What is a ferrous metal and non-ferrous metal?
Ferrous metal is any metal containing iron, including steel and cast iron. It’s used in construction, automobiles, and manufacturing due to its strength and durability.
Non-ferrous metal is any metal that does not contain iron, such as aluminum, copper, lead, nickel, tin, and zinc.
Difference between Iron and Steel
Iron is a metal that is generally found in nature in the form of ore, which is melted and processed to extract the pure metal. Iron is a relatively soft metal, which makes it easy to work with but also makes it vulnerable to rust and other forms of corrosion.
Steel is an alloy made by combining iron and other elements, such as carbon, silicon, and phosphorus. It is much stronger and more durable than iron. The main difference between steel and iron is the amount of carbon present in each. Iron is an element and can be found in pure form, whereas steel is an alloy made from iron and other elements such as carbon. Steel typically contains anywhere from 0.2-2.1% carbon, while iron usually contains 0.008-0.04% carbon. Steel also has a significantly higher tensile strength and yield strength than iron.
What is the steel number mean?
Each type of steel is assigned with a number which is also known as steel grades. They refer to the standard grades given to different types of steel based on their composition and properties. Steel numbers are important for specifying the type of steel to be used in a particular application. Common steel number systems include ASTM, AISI, UNS, and SAE.
Understand the ASTM, AISI, UNS, and SAE standards
AISI: The American Iron and Steel Institute (AISI) is a trade association that represents the steel industry in the United States. AISI stands for American Iron and Steel Institute. It provides a standard for steel grades and specifications. AISI standard is mainly used in USA.
ASTM: The American Society for Testing and Materials (ASTM) is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services. ASTM standards cover a wide range of materials, including metals, plastics, rubber, and textiles. ASTM standard is used world widely.
UNS: The Unified Numbering System (UNS) is a system for standardizing the chemical compositions of metals and alloys. It assigns a unique 4-digit number to each alloy, which identifies its chemical composition. The UNS system is used by the American Society for Testing and Materials (ASTM) and the Society of Automotive Engineers (SAE) to identify metals and alloys.
SAE: The Society of Automotive Engineers (SAE) is an international standards organization that develops and publishes technical standards for the automotive industry. SAE standards cover a wide range of topics, including vehicle design, materials, components, and testing.
Introduce different type of steel:
Carbon steels are plain carbon steels that are alloyed with other elements to enhance their mechanical properties. There are four main types of carbon steels: low carbon (or mild) steel, medium carbon steel, high carbon steel, and ultra-high carbon steel.
Low Carbon Steel
Low carbon steel (for example: ASTM A36/A36M) contains up to 0.3% carbon and is the most common grade of carbon steel that is commonly used in structural applications. This steel is easily machinable, weldable, and has good formability. It is commonly used for general structural purposes such as bridges and buildings.
Medium Carbon Steel
Medium Carbon Steel (for example: ASTM A830-1045) contains between 0.3–0.6% carbon and is stronger than low carbon steel, but more difficult to shape and form. It is commonly used for parts that require strength and durability, such as bolts, gears, cams, and shafts. This steel has good machinability, weldability, and formability properties.
High Carbon Steel
High Carbon Steel (for example: ASTM A830-1060) contains up to 2.1% carbon and is very strong, ductile, and heat treatable which is commonly used in production of tools, blades, and other components requiring high strength and wear resistance.
Ultra High Carbon Steel
Ultra High Carbon Steel (for example: ASTM A830-1095) contains up to 2.5% carbon and can be hardened and tempered to create a strong and durable material. It has excellent wear resistance and toughness and is commonly used for tools and dies.
Alloy steel is an alloy consisting primarily of iron, with added elements such as chromium, manganese, molybdenum, nickel, etc., to improve its properties. Alloy steels are generally stronger and harder than carbon steel and are more difficult to shape and form. They are often used in applications that require strength or corrosion resistance.
Low Alloy Steel
The widely used low alloy steel are AISI 4140 and AISI 4130. AISI 4140 (Chromium-Molybdenum Steel) is used for a variety of applications including axles, shafts, bolts, and gears. AISI 4130 are similar to 4140 but with lower carbon content and better weldability. AISI 4130 is used in a variety of applications, including oil and gas, chemical, and aerospace.
High Alloy Steel
High alloy steel are wildly known as stainless steel. AISI 304 and AISI 316 are two very common stainless steel. The main difference between 304 vs 316 stainless steel is the composition and corrosion resistance, 304 doesn’t contain molybdenum while 316 contains 2-3% molybdenum. Also, 304 has 18% chromium and 8% nickel content while 316 has 16% chromium and 10% nickel. The molybdenum addition increases the corrosion resistance of 316 stainless steel, especially against pitting and crevice corrosion in chloride environments. 304 is commonly seen in kitchen hardware where contacts fresh water, while 316 is widely used in offshore applications.
CRA (Corrosion Resistant Alloys) Steel:
The widely known CRA is Inconel alloy. Inconel alloy is widely used in high temperature and high corrosive environments where high strength requires. Inconel alloys are designated by their chemical composition, such as Inconel 600 (NiCr15Fe) or Inconel 718 (NiCr19Fe19Nb).
Special Purpose Steel:
Tool steel is a type of steel used in making tools because of its high hardness and abrasion resistance. It often contains tungsten, molybdenum, chromium, and vanadium. Common tool steel include A2, A5, D2, H13, and S7. A2 and A5 are air-hardening, medium-alloy, cold-work steels with good wear resistance. D2 is a high-carbon, high-chromium, air-hardening tool steel, heat treatable to a hard, wear-resistant and tough state. H13 is a hot-work tool steel with the addition of chromium and molybdenum for improved toughness and wear resistance. S7 is an air-hardening, shock-resisting tool steel with excellent toughness and good machinability. These tool steels are commonly used in the manufacturing of cutting tools, dies, punches, and other metalworking tools.
High-speed is a type of tool steel that contains tungsten, molybdenum, and cobalt, and is used for cutting tools due to its high heat resistance and ability to stay sharp. The common high speed steel number is M2, and it is used for cutting tools, drills, reamers, taps, end mills, and other cutting applications.