English Views: 68 Author: Site Editor Publish Time: 2026-04-15 Origin: Site
Analysis of Relaxation Failure Mechanism and Anti-relaxation Design Selection Guide for High-Temperature Disc Spring
In high-temperature operating conditions of industrial sectors such as energy, petrochemicals, and metallurgy, disc springs serve as critical elastic components, and their long-term reliability directly impacts equipment operational safety. According to industry data, the global high-temperature spring market size has exceeded 8 billion yuan by 2025, with China accounting for over 35% of the market share. However, equipment failures caused by stress relaxation and creep under high-temperature environments account for more than 23%. This paper systematically analyzes the failure mechanisms of stress relaxation and creep in disc springs under high-temperature conditions, providing scientific material selection, structural design, and application maintenance solutions to help industrial enterprises enhance equipment stability under extreme operating conditions.
Metal materials undergo grain boundary diffusion and dislocation climb under high-temperature conditions, resulting in gradual attenuation of initial stress over time. When operating temperatures exceed 0.5 times the material's recrystallization temperature (e.g., Inconel 718 alloy at over 650°C), intensified atomic thermal motion transforms elastic deformation into plastic deformation, manifesting as sustained reduction in disc spring preload. A case study from a petrochemical plant's reactor sealing system revealed that conventional 50CrVA disc springs experienced 32% preload degradation after six months of operation at 450°C, significantly increasing the risk of medium leakage.
Creep is a slow plastic deformation process resulting from the combined effects of high temperature and stress, consisting of three stages: initial creep, steady-state creep, and accelerated creep. Studies indicate that when temperature rises from 300°C to 500°C, the steady-state creep rate of Inconel 718 disc springs can increase by 2-3 orders of magnitude. Typical failure manifestations include permanent reduction in free height (requiring replacement when exceeding 5%), nonlinear shifts in load-deformation curves, and in severe cases, insufficient sealing pressure or mechanical jamming. Failure analysis of wind turbine pitch systems reveals that under alternating loads at 550°C, the average lifespan of unoptimized disc spring assemblies is only 67% of their designed value.
Based on the integration of materials science and engineering practices, high-temperature relaxation resistance design requires systematic implementation across four dimensions: material selection, process optimization, structural design, and application maintenance.
1. Gradient Material Selection Strategy: Select appropriate materials based on operating temperature ranges. For temperatures between 300-400°C, 50CrVA alloy (with special tempering treatment) is recommended. For 400-600°C, Inconel 718 alloy is preferred, while Inconel X750 can be used for extreme conditions exceeding 600°C. Materials must meet the high-temperature elastic performance requirements specified in GB/T 1972-2005 standards, ensuring room temperature hardness of HRC42-48 and maintaining a high-temperature elastic modulus retention rate of ≥85%.
2. Multi-stage heat treatment process: A composite process combining "solid solution treatment + aging strengthening + low-temperature tempering" is employed. For Inconel alloy series, the recommended treatment sequence includes 980°C/1h solid solution treatment, 720°C/8h aging, followed by 300°C/2h low-temperature tempering to eliminate residual stresses. Process control must ensure furnace temperature uniformity within ±5°C and cooling rate ≥15°C/min to achieve stable γ' strengthening phase.
3. Collaborative temperature field design: Establishing operating condition temperature distribution maps to prevent localized hot spots from exceeding material allowable temperatures. Finite element simulations (e.g., ANSYS Mechanical) are employed to model the impact of temperature gradients on material relaxation, with real-time temperature monitoring sensors installed at critical locations. Practical applications in a nuclear power project demonstrated that thermal shielding design can reduce the operating temperature of disc springs by 80-120°C, significantly extending their service life.
4. Dynamic Compensation System for Pre-tensioning Force: The initial preload should incorporate a 15-20% slack compensation allowance, with torque-angle method employed for precise installation load control. Critical equipment requires integrated load monitoring devices that trigger alerts when pre-tension force decay exceeds 10%. For stacked assembly configurations, adhere to the principle of "increased stiffness through interlocking and extended stroke through merging," while applying molybdenum disulfide grease between components to minimize friction loss.
Industrial practice demonstrates that scientifically designed selection methods can extend the service life of high-temperature disc springs by 2-3 times. It is recommended that enterprises initiate operational condition assessments during equipment design phases, with professional technical teams conducting material screening, structural optimization, and performance validation. For critical operating conditions exceeding 400°C, companies should engage technical service providers with expertise in high-temperature material applications to provide end-to-end lifecycle support, including failure analysis, remaining life assessment, and upgrade solution development.
