Is stainless steel really stainless in construction application?

Stainless steel refers to alloy steels with more than 10.5% of chromium and consists of several groups like austenitic, ferritic, martensitic etc. Austenitic stainless steel is normally used in structural applications because of its high corrosion resistance. Austenitic and ferritic types of stainless steel cover about 95% of stainless steel applications. Stainless steel is not stainless although it is corrosion resistant under a wide range of conditions.

A passive layer of chromium oxide is formed on stainless steel’s surface which renders it corrosion resistant. This chromium oxide layer acts as a stiff physical barrier to guard against corrosion and makes it chemically stable. Moreover, when this layer is damaged, it can perform self repairing where there is a sufficient supply of oxygen. However, stainless steel will still corrode by pitting in marine environment where chloride attack occurs.

Therefore, appropriate grades and types of stainless steel have to be selected in polluted and marine environment to minimize the problem of corrosion. Reference is made to Euro Inox and the Steel Construction Institute.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.