Common steel grades and uses
Steel is a metallic material primarily composed of iron, typically containing less than 2% carbon, and containing other elements. Steel can be classified into many types based on its chemical composition, mechanical properties, and intended use. Each type of steel has its own specific grade and application. The following describes several common steel grades and their uses.
Carbon structural steel is one of the most commonly used steel grades. Its designation consists of the letter “Q” representing the yield point, the yield point value, the quality grade symbol, and the deoxidation method symbol. For example, Q235 steel is a common carbon structural steel. “Q” represents the yield point, and “235” indicates a yield point value of 235 MPa. The quality grades are A, B, C, and D, with D being the highest quality. Q235 steel has good plasticity and toughness, excellent weldability, and is inexpensive. It is widely used in construction, bridges, ships, vehicles, and machinery manufacturing, such as in the manufacture of structural steel components, steel plates, sections, bolts, and nuts. In addition, there are carbon structural steels of grades such as Q195, Q215, Q255, and Q275. Their yield points are different and their uses are also different. Q195 and Q215 steels with lower yield points are often used to manufacture thin plates, iron wires, etc.; Q255 and Q275 steels with higher yield points are often used to manufacture parts with higher strength requirements, such as chains, gears, etc.
High-quality carbon structural steel grades are designated by two digits, representing the steel’s average carbon content in parts per ten thousand. For example, 45 steel indicates an average carbon content of 0.45%, while 20 steel indicates an average carbon content of 0.20%. High-quality carbon structural steels have low sulfur and phosphorus contents, excellent mechanical properties, and can be strengthened through heat treatment. 45 steel is a widely used, high-quality carbon structural steel. It offers high strength and hardness, along with reasonable plasticity and toughness. It is often used in the manufacture of gears, shafts, connecting rods, and other parts requiring a good balance of strength and toughness. After quenching and tempering, its overall mechanical properties are further enhanced. 20 steel is a low-carbon, high-quality carbon structural steel with excellent plasticity, toughness, and weldability. It is commonly used in the manufacture of stamped parts, welded structural components, and parts requiring carburizing, such as bearing rings and gears. Carburizing results in high surface hardness, excellent wear resistance, and core toughness.
Alloy structural steel is a type of steel created by adding one or more alloying elements (such as chromium, nickel, manganese, molybdenum, and silicon) to carbon structural steel. Its designation consists of a two-digit number followed by the element symbol and a number. The two-digit number represents the average carbon content in parts per thousand of the steel, the element symbol identifies the alloying element, and the number represents the average content of the alloying element (the number can be omitted if the alloying element content is less than 1.5%). For example, 40Cr steel indicates an average carbon content of 0.40% and a chromium content of less than 1.5%. 20CrMnTi steel indicates an average carbon content of 0.20% and chromium, manganese, and titanium content of less than 1.5%. Alloy structural steel exhibits high comprehensive mechanical properties, including strength, hardness, toughness, and wear resistance, and is widely used in machinery manufacturing, aerospace, and automotive industries. 40Cr steel is a commonly used alloy structural steel. After quenching and tempering, it has good comprehensive mechanical properties and is often used to manufacture important parts such as shafts, gears, and connecting rods. 20CrMnTi steel is a carburizing steel. After carburizing, it has high surface hardness, good wear resistance, and good core toughness. It is often used to manufacture gears and other parts in automobiles and tractors.
Tool steel is a type of steel used to manufacture various tools. Depending on its intended use, it can be categorized as cutting tool steel, die steel, and gauge steel. Tool steel grades are typically designated as “T” followed by a number, where “T” stands for tool steel and the number represents the steel’s average carbon content in parts per thousand. For example, T10 steel indicates an average carbon content of 1.0%. Cutting tool steel requires high hardness, high wear resistance, and a certain degree of toughness. It is commonly used in the manufacture of cutting tools such as turning tools, milling cutters, and drill bits. T10 steel is a commonly used cutting tool steel. After quenching and tempering, it can reach a hardness of HRC 60-65. It offers good wear resistance but relatively low toughness, making it suitable for manufacturing tools used in low-speed cutting. Mold steel can be divided into cold-work die steel and hot-work die steel based on its application. Cold-work die steel, such as Cr12 steel, is used to manufacture dies for cold stamping and cold extrusion, and requires high hardness, wear resistance, and hardenability. Hot-work die steel, such as 5CrNiMo steel, is used to manufacture dies for hot forging and hot extrusion, and requires high high-temperature strength, toughness, and wear resistance. Gauge steel, such as CrWMn steel, is used to manufacture various measuring tools, such as calipers and micrometers, and requires high hardness, wear resistance, and dimensional stability.
Special performance steels, such as stainless steel, heat-resistant steel, and wear-resistant steel, are grades with exceptional physical and chemical properties. Stainless steel is corrosion-resistant and is typically designated by grades like “0Cr18Ni9” and “1Cr13,” where “0” indicates a carbon content of less than 0.08%, “1” indicates a carbon content of 0.08%-0.15%, and “Cr18Ni9” indicates an 18% chromium and 9% nickel content. 0Cr18Ni9 is a commonly used austenitic stainless steel with excellent corrosion resistance and plasticity, making it widely used in food processing, medical equipment, chemical containers, and other fields. Heat-resistant steels, such as 1Cr18Ni9Ti steel, exhibit high strength and oxidation resistance at high temperatures and are commonly used in the manufacture of components for high-temperature equipment such as boilers and steam turbines. Wear-resistant steel is a type of steel with high wear resistance, such as ZGMn13 steel. When subjected to strong impact wear, its surface will quickly undergo work hardening, forming a hard wear-resistant layer, while the core still maintains good toughness. It is often used to manufacture parts that are subjected to impact wear, such as excavator buckets and railway switches.
