What are the common engineering materials and metal materials?

The metal materials used in engineering are mainly alloys, and pure metals are rarely used, because alloys have better mechanical properties and technological properties than pure metals, and their prices are low. The most commonly used alloys are iron-carbon alloys based on iron, such as carbon steel, alloy steel and cast iron, and brass and bronze based on aluminum or copper.

(1) ferrous metal.

① Carbon steel: Carbon steel refers to an iron-carbon alloy with the mass fraction of carbon less than 2. 1 1% and a small amount of impurity elements such as silicon, manganese, sulfur and phosphorus, which is called carbon steel for short. The properties of carbon steel mainly depend on carbon content. The higher the carbon content, the higher the general strength and hardness and the lower the toughness. According to the different carbon content, there are several kinds of steel. For example, steel with 0.45% carbon mass fraction is called 45 steel, and steel with 0.35% carbon mass fraction is called 35 steel. Manganese and silicon in carbon steel are beneficial elements, which has a certain strengthening effect on steel; Sulfur and phosphorus are harmful elements that increase the hot brittleness and cold brittleness of steel respectively and should be strictly controlled.

(2) Alloy steel: In order to improve the properties of steel, steel with other alloying elements added on the basis of carbon steel is called alloy steel. Commonly used alloying elements are silicon, manganese, chromium, nickel, copper, vanadium, titanium and rare earth elements. Alloy steel has good special properties, such as low temperature resistance, corrosion resistance, high magnetism and high wear resistance. It is often used to manufacture tools or large-section parts with high mechanical and technological performance requirements and complex shapes, and has been widely used to manufacture parts with special performance requirements.

③ Cast iron: Iron-carbon alloy with carbon content greater than 2. 1 1% is called cast iron. Because cast iron contains more carbon and impurities, its strength and hardness are worse than steel, so it can't be forged. However, cast iron is the most widely used metal material in machinery manufacturing because of its excellent castability, shock absorption and wear resistance, low price and simple production equipment and technology. It is suitable for obtaining cast iron blank by casting.

(2) Non-ferrous metals.

Generally, iron and its alloys are called ferrous metals, while aluminum, magnesium, copper, zinc and their alloys are called nonferrous metals. There are many kinds of nonferrous metals. Although their output and application range are not as good as ferrous metals, they have become indispensable materials in modern industry because of their special properties. For example, aluminum and aluminum alloys are widely used in aviation, aerospace, electronics industry and daily necessities.