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This post was last edited by Wang Wei2 on 2020-6-26 at 10:08. What is stainless steel? The main alloying elements of stainless steel are chromium, molybdenum, nickel, and nitrogen. Chromium forms a passivating chromium oxide protective film; the corrosion resistance of stainless steel stems from this surface oxide film. It is a ferritic stainless steel containing FeCr, with grades such as 430-type stainless steel ； Nickel stabilizes austenite, endowing it with ductility, toughness, and weldability; it forms austenitic stainless steels such as 304 stainless steel ； Molybdenum provides resistance to pitting and crevice corrosion; it is suitable for marine environments as well as industrial atmospheric conditions, with steel grades such as 316 stainless steel ； Nitrogen also provides stability to austenite, resistance to pitting and crevice corrosion, as well as improved strength properties; examples of steel grades include 2205 duplex stainless steel. Why is stainless steel used in construction? One reason is to meet the needs of modern society: it enhances the value of a product. The unique design or appearance of stainless steel enables it to secure a certain position in the market. It requires minimal maintenance or refurbishment costs. Stainless steel also has the least environmental impact during manufacturing, use, and disposal, and it can help increase profits as well. In terms of the properties of stainless steel itself: it is corrosion-resistant, does not require painting, has a high-quality appearance, comes in a variety of surface finishes and styles, possesses high strength, is easy to manufacture and weld, allowing it to be shaped into various complex forms. Additionally, it can be recycled 100%. Stainless steel is sometimes the most cost-effective option, usually with higher initial costs but lower life-cycle costs. The stainless steel grades used in construction and structures include: ferritic, austenitic, and duplex (ferritic-austenitic). Unlike carbon steel, stainless steel rarely fails due to uniform corrosion; if it does fail, it is as a result of localized corrosion, such as pitting and crevice corrosion. In construction, failure is generally of an aesthetic nature rather than structural, and a corrosion allowance is meaningless in this context. Technical issues to consider for stainless steel include, first, in terms of design, simple shapes should be used to facilitate cleaning, gaps should be avoided to prevent dirty water from splashing, and cleaning inlets should be employed to avoid adverse galvanic effects (contact between different metals) ； Secondly, regarding the choice of steel grade, 430 or 304 is generally used for internal applications; for external applications where the requirements are not as strict (in rural areas), 316 can be used. In harsh marine or industrial environments, smooth 316 stainless steel that requires frequent cleaning is employed, as well as steel grades with higher alloy contents such as 317 stainless steel, 2205 duplex stainless steel, and 6% Mo stainless steel. Of course, the specific material to be used should be determined based on the actual conditions at the site.