Spring flat steel raw material decarburized layer control method suitable for high-stress plate spring

A spring flat steel raw material decarburized layer control method suitable for a high-stress plate spring comprises the steps of steel billet treatment and heating, and the steel billet treatment is that shot blasting point coping treatment is conducted on a steel billet; the steel billet is fed into a heating furnace and is heated in a three-section heating mode, the temperature of a preheating section is lower than 650 DEG C, the temperature of a heating section is 1010 +/-50 DEG C, the temperature of a soaking section is 1050 +/-50 DEG C, the total heating time is 90-120 minutes, it is guaranteed that the temperature of the core of the steel billet is larger than or equal to 800 DEG C, and in the heating process, the ratio of air to fuel gas in the heating section is smaller than or equal to 2.7; the air flow/gas flow of the soaking section is smaller than or equal to 2.2, the content of residual oxygen in the heating furnace is 3.0-7.0%, and the pressure in the heating furnace is kept at 30-35 Pa. The de