The names “ferrous metals” and “nonferrous metals” often lead people to misunderstand that ferrous metals must be black, but this is not the case.
Some junior and senior high school textbooks define ferrous metals and nonferrous metals as follows: Ferrous metals consist of iron, manganese, chromium, and other metals that are not included in this category are referred to as nonferrous metals.
Related reading: Ferrous vs Non-ferrous Metals: What’s Their Difference?
It is apparent that iron, manganese, and chromium are not black. Pure iron has a silver-white color, chromium is silver-white, and manganese is off-white.
However, despite their color, they are considered ferrous metals. In industrial applications, parts and tools made from iron and iron alloys do not have a smooth surface, which results in their inability to reflect light perfectly. They absorb part of the light spectrum, causing their surfaces to appear darkened, which is known as diffuse reflection.
Therefore, all metal materials, including iron and iron alloys, are traditionally referred to as ferrous metals. Iron alloys are often blended with manganese and chromium, which are also classified as ferrous metals.
The following is a discussion on black iron powder commonly used in physical experiments.
In foreign literature, the terms “ferrous metal” and “nonferrous metal” are commonly used to refer to metals that either contain or do not contain iron, respectively.
The term “ferrous” specifically refers to materials that contain iron.
To be more precise, “ferrous metal” is the full name used to describe various metal materials that contain iron, including pig iron or ferroalloy steel.
On the other hand, “nonferrous metals” are those that either do not contain iron or contain only negligible amounts of it.