The primary reason for using stainless steel as opposed to either less corrosion resistant alloys or lower cost metals, is for its appearance – specifically it’s appearance in more aggressive environments or for longer-term use.
Stainless steels form a passive layer which protects the underlying metal for corrosion. However, the alloy content required to achieve this phenomenon adds significant cost.
For large-scale applications such as construction cladding or automotive panels, it is possible to provide sufficient corrosion resistance to low-cost carbon steels through a combination of metallic (galvanised) coatings, pre-treatments and paints. The appearance of stainless steels, namely their reflectiveness, may also be unsuitable for many such applications and not provide the level of individual choice possible with coatings.
The use of stainless steels in food preparation areas is an interesting example. The use of protective coatings on basic steel is not viable, due to the likelihood of the coating becoming damaged during use and repeated cleaning, ultimately resulting in corrosion. Subsequently, the aesthetic of stainless steel is associated with clean or hi-tech applications, which has carried across its use in to appliances and building components.
Automotive exhausts represent an application with very corrosive conditions, from road salt during freezing conditions, frequent exposure to rain, and a difficulty of keeping clean encouraging poultice corrosion conditions. Due to the temperatures and thermal cycling experienced by cars, coated steels offer compromised lifetimes. Previously, stainless steels were restricted to higher-performance after-market products, but improvements in stainless steel production with reduced costs opened up the OEM market. Usefully, the passive layer of stainless steels can remain intact at elevated temperatures, the extent of which depends upon the specific grade.
If you have any more questions about our range of high-performance austenitic, duplex and super duplex stainless steels, please contact us today. A member of our team will be more than happy to help and can also advise you on the best option for your application.