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What causes stainless steel to rust and how it prevent it?

Can stainless steel rust?

Can Stainless steel  is highly recognized because of its high capacity to resist rust and other related corrosion hence the popularity in the market especially in kitchen ware, laundry and manufacturing industries. However, one of the biggest myths that people have about the material is that stainless steel is not rust prone at all. Surprisingly, it is more resistant to corrosion than the regular steel but it can corrode in specific conditions. To maintain the stainless steel as long lasting and good looking as possible it is necessary to know why it can rust and how this can be prevented.

Can stainless steel rust?

Can stainless steel rust?Understanding Stainless Steel and Rust

stainless steel rust is greatly appreciated for its anticorrosive property, it has a wide use in household appliances for example refrigateators, industrial uses such as machinery and hardware and construction uses such as door handles, pillars etc. Nonetheless, while stainless steel seems to provide better protection as compared to regular steel it is not entirely resistant to rust. It is very durable because of a layer of chromium oxide that forms because of the content of at least 10.5% of chromium in the alloy. This thin passive layer shields the steel underneath from two key agents of rusting, which are oxygen and moisture. Nevertheless, due to its great durability, there are some environmental and mechanical conditions that can penetrate this barrier and make stainless steel to corrode.

stainless steel rust
stainless steel rust
stainless steel rust
stainless steel rust

stainless steel rust : Causes of Rust in Stainless Steel

His corrosion resistance of stainless steel can sometimes be affected sometimes resulting in rusting of the steel. One major reason for this is the impact of chlorides, for example, in salt. In coastal regions, either due to water splashes or the use of salts for de-icing, the chromium oxide layer that forms on the steel is washed away more often than not. This makes the steel prone to oxidation.Most importantly, any mechanical damage, including scratches, dents, or even disruptions of the passive layer, expose the inner layers of the steel to corrosive agents. Another cause of rusting is through exposure to chemicals. Abrasive cleaners, those with chlorides or bleach, slowly wear away the stainless steel surface’s outer layer. When exposed to high humidity for a longer time or in the presence of moisture in an enclosed space, then that is a perfect recipe for rust to set in. Externally born deposits like dirt, grease, or leftovers of cleaning products can hold moisture on the surface and deepen the corrosion. The other important consideration is the grade of stainless steel. Hence, lower grade steels like 304, are less resistant to rust as compared to higher grades steels like 316. Molybdenum when incorporated into 316 stainless steel offers better protection to chlorides and extreme environments.

Stainless steel rust : Preventing Rust on Stainless Steel

Mechanical maintenance and coating protection measures are major challenges when it comes to avoiding early rust on stainless steel. It is therefore important to select the right grade of stainless steel for each of the applications. For example, 316 stainless steel is recommended when exposed to sea water or a more confined space where acid rain is frequent and corrosive than ordinary meteorological conditions. 304 stainless steel is adequate for the less harsh environments and therefore is quite useful and cost effective for general use. Cleaning and other required care are also important in order to retain the glamour of the stainless steel metal. Rinsing the surface with soap and water also cleans off the surface removing dust, motor oil, and any other dirt that may interfere with the passive film. Again, after washing it is advisable to it properly and make sure that there is no water remaining on the surface because this causes formation of more rusting. Do not use tough scrubbers or chemicals like bleach because they remove special chromium oxide layer and expose it to rust. Furthermore, there is always protection by use of a covering such as stainless steel polish or wax helps prevent moisture and other contaminants. One way in which the amount of exposure can be kept low is use of covers or putting the steel in areas less exposed to chlorides or moisture which causes high corrosion. In critical applications, passivation treatments can chemically improve the chromium oxide layer for a better rust resistance.Electropolishing is also a good way to avoid rusting. This process refines the surface of the stainless steel in order to decrease possible regions of moisture or contaminants concentrations. Electro polishing removes contaminants that reduce adhesion between the articles and between them and their container, and creates a particularly smooth surface that precludes rust formation and affords stainless steel a longer life with the desired shine.

Stainless steel rust : Removing Rust from Stainless Steel

Rust formation on should be removed as soon as possible to avoid the worsening of the situation. First, using only mild soap solution or preferably a cleaner and then using a soft cloth to gently clean the area. It is advisable to use baking soda and water paste as a green solution in the removal of mild rust. Rub the rust with the soft cloth or brush after applying the paste to the area affected by rust. Another type of vinegar that can be advantageous when trying to remove rust contains white vinegar, which is famous for its acidic content. Using white vinegar, damp a cloth and apply it on the rusty area, wash it and dry the surface. If the rust has already set in deeply it will require a commercial rust remover that is intended for use in removing rust from stainless steel as it is very effective. This can be done following the instructions given by the manufacturer to avert ruining the fabric being used. Once corrosion products are eliminated, wash off, and dry the surface area to get back the external covering and minimize future corrosion.

Conclusion

Stainless steel is referred as number one material because it has resistance to rust and corrosion hence very suitable for so many uses. But it is not completely rust resistant and can in fact rust under certain circumstances. Its strength is derived from a thin, passive chromium oxide layer, which shields the steel from oxygen and moisture. That which threatens the stability of this layer include contact with chloride, mechanical abrasion, and use of high chemical cleaners since these bring rust. For instance, water from shorelines or salts used on roads decrease the barrier strength of stainless steel. Scratches and denting affect the outer surface of the steel and allow the inner core steel to wear off from corrosion elements. This is in reference to lower grades such as 304 when placed alongside grade 316 that has incorporated molybdenum to give better rust resistance. Choosing the right grade of stainless steel for the right use eliminates rust. The direct procedures of cleaning by mild soap and water wash off all contaminants that may in one way or the other cause the deterioration of the passive layer. The washing and draining of the surface of the substrate eliminate the chance of development in the amount of the moisture, which plays a great role in corrosion. Not using abrasive scrubbers, or using chemicals such as bleach, will also help to maintain this protective layer. Coating or passivation improves the protection of the material while electro polishing makes the surface free from crevices to allow moisture to accumulate.

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