English Views: 39 Author: Site Editor Publish Time: 2025-08-19 Origin: Site
I. Comparison of Common Materials for Disc Springs
According to the GB/T1222 standard for spring steel, the chemical compositions (mass fraction) are as follows:
Serial number | Grade | Chemical composition (mass fraction)/% | ||||||||||
C | Si | Mn | Cr | V | W | B | N i | C u | P | S | ||
not greater than | ||||||||||||
1 | 50CrV A | 0.46 -0.54 | 0.17 -0.37 | 0. 5 -0. 8 | 0.8 -1.1 | 0.1-0.2 | 0.35 | 0.25 | 0.025 | 0.025 | ||
2 | 60Si2 MnA | 0.56 -0.64 | 1.6 -2. 0 | 0. 7 -1. 0 | ≤0. 35 | 0.35 | 0.25 | 0.025 | 0.025 | |||
II. Mechanism of Alloying Elements in Spring Steel
The role of alloying elements in spring steel is complex. Below is an analysis of the main alloying elements in low-alloy spring steel:
1. Carbon (C)
Carbon is the fundamental strengthening element in spring steel. It primarily contributes to solid solution strengthening and dispersion strengthening (forming finely dispersed carbides with other alloying elements). It is an indispensable element in spring steel.
2. Silicon (Si)
Silicon is not a carbide-forming element. It has a strong solid solution strengthening effect and primarily enhances solid solution strengthening in steel. By inhibiting the nucleation and growth of cementite during tempering, silicon alters the morphology and distribution of cementite, thereby improving the steel's resistance to relaxation. Within an appropriate range, higher silicon content increases resistance to elastic degradation. However, silicon tends to promote decarburization in steel. When the silicon and carbon content exceeds a certain ratio, graphitization may occur, leading to black fracture surfaces.
3. Manganese (Mn)
Manganese improves the hardenability of steel and provides some solid solution strengthening. However, excessive manganese content increases thermal sensitization and temper brittleness, as well as the tendency for cracking during quenching.
4. Chromium (Cr)
Chromium is a crucial alloying element in spring steel. It significantly enhances hardenability, oxidation resistance, and corrosion resistance, while also improving tempering stability and the balance between strength and toughness. Adding 0.50% chromium to steel can increase yield strength by 16% and reduce decarburization depth by 50%. Chromium also effectively prevents graphitization during spheroidizing annealing of Si-Mn spring steel.
5. Nickel (Ni)
Nickel is expensive and is generally not intentionally added during the smelting of spring steel. It mostly exists as a residual element. Only a few high-quality spring steels contain 0.20%–0.50% nickel to improve toughness.
6. Vanadium (V)
Vanadium is a strong carbide-forming element. It forms fine, highly dispersed, and very hard VC particles in steel, which refine the grain structure and improve plasticity, toughness, and the yield-to-tensile ratio.
III. Comparative Destructive Fatigue Testing
A comparative destructive fatigue test was conducted on disc springs made from these two materials. The results showed that disc springs made from 50CrVA exhibited a longer service life, with less creep and relaxation.
