6?1 What are common metal materials, including alloys? How to recognize them?

Metal materials are usually divided into ferrous metals, non-ferrous metals and special metal materials. ① ferrous metals, also known as iron and steel materials, including industrial iron containing more than 90% of iron, cast iron containing 2% to 4% carbon, carbon steel containing less than 2% carbon, as well as a variety of uses of structural steel, stainless steel, heat-resistant steel, high-temperature alloys, precision alloys and so on. Ferrous metals in a broad sense also includes chromium, manganese and its alloys. ② non-ferrous metals refers to all metals and their alloys except iron, chromium, manganese, usually divided into light metals, heavy metals, precious metals, semi-metals, rare metals and rare earth metals. The strength and hardness of non-ferrous alloys are generally higher than that of pure metals, and the resistance is large and the resistance temperature coefficient is small. ③ Specialty metal materials include structural and functional metal materials for different purposes. Among them, there are amorphous metal materials obtained through rapid condensation process, as well as quasi-crystalline, microcrystalline, nanocrystalline metal materials, etc.; there are also stealth, anti-hydrogen, superconductivity, shape memory, wear-resistant, vibration damping and other special functional alloys, as well as metal matrix composite materials. Identification methods: most of the naked eye can be initially determined in addition to the physical properties of various materials, chemical properties can be further identified. To give an example, iron, magnetic, with a magnet can be identified. Different materials have different properties, not explained here. You can check the nature of different substances in books or websites.