Select spring material based on the temperature difference
2023-04-26
Spring materials operating under high-temperature conditions require high strength, good thermal stability, relaxation or creep resistance, oxidation resistance, and resistance to certain media corrosion.
As the operating temperature of the spring increases, the elastic modulus of the spring material decreases, leading to a decrease in stiffness and load-carrying capacity. Therefore, for springs operating under high-temperature conditions, it is essential to understand the rate (value) of change in the elastic modulus and calculate the impact of the reduced spring load-carrying capacity on the performance. According to regulations, when the operating temperature of a helical spring is above 60℃, the shear modulus should be corrected. The formula is: Gt=KtG where G is the elastic modulus at room temperature; Gt is the shear modulus at operating temperature t; Kt is the temperature correction factor, selected according to Table 2-98.
Spring materials used at lower temperatures should possess good low-temperature toughness. Carbon steel spring wire, piano wire, and austenitic stainless steel spring wires such as 1Cr18Ni9, copper alloys, and nickel alloys exhibit good low-temperature toughness and strength. At lower temperatures, the brittleness of the material is highly sensitive to surface defects; therefore, the surface quality of the material should be strictly controlled. At lower temperatures, the corrosion level of the material by environmental media is much lower than at room temperature, while cadmium plating and zinc plating can easily cause cold brittleness. At lower temperatures, the elastic modulus and coefficient of thermal expansion of the material do not change significantly and can be ignored in design.
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