Do high temperature resistant bolts and nuts have excellent creep and oxidation resistance?
Publish Time: 2025-10-04
In modern industrial systems, many critical equipment, such as gas turbines, steam boilers, oil refinery crackers, aerospace engines, and nuclear power systems, operates under extremely high-temperature environments for extended periods of time. In these harsh, high-temperature, high-pressure environments, the reliability of mechanical connections is directly related to the safe operation and lifespan of the equipment. As core components of the connection structure, bolts and nuts must not only withstand enormous preloads and working loads, but also maintain stable performance under sustained high temperatures. Ordinary carbon steel or standard stainless steel fasteners often struggle in these situations, prone to failure due to material softening, stress relaxation, or chemical degradation. Therefore, whether high temperature resistant bolts and nuts have excellent creep resistance and oxidation resistance becomes the decisive criterion for measuring whether they can work reliably for a long time in extreme environments.Creep resistance is one of the most critical properties of high-temperature resistant fasteners. Creep refers to the slow and continuous plastic deformation of a material under the combined effects of high temperature and sustained stress. At room temperature, metal materials return to their original shape after being stressed within their elastic range. However, at high temperatures, atomic activity intensifies, leading to active grain boundary sliding. Even if the stress does not reach the yield strength, the material will gradually "flow" and deform over time. For bolts, this slight elongation can cause the preload to decrease, leading to loosening of the joint, seal failure, and even leakage, vibration, or structural disintegration. High-quality high-temperature resistant bolts and nuts are made from special alloys, such as nickel-based superalloys and austenitic heat-resistant stainless steel. These materials maintain high yield strength and structural stability at high temperatures, effectively suppressing creep. Furthermore, through a precise upsetting process, metal fibers are continuously distributed along the bolt's axis, further enhancing the overall structure's resistance to deformation and ensuring reliable clamping force even under long-term high-temperature loads.High temperature resistant bolts and nuts' oxidation resistance is another indispensable performance. At high temperatures, metal surfaces react easily with oxygen, forming an oxide layer. Ordinary steel rapidly oxidizes at temperatures of several hundred degrees Celsius, forming a loose, porous oxide scale. This not only affects appearance but also reduces the effective cross-section, accelerating material degradation. More seriously, the oxidation process may be accompanied by decarburization, grain boundary oxidation, or selective oxidation, which damages the material's internal structure and reduces mechanical properties. The alloy materials used in high-quality high-temperature resistant bolts and nuts contain elements such as chromium, aluminum, and silicon, which can form a dense, stable and self-healing oxide film on the surface, such as chromium oxide or aluminum oxide. This protective film effectively blocks oxygen diffusion and slows the oxidation rate, ensuring that the fastener maintains surface integrity and structural strength even in high-temperature flue gases, steam, or circulating air. Some products also undergo surface treatments, such as aluminizing, nickel plating, or ceramic coatings, to further enhance oxidation resistance and extend service life.In practical applications, the combination of high temperature resistant bolts and nuts' creep resistance and oxidation resistance ensures the long-term reliability of fasteners in extreme environments. For example, in the hot end of a gas turbine, bolts must withstand immense centrifugal forces and vibration at temperatures near the material's melting point. Without excellent creep and oxidation resistance, they are prone to breakage or loosening, resulting in catastrophic consequences. Furthermore, in high-temperature pipe flange connections in petrochemical plants, bolts must operate continuously for years at temperatures exceeding hundreds of degrees Celsius. Their oxidation resistance determines whether they will corrode and become impossible to remove during maintenance.In summary, the true value of high-temperature resistant bolts and nuts lies not only in their ability to withstand high temperatures but also in their durability and reliability in such conditions. Excellent creep resistance ensures that their mechanical properties remain stable over time, while oxidation resistance safeguards their structural integrity from environmental degradation. Together, these two qualities form the lifeblood of high-temperature fasteners, making them the most reliable connection solutions for extreme operating conditions. Choosing upsetting forgings with superior creep and oxidation resistance provides an invisible yet robust safety barrier for critical equipment.