1. Sealing System for Petrochemical Reactor: In a 300,000-ton/year ethylene plant, Inconel 718 disc spring assemblies were adopted to replace conventional helical springs, achieving leak-free continuous operation for 18 months under 480°C and 12MPa conditions—representing a 120% lifespan improvement over the original design. Key enhancements include: a "parallel + combined" structural configuration (3 pairs of 2 units), a pre-tightening force design value of 18kN, a 25% compensation allowance, and surface treatment with an Aluminizing coating.
2. Metalurgical High-Temperature Furnace Door Clamping Mechanism: During a heating furnace retrofit project at a steel enterprise, the original 50CrVA disc spring exhibited 12% free height reduction after just three months at 600°C. By replacing it with Inconel X750 material and implementing a gradient pre-tightening design (1.2mm cold-state pre-compression and 0.8mm hot-state compensation), the maintenance cycle was extended to 18 months, resulting in annual downtime cost savings of approximately 450,000 yuan.
3. Wind Turbine Pitch System Buffer Assembly: To address high-temperature failure issues in offshore wind turbine gearboxes, a project implemented 17-7PH stainless steel disc springs (subjected to H900 aging treatment) paired with titanium alloy isolation washers. This configuration achieved a fatigue life of 10^6 cycles during temperature cycling between-40°C and 120°C, representing an 85% improvement over the original design. Key technical features include shot peening reinforcement (100% coverage rate, 0.2 mmA strength) and controlled surface roughness with Ra ≤ 0.8 μm.
1. Condition parameter collection: Specify operating temperature (instantaneous/continuous), load type (static/dynamic), cycle count, environmental medium (corrosive/oxidizing), and installation space constraints;
2. Material compatibility verification: In accordance with GB/T 1972 standards and ISO 7500-1 static load test data, select a material scheme with a safety factor ≥1.5.
3. Structural simulation optimization: Through FEM analysis, verify the stress distribution of the stacked assembly to ensure that the maximum stress does not exceed 60% of the material's high-temperature yield strength.
4. Sample performance testing: Conduct a 1000-hour high-temperature relaxation test (temperature fluctuation ±2°C), requiring residual deformation ≤3% and load decay rate ≤8%.
1. Installation process control: Apply preload using hydraulic tensioners or torque wrenches, and implement cross-symmetric tightening for multi-bolt systems to ensure load uniformity error ≤5%.
2. Operation monitoring protocol: It is recommended to install strain gauges or load sensors on critical equipment to monitor preload force changes in real time, with three-tier warning thresholds set (8%/15%/25% attenuation).
3. Regular maintenance cycle: Under normal operating conditions, free height should be inspected every 6 months; in high-temperature environments (>400°C) or corrosive environments, inspections should be conducted every 3 months. Immediate replacement is required if permanent deformation exceeds 5%.
4. Storage protection requirements: Uninstalled disc springs shall be stored in a dry and well-ventilated environment, avoiding contact with corrosive media. The stacking height shall not exceed 100 mm to prevent plastic deformation.
With the development of industrial equipment towards high-parameterization, high-temperature disc spring technology has shown three major innovation directions: In terms of materials, new cobalt-based alloys (such as Haynes 282) can increase the operating temperature to 750°C; in terms of structure, gradient-thickness disc springs achieve uniform stress distribution through variable cross-section design; in terms of manufacturing, laser additive technology enables integrated forming of complex topological structures. According to the "China High-Temperature Disc Spring Industry Research Report," the domestic market for special disc springs with high-temperature resistance above 600°C is expected to achieve a compound annual growth rate of 12.3% from 2025 to 2027, driving continuous improvement in the reliability of high-end equipment.
Conclusion: The anti-relaxation design of high-temperature disc springs constitutes a systematic engineering endeavor requiring deep integration of materials science, structural mechanics, and practical engineering applications. Enterprises should adopt a full lifecycle management approach, implementing standardized control measures from selection design, installation and commissioning to operation and maintenance. Through professional technical support and scientific management strategies, we can maximize the critical performance of high-temperature disc springs under extreme operating conditions, thereby providing robust safeguards for the safe and stable operation of industrial equipment.
