Hmmm, PhilBY, the entire sink is made of stainless, at least here in the U.S. Stainless steel is always made using chromium. The minimum amount of chromium used to make stainless steel is 10.5%; it is chromium that makes the steel stainless. Chromium also improves the corrosion resistance by forming a chromium oxide film on the steel. This very thin layer, when placed under the right conditions, can also be self-repairing.
There are other elements used to make stainless steel as well, including nickel, nitrogen and molybdenum. Bringing these elements together forms different crystal structures that enable a variety of properties in machining, welding and forming. It's this mixture of metals that must provide the odor removing properties I've noted.
There are four major types of stainless steel. Of these, austenitic is the most widely used type. It has a nickel content of at least 7%, which makes it very flexible. It is used in a range of houseware products, industrial piping and vessels... there are other kinds as well, depending on the percentage of metals used...