Steel casting
Steel casting is a special form of casting that involves different steels. Steel casting is used when cast iron cannot have sufficient strength or impact resistance
Steel, an alloy of iron and carbon in which the carbon content is up to 2% (with a higher carbon content, the material is defined as cast iron). Until now, the material is widely used for construction in the world of infrastructure and industry. , it is used to make everything from sewing needles to oil tankers. In addition, the tools required to make and manufacture such articles are also made of steel.
As an indication of the material's relative importance, in 2013 world crude steel production was about 1.6 billion tons, while production of the next most important engineering metal, aluminum, was about 47 million tons.
The main reasons for the popularity of steel are the relatively low cost of its production, formation and processing, the abundance of its two primary materials (iron ore and scrap), and the unique range of mechanical properties.
Steel is an alloy metal whose main components are iron and carbon between 0.02 and 1.7 percent by weight. Carbon is an alloying element for iron, but many other alloying elements are also used in steel.
Carbon and other elements act as a hardening agent and prevent dissociation in the iron atom and crystallize the so-called network. The difference in the amount of alloy elements and their distribution in steel controls qualities such as hardness, elasticity, flexibility and tensile strength of steel and its other properties. For example, steel can become harder and stronger than iron by increasing carbon, but it also becomes more brittle. Before steel production, according to the required properties, the steel alloy is selected according to the standard.
The maximum carbon content of steel is approximately 0.75%, and also the maximum solubility of carbon in iron is 1.7% by weight, which occurs at 1130 °C. Higher concentrations of carbon or low temperatures cause the production of cementite, which reduces the strength of the material.
Properties of steel (steel)
The main component of steel is iron, a metal that is not much harder than copper in its pure state. In its solid state, iron, like all other metals, is polycrystalline—that is, it is made up of many crystals that join together at their boundaries.
Hardness: The ability of a material to resist wear. The carbon content determines the maximum hardness achievable in the steel.
Strength-strength: the amount of force required to change the shape of a material. Higher carbon content and hardness result in higher strength steel.
Ductility: The ability to change the shape of a metal under tensile stress. Low carbon content and lower hardness result in steel with higher ductility.
Toughness: the ability to withstand mental pressure. Increased ductility is usually associated with better toughness. Hardness can be adjusted by adding alloying metals and heat treatment.
Abrasion resistance: A material's resistance to friction and wear. Cast steel exhibits similar wear resistance to forged steels of similar composition. Adding alloy elements such as molybdenum and chromium can increase the wear resistance.
Corrosion resistance: the material's resistance to oxidation and rust. Cast steel exhibits similar corrosion resistance to wrought steel. High alloy steels with high levels of chromium and nickel are highly resistant to oxidation.
Machinability: The ease with which a steel casting can be deformed by removing material through machining (cutting, grinding, or drilling). Machinability is affected by hardness, strength, thermal conductivity and thermal expansion. Weldability: The ability to weld steel without defects. Weldability primarily depends on the chemical composition of the steel casting and heat treatment.
High Temperature Properties: Steels operating at temperatures above ambient are subject to degraded mechanical properties and early loss due to oxidation, hydrogen damage, sulfite scaling, and carbide instability.
Low temperature properties: The strength of cast steel is greatly reduced at low temperatures. Alloy and specialized heat treatments can improve the casting's ability to withstand loads and stresses.
The chemical composition of the cast steel
The chemical composition of cast steel has a significant effect on performance and is often used to classify steel or determine standard specifications. Cast steels can be divided into two broad categories: carbon cast steel and alloy steel.
Carbon steel castings: Like forged steels, carbon steel castings can be classified according to their carbon content. Low carbon cast steel (0.2% carbon) is relatively soft and not easily heat treated. Cast steel with medium carbon (0.2-0.5% carbon) is somewhat harder and can be strengthened by heat treatment. High carbon cast steel (0.5% carbon) is used if maximum hardness and wear resistance is desired.
Carbon steel castings: Like wrought steels, carbon steel castings can be classified according to their carbon content. Low carbon cast steel (0.2% carbon) is relatively soft and not easily heat treated. Cast steel with medium carbon (0.2-0.5% carbon) is somewhat harder and can be strengthened by heat treatment. High carbon cast steel (0.5% carbon) is used if maximum hardness and wear resistance is desired.
Alloy steel castings: Alloy steel castings are classified as low or high alloy. Low-alloy cast steel (≤ 8% alloy content) behaves similarly to conventional low-carbon steel, but with higher hardenability. High alloy casting steel (>8% alloy content) is designed to produce a specific property such as corrosion resistance, heat resistance or wear resistance.
High alloy steels are stainless steel (> 10.5% Cr) and Hadfield Manganese steel (11-15% Mn). The addition of chromium, which forms an active layer of chromium oxide when exposed to oxygen, gives stainless steel excellent corrosion resistance. Manganese content in Hadfield steel provides high wear resistance during hard work.