Final answer:
Chromium is commonly found in the coatings of several types of welding fluxes due to its ability to form a protective oxide layer that prevents corrosion.
Step-by-step explanation:
Among the options provided - chromium, asbestos, lead, and cadmium - the substance commonly found in welding flux coatings is chromium. This is because one of the techniques used to prevent corrosion is applying a thin layer of chromium using an electrolytic process. Chromium is used due to its ability to create a protective oxide layer that hinders access of oxygen and water to the underlying material. Along with its use in coatings, chromium compounds like chromium(III) oxide are also known in various industrial applications.