Stainless steel has a far greater corrosion and heat resistance than normal mild steel. It is used for applications requiring high corrosion resistance, heat resistance or extended life. It is an increasingly popular construction material with its whole life cost benefits contributing to towards more sustainable development.
Stainless Steel is a group of steels containing a minimum of 10.5% chromium where corrosion resistance is determined by the amount of chromium and the addition of alloys such as nickel, manganese and molybdenum.
The formation of a stable, passive oxide film on the surface provides stainless steel with a corrosion protection layer. The film forms rapidly by the alloy elements in the steel, mainly chromium, nickel and molybdenum, reacting with water and air. Stainless steel is available in several different grades, each grade containing varying percentages of alloys used to provide the material with physical properties such as strength, corrosion resistance, welding, machining, etc.
The selection of the correct grade of stainless steel must take account of the following features:
- The environment
- Structural requirements
- Life of structure
- Surface finish
Factors, which may influence the selection within an environment, are temperature, pollutants, humidity and presence of chloride ions.
Civil Engineering and Geotechnical
Stainless UK Ltd stock the two main grades of stainless steel used in construction.
Grade 304 (1.4301) is the grade most often used for corrosion resistant reinforcement, suitable for most atmospheric and concrete covered environments.
Grade 316 (1.4436) has a higher molybdenum and nickel content than 304 (1.4301). It is more expensive but also has higher corrosion resistance and is the recommended grade for marine and corrosive environments.
Although the chemical composition and corrosion resistance are different, the physical properties of the 2 grades are similar.
Heat Resistant and Corrosion Resistant Steel and Products
In addition to Grades 304 and 316, Stainless UK can supply the following grades for heat and corrosion resistant applications requiring stainless steel products to function at temperatures up to 1200°C or corrosive environments.
Grade 310 (1.4845) is a heat resisting steel with excellent resistance to corrosion and oxidisation at high temperatures.
Grade 321 (1.4541) is stabalised with titanium to prevent weld decay. It combines good resistance to oxidisation with strength at elevated temperatures.
Inconel 601 (2.4851) is a nickel chromium heat resistant alloy with excellent performance up to about 1200°C. It has good strength and toughness at extended high temperatures.
Inconel 625 (2.4856) is a nickel, chrome molybdenum alloy with high strength at elevated temperatures and excellent corrosion resistance.
Stainless steel continues to grow in popularity as a construction material with more contractors and engineers appreciating the materials benefits in terms of whole life costing and contribution towards more sustainable development.
The initial costs of using stainless steel are high but they can be cheap when compared to the costs that can be incurred due to premature failure or need for repair or replacement due to corrosion.
The greatly extended life of stainless steel reduces the need to repair and replace structures so saving on future energy consumption. At the end of its life stainless steel is 100% recyclable.