SiMn spring steel without fully decarburized layer and manufacturing method of SiMn spring steel

The invention provides SiMn spring steel without a fully decarburized layer and a manufacturing method of the SiMn spring steel. The manufacturing method comprises the steps of blank charging, heating treatment, dephosphorization treatment and rolling treatment. The heating treatment comprises a preheating section, a first heating section, a second heating section and a soaking section; the temperature of the preheating section is 600-800 DEG C; the temperature of the first heating section is 1000-1100 DEG C; the temperature of the second heating section is 1050-1200 DEG C; and the temperature of the soaking section is 1150-1250 DEG C. According to the SiMn spring steel manufactured through the manufacturing method, the thickness of a fully decarburized layer is 0, the total thickness of the decarburized layer meets the GB standard requirement, and the yield is larger than or equal to 95%. 本发明提供了一种无全脱碳层的SiMn弹簧钢及其制造方法，该制造方法包括坯料装炉、加热处理、除磷处理和轧制处理；所述加热处理包括预热段、加热一段、加热二段和均热段；所述预热段温度为600～800℃；所述加热一段温度为1000～1100℃；所述加