Stainless Steel
Stainless steel has a far greater corrosion resistance than normal mild steel. It is used for applications requiring high corrosion 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
- Maintenance
- Life of structure
- Surface finish
Factors, which may influence the selection within an environment, are temperature, pollutants, humidity and presence of chloride ions.
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.
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.