The Material Of Couplings

What material is commonly used for couplings?

At present, the main materials used for manufacturing couplings include cast iron, cast steel, 45 # steel, 40Cr, stainless steel, aluminum alloy, etc.

Among them, the most commonly used material is 45 # steel. Plum shaped couplings, star shaped couplings, tire type couplings, etc. are all made of this material. Better materials include 40Cr and 40CrMo. Diaphragm couplings and expansion sleeves are generally made of this material. In addition, some couplings have lower requirements for use, so the materials used are slightly inferior, such as flange couplings and clamp type couplings, which mainly use cast iron or cast steel.

Characteristics of various materials:

1. Cast iron and cast steel: The casting and forming of steel includes cast iron and cast steel parts, both of which are produced through general smelting technology or simple equipment. Although both are iron carbon alloys, due to the different percentages of chemical elements such as carbon, silicon, manganese, phosphorus, and sulfur, they have different metallographic structures after crystallization, showing many differences in mechanical and process properties. In the casting state, the elongation, cross-sectional shrinkage, and impact toughness of cast steel are higher than those of cast iron, while the compressive strength and shock absorption performance of cast iron are better than those of cast steel; During the bending test, cast iron exhibits brittle fracture, while cast steel exhibits bending deformation.

Cast iron: It is relatively wear-resistant and often produces pores inside the material during the casting process, resulting in lower overall strength, toughness, and plasticity of the material, but at a lower price.

Cast steel: Cast steel parts have similar properties to cast iron, but have better strength than cast iron and can be welded, with a slightly higher price than cast iron.

2. 45 # steel: 45 # steel is a medium carbon structural steel with good cold and hot processing performance, good mechanical properties, moderate price, and wide source, so it is widely used. Its disadvantage is that it has low hardenability, and workpieces with large cross-sectional dimensions and high requirements are not suitable for use.

3. 40Cr: The carbon content of this material is 0.37% to 0.44%, slightly lower than 45 # steel (0.42% to 0.50%). Compared with 45 # steel, the difference lies in the fact that after heat treatment, the main role of Cr in heat treatment is to improve the hardenability of the steel. Due to the improved hardenability, the mechanical properties such as strength, hardness, and impact toughness of 40Cr after quenching (or tempering) treatment are significantly higher than those of 45 # steel, so the price is also higher. 40Cr material is mainly used in couplings with larger outer diameters.