Low-Temperature Elasticity Retention and Usage Limitations of Spring Clips
- What are the differences in the elastic changes of elastic clips of different materials at low temperatures?
The elastic retention rate of 60Si2CrA elastic clips is about 90% at -20℃, and can still maintain more than 75% at -40℃, with relatively stable low-temperature performance; the elastic retention rate of 55SiMnVB elastic clips drops to 80% at -20℃, and only 60% at -40℃, with obvious elastic decline; 65Mn elastic clips have the worst low-temperature performance, with elastic retention rate lower than 70% at -10℃ and less than 50% at -30℃, prone to brittle deformation.
- What process factors are related to the low-temperature elastic retention of elastic clips?
Heat treatment process has a significant impact. Elastic clips with low-temperature tempering (380-420℃) have 10%-15% higher low-temperature elastic retention than those with high-temperature tempering (450-500℃). Surface treatment also plays a role. Elastic clips with carburizing treatment have increased surface hardness, are not easy to produce plastic deformation at low temperatures, and have better elastic retention. The degree of grain refinement during rolling is different. The finer the grains of the elastic clips, the better the low-temperature toughness and elastic retention.
- What are the requirements for the elastic retention rate of elastic clips in cold regions?
In regions below -30℃ such as Northeast China and Inner Mongolia, the elastic retention rate of elastic clips at the minimum temperature is required to be no less than 70%, and the elastic loss after 100 freeze-thaw cycles shall not exceed 15%. In North China (-10 to -20℃), the elastic retention rate must be ≥80%, and the elastic loss after freeze-thaw cycles shall be controlled within 10%. In regions with large temperature differences between day and night such as the Qinghai-Tibet Plateau, in addition to low-temperature elasticity requirements, the elastic stability during sudden temperature changes must also be met.
- How to test the low-temperature elastic retention of elastic clips?
Place the elastic clip in a low-temperature test chamber, keep it at the set temperature (such as -40℃, -30℃) for 4 hours, then measure its rebound value under the standard deformation, compare it with the rebound value at room temperature, and calculate the elastic retention rate. At the same time, conduct freeze-thaw cycle tests, repeatedly cycle the elastic clip between -40℃ and 20℃ for 50-100 times, test the elastic change after each cycle, and evaluate its low-temperature fatigue resistance.
- What are the usage restrictions of elastic clips in low-temperature environments?
65Mn elastic clips are prohibited from being used in areas below -20℃ to avoid sudden drop in clamping force due to insufficient elasticity. 55SiMnVB elastic clips in areas below -30℃ need to shorten the inspection cycle from the conventional once every 3 months to once a month. Even 60Si2CrA elastic clips need to be temporarily speed-limited when the temperature is extremely low below -40℃, with the train speed not exceeding 80km/h to reduce the damage of impact load to the elastic clips.