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1. The pump body is made of gray cast iron. It has a high carbon content (2.7%–4.0%), with carbon existing primarily in the form of flake graphite; its fracture surface is gray, hence it is also known as gray cast iron. It has a low melting point (1145–1250°C), experiences little shrinkage during solidification, its compressive strength and hardness are similar to those of carbon steel, and it offers good shock absorption. Used to manufacture structural components such as machine tool beds, cylinders, and enclosures. 2. White cast iron. The carbon and silicon contents are low; carbon exists mainly in the form of cementite, and the fracture surface is silver-white in color. It contracts significantly during solidification, making it prone to shrinkage cavities and cracks. It has high hardness and high brittleness, and cannot withstand impact loads. It is often used as blanks for malleable cast iron and to manufacture wear-resistant components. 3. Malleable cast iron. It is obtained by annealing white cast iron, with graphite distributed in agglomerate form; it is also referred to as ductile iron. It has uniform mechanical properties, is wear-resistant, and possesses good plasticity and toughness. Used to manufacture parts with complex shapes that can withstand high dynamic loads. 4. Ductile iron. It is obtained by spheroidizing gray cast iron molten metal, resulting in spherical graphite particles; it is commonly referred to as spheroidal cast iron. It has higher strength, as well as better toughness and plasticity compared to ordinary gray cast iron. Used in the manufacture of internal combustion engines, automotive parts, and agricultural machinery, etc. 5. Nodular cast iron. It is obtained by creep treatment of gray cast iron melt, with the precipitated graphite appearing worm-like. Its mechanical properties are similar to those of ductile iron, while its castability lies between that of gray cast iron and ductile iron. Parts used in manufacturing cars. 6. Alloy cast iron. I. Cast Iron: Gray cast iron is the most commonly used type of cast iron. It is generally used for the pump body, impeller, pump cover, suspension components, etc., in clean water pumps, with three different grades being typically utilized. Ductile iron is a type of cast iron with good comprehensive properties. Due to its mechanical properties being similar to those of steel, along with superior casting and machining properties compared to steel, it is often used as a substitute for cast steel. Due to constraints such as casting, the company is not currently producing this material. II. Stainless Steel: The most widely used type of stainless steel is austenitic stainless steel. Except for a few media such as hydrochloric acid and dilute sulfuric acid, austenitic stainless steel is an excellent corrosion-resistant material and is the most commonly used corrosion-resistant material in chemical pumps. Additionally, high-alloy stainless steels ( alloy 20 ) and duplex stainless steels are also ideal corrosion-resistant materials. III. Cast steel: The strength of cast steel increases; generally, when the pressure is greater than 1.6 Mpa, cast steel is used for pressure-bearing components! IV. Carbon structural steel: It is usually divided into ordinary carbon structural steel and high-quality carbon structural steel. V. Alloy steels: The most representative alloy steel is 40Cr, which is commonly used as material for high-strength pump shafts. VI. Non-metallic materials: Non-metallic materials used in pumps are primarily for sealing purposes, such as polytetrafluoroethylene, fluororubber, nitrile rubber, etc. Among them, polytetrafluoroethylene is used for gaskets in chemical pumps and as a static seal in mechanical seals due to its excellent corrosion resistance and high-temperature tolerance; it is suitable for almost all chemical media at temperatures up to 250°C. Its disadvantages are high hardness and difficulty in installation. Fluororubber is also a good material for withstanding high temperatures and corrosion; its maximum temperature tolerance is around 160°C. Unless the user has specific requirements, chemical pumps use seals made of this material ； Nitrile rubber is primarily used for static sealing in oil-resistant or clean water environments. Classification of cast iron materials for pump bodies: 1. Gray cast iron for pump bodies. It has a high carbon content (2.7%–4.0%), with carbon existing primarily in the form of flake graphite; its fracture surface is gray, hence it is also known as gray cast iron. It has a low melting point (1145–1250°C), experiences little shrinkage during solidification, its compressive strength and hardness are similar to those of carbon steel, and it offers good shock absorption. Used to manufacture structural components such as machine tool beds, cylinders, and enclosures. 2. White cast iron. The carbon and silicon contents are low; carbon exists mainly in the form of cementite, and the fracture surface is silver-white in color. It contracts significantly during solidification, making it prone to shrinkage cavities and cracks. It has high hardness and high brittleness, and cannot withstand impact loads. It is often used as blanks for malleable cast iron and to manufacture wear-resistant components. 3. Malleable cast iron. It is obtained by annealing white cast iron, with graphite distributed in agglomerate form; it is also referred to as ductile iron. It has uniform mechanical properties, is wear-resistant, and possesses good plasticity and toughness. Used to manufacture parts with complex shapes that can withstand high dynamic loads. 4. Ductile iron. It is obtained by spheroidizing gray cast iron molten metal, resulting in spherical graphite particles; it is commonly referred to as spheroidal cast iron. It has higher strength, as well as better toughness and plasticity compared to ordinary gray cast iron. Used in the manufacture of internal combustion engines, automotive parts, and agricultural machinery, etc. 5. Nodular cast iron. It is obtained by creep treatment of gray cast iron melt, with the precipitated graphite appearing worm-like. Its mechanical properties are similar to those of ductile iron, while its castability lies between that of gray cast iron and ductile iron. Parts used in manufacturing cars. 6. Alloy cast iron. It is obtained by adding appropriate amounts of alloying elements (such as silicon, manganese, phosphorus, nickel, chromium, molybdenum, copper, aluminum, boron, vanadium, tin, etc.) to ordinary cast iron. Alloying elements alter the matrix structure of cast iron, thereby endowing it with corresponding properties such as heat resistance, wear resistance, corrosion resistance, low-temperature resistance, or magnetism-free characteristics. Used to manufacture components for mining machinery, chemical engineering equipment, and instruments.