Selection of bolt and nut materials

When selecting the material for bolts and nuts, various factors are typically taken into consideration, such as the operating environment, temperature, pressure, and corrosion resistance requirements. The HG20613 and 20634 standards offer different material options to meet various application conditions and performance requirements. 1. **Operating temperature and pressure**: Different materials have varying strength and temperature resistance properties. 35CrMo (often used in combination with 30CrMo) is a high-temperature and high-pressure resistant alloy material, suitable for medium temperature and pressure conditions. A320 L7 and A194 7, on the other hand, are alloy steels suitable for low-temperature environments, capable of maintaining good mechanical properties and toughness in a temperature range of -101°C to 650°C. 2. **Corrosion resistance**: In chemical handling or marine applications, higher requirements are placed on the corrosion resistance of materials. For example, certain special materials (such as stainless steel or nickel-based alloys) may be chosen for extreme corrosive environments. 3. **Cost and availability**: Different materials also have varying costs. While ensuring safety and performance, it is often necessary to strike a balance between cost-effectiveness and performance. 4. **Specifications and standards**: Project specifications may require the use of materials that meet certain standards, which can be influenced by region, **standards, or industry-specific standards. In summary, even under the same pressure and temperature conditions, different bolt and nut materials may be chosen due to factors such as cost, availability, corrosion resistance requirements, and regulatory specifications. Therefore, when making a choice, it is necessary to carefully evaluate the usage environment and performance requirements, and refer to relevant standards to make an appropriate selection. .