainless steel. Therefore, it must be cleared. Floating powder can generally be removed together with dust. Some have strong adhesion and must be treated with embedded iron. In addition to dust, there are many sources of surface iron, including cleaning with ordinary carbon steel wire brushes, shot peening with sand, glass beads, or other abrasives previously used on plain carbon steel, low alloy steel, or cast iron parts, or grinding non stainless steel products mentioned earlier near stainless steel components and equipment. If protective measures are not taken for stainless steel during the cutting or lifting process, steel wire ropes, lifting tools, and the iron on the workbench can easily embed or stain the surface. The ordering requirements and post production inspection can prevent and detect the presence of free iron. ASTM standard A380 [3] specifies the rust test method for inspecting iron or steel particles on the surface of stainless steel. When it is required that there must be no iron present, this inspection method should be used. If the results are satisfactory, wash the surface with clean pure water or nitric acid until the dark blue color completely disappears.