Ductile iron, manganese steel, stainless steel, brass, bronze, white copper, solder, hard aluminum, 18K gold, 18K white gold, etc.
Steel
Introduction
Steel is an alloy composed of iron, C, Si, Mn, P, S, and a small amount of other elements. Except for Fe, the content of C plays a major role in the mechanical properties of steel, so it is collectively referred to as iron-carbon alloy. It is the most important and widely used metal material in engineering technology.
Classification and Properties
According to the carbon content, iron-carbon alloys are divided into two categories: steel and cast iron. Steel is an iron-carbon alloy with a carbon content of 0.03% to 2%. Carbon steel is the most commonly used ordinary steel. It is easy to smelt, easy to process, and inexpensive, and in most cases it can meet the requirements of use, so it is widely used. According to the carbon content, carbon steel is divided into low-carbon steel, medium-carbon steel, and high-carbon steel.
As the carbon content increases, the hardness of carbon steel increases and the toughness decreases. Alloy steel, also known as special steel, adds one or more alloying elements to carbon steel, giving it some special properties, such as high hardness, high wear resistance, high toughness, corrosion resistance, etc. Alloying elements frequently added to steel include Si, W, Mn, Cr, Ni, Mo, V, and Ti. China has abundant resources of alloy steel. Except for insufficient Cr and Co and lower Mn grade, the reserves of W, Mo, V, Ti, and rare earth metals are very high.
About Pig Iron
Pig iron is hard and brittle, but it is pressure and wear resistant. Gray iron and ductile iron. In white cast iron, carbon is in the form of Fe3C, the fracture is silvery white, it is hard and brittle, and cannot be mechanically processed. It is a raw material for steelmaking, so it is also called steelmaking pig iron.
If carbon is distributed in the form of flake graphite, it is called gray iron, the fracture is silver-gray, easy to cut, easy to cast, and wear-resistant. If carbon is distributed in the form of spherical graphite, it is called ductile iron, and its properties and processing properties are close to steel. Adding special alloying elements to cast iron can produce special cast iron. For example, adding Cr can greatly improve wear resistance, which has very important applications under special conditions.
Ferrosilicon
Ferrosilicon is made by smelting coke, steel shavings, and quartz (or quartzite) in an electric furnace. Silicon and oxygen are easily combined to form silicon dioxide. Therefore, ferrosilicon is often used as a deoxidizer in steelmaking. At the same time, because a large amount of heat is released when SiO2 is generated, it is also beneficial to increase the steel temperature during deoxidation. Ferrosilicon is added as an alloying element.
It is widely used in low-alloy structural steel, alloy structural steel, spring steel, bearing steel, heat-resistant steel, and electrical silicon steel. In addition, ferrosilicon is often used as a reducing agent in ferroalloy production and the chemical industry. The silicon content reaches 95%--99%. Pure silicon is often used to manufacture single-crystal silicon or prepare non-ferrous metal alloys.
Ferromanganese
Ferromanganese is made from manganese ore. It is smelted in a blast furnace or electric furnace. Ferromanganese is also a commonly used deoxidizer in steel. Manganese also has the effect of desulfurization and reducing the harmful effects of sulfur. Therefore, almost all steels and cast irons contain a certain amount of manganese. Ferromanganese is also an important alloying agent. It is widely used in structural steel, tool steel, stainless heat-resistant steel, and wear-resistant steel.
Aluminum Alloy
Introduction
Aluminum is a widely distributed element. Its content in the earth's crust is second only to oxygen and silicon, and it is the highest among metals. Pure aluminum has a low density of 2.7 g/cm3, good thermal and electrical conductivity (second only to Au, Ag, Cu), good ductility, and high plasticity, and can be subjected to various mechanical processing. Aluminum is chemically active and quickly oxidizes in air to form a dense and strong oxide film, thus having good corrosion resistance. However, pure aluminum has low strength, and various aluminum alloys that can be used as structural materials can only be obtained through alloying.
Characteristics and Properties
The outstanding characteristics of aluminum alloys are their low density and high strength. Al-Mn and Al-Mg alloys formed by adding Mn and Mg to aluminum have good corrosion resistance, good plasticity, and high strength. They are called rust-proof aluminum alloys and are used to manufacture fuel tanks, containers, pipelines, rivets, etc. The strength of hard aluminum alloys is higher than that of rust-proof aluminum alloys, but the corrosion resistance is reduced. These alloys include Al-Cu-Mg series and Al-Cu-Mg-Zn series. Recently developed high-strength hard aluminum has further improved strength, while the density is reduced by 15% compared to ordinary hard aluminum, and it can be extruded, and can be used as components such as motorcycle frames and wheel rims. Al-Li alloys can be used to make aircraft parts and high-end sports equipment that bear loads.
Applications
High-strength aluminum alloys are widely used in the manufacture of aircraft, ships, and heavy-duty vehicles, which can increase their load capacity and improve operating speed, and have characteristics such as resistance to seawater erosion and anti-magnetism.
Copper Alloy
Introduction
Pure copper is purplish red, so it is also called purple copper. It has excellent thermal and electrical conductivity, and its electrical conductivity is second only to silver among metals. Copper has excellent chemical stability and corrosion resistance, and is an excellent electrical metal material.
Classification
Copper alloys widely used in industry include brass, bronze, and white copper.
Alloys of Cu and Zn are called brass, in which Cu accounts for 60% to 90% and Zn accounts for 40% to 10%. They have excellent thermal conductivity and corrosion resistance and can be used as various instrument parts. For example, adding a small amount of Sn to brass is called naval brass, which has good resistance to seawater corrosion. Adding a small amount of Pb with lubricating properties to brass can be used as a sliding bearing material.
Bronze is the oldest metal material used by humankind; it is a Cu-Sn alloy. The addition of tin significantly improves the strength of copper, enhances its plasticity, and increases its corrosion resistance. Therefore, tin bronze is often used to manufacture wear-resistant parts such as gears and corrosion-resistant accessories. Since tin is expensive, it has been largely replaced by Al, Si, and Mn to obtain a series of bronze alloys. Aluminum bronze has even better corrosion resistance than tin bronze. Beryllium bronze is the strongest copper alloy; it is non-magnetic and has excellent corrosion resistance, making it a spring material that can compete with steel.
Nickel silver is a Cu-Ni alloy with excellent corrosion resistance and high electrical resistance, so it can be used as a material for components and resistors operating under harsh corrosive conditions.
Brass contains zinc and small amounts of tin, lead, aluminum, etc.