55SiCr is the high-grade steel used for automobile suspension springs. The suspension springs bear the reciprocating compression motion in the process of automobile driving, and play the role of buffer and shock absorption, which has high requirements on the performance of steel.Decarburization is one of the main problems in the hot processing of spring steel. Decarburization of spring steel surface will seriously damage the fatigue performance of spring, especially when the total decarburization of ferrite occurs on spring steel surface, the fatigue limit of spring can be reduced by 50%.At present, studies on decarburization of spring steel surface mainly focus on two influencing factors of heating temperature and heating time, while studies on the effect of heating furnace atmosphere on decarburization of spring steel are few.Based on the actual production conditions of the on-site heating furnace, researchers of Beijing university of science and technology studied the influence of heating temperature, holding time and atmosphere in the heating furnace on the surface decarbonization of 55SiCr of spring steespringsl in the laboratory, and conducted thermodynamic analysis of decarbonization reaction.Results show that the area of 950 ℃ ~ 1250 ℃ temperature, thickness of spring steel decarburized layer completely to increase after the first decreases, and 1200 ℃ when completely reach maximum thickness of the decarburization layer, due to oxidation decarburization rate faster than 1250 ℃, the decarburization layer completely disappear.The fully decarburized layer thickness of spring steel increased significantly with the extension of heating time, the increase of CO2 content in atmosphere, O2 content and H2O(g) content.When the temperature is 950 ℃, O2 content in the atmosphere is 1%, the heating time is 35 minutes, under the condition of the formation of the decarburization layer can be avoided completely.