**1. Introduction**

Stainless steels (iron-based alloys) are widely recognized due to their high machinability, hardness, mechanical strength, good heat resistance and excellent corrosion resistance [1–3]. Compared to other steels, the superior corrosion resistance exhibited by many stainless steels can be attributed to the chromium content (about 10.5 wt.%) which initiated the formation of a stable layer of chromium oxide on the steel surface [2, 3] thereby preventing chemical reactions with the bulk material hence reducing corrosion attack to the minimum. Chromium is one of the major elements that play a vital role in the corrosion resistance of stainless steels. However, when exposed to water for a long period, their corrosion resistances reduce at elevated temperatures, hence the need to come up with more robust techniques for protecting the sample surface.

Even though they exhibit good corrosion resistance, efforts have continually been made to further improve the corrosion resistance behaviour of stainless steels. Heat treatment such as annealing due to the oxidation of steel surface [4–6], surface mechanical treatment [7–12], coatings/electrodepositions [13–16], alloying, machining/molding [17] and many more are presently in use to further improve the corrosion resistance behaviour of stainless steels. Other protection methods include epoxy coating, cathodic protection, and thicker concrete cover. For instance, surface modifications, as well as heat treatments of the modified sample surface

by low temperature annealing, were used to enhance the corrosion resistance of 301, 17-4PH, 304 steels, 316, and mild steels [4, 5, 9, 12]. To sum it up, stability, compaction, chemical composition, thickness, and many more are the main factors influencing the corrosion resistance of stainless steels [18–20].

In the present study, the general overview of stainless steels including their properties and application is presented. The corrosion resistance of stainless steel and evaluation methods are evaluated. The surface treatment methods aimed at enhancing the overall corrosion and mechanical properties are then presented.
