Certified Ophthalmic Medical Technologist (COMT) Practice Exam

Which element is primarily responsible for enhancing the corrosion resistance of stainless steel instruments?

1. Nickel

2. Carbon

3. Chromium

4. Iron

The correct answer is: Chromium

The primary element responsible for enhancing the corrosion resistance of stainless steel instruments is chromium. When chromium is added to the alloy, it forms a passive layer of chromium oxide on the surface of the steel. This oxide layer acts as a protective barrier that prevents further oxidation and corrosion of the underlying metal. The presence of at least 10.5% chromium is what classifies the steel as “stainless,” signifying its enhanced resistance to rust and corrosion compared to regular carbon steel. While nickel can also contribute to corrosion resistance and improve the overall toughness and ductility of stainless steel, it is not the primary element responsible for the corrosion-resistant properties. Carbon, on the other hand, is an element that can increase hardness and strength but may also make stainless steel more prone to corrosion if not balanced properly with other alloying elements. Iron is the base metal in stainless steel, but it does not provide corrosion resistance on its own; rather, its presence can lead to rust formation if not adequately alloyed with chromium and other elements. Thus, chromium stands out as the key element in providing the essential characteristic of corrosion resistance in stainless steel instruments.