Carburizing process of countersunk self tapping screws

In the carburizing process of countersunk self tapping screws, the deep carburizing process is different. For workpieces with a carburized layer depth greater than 1.0 mm, such as automobile gears, the carburized layer depth and the carbon concentration distribution of the layer, even the layer The depth of the over-eutectoid layer and the eutectoid layer may have certain requirements. In order to ensure a high carburization rate, such parts are often diffused using an atmosphere having a carbon potential of 0.7% C-0.8% C after high carbon potential carburization. In order to reduce the distortion caused by direct quenching after carburizing and reduce the martensite and retained austenite grade, the process of furnace cooling to 820-860 ° C isothermal and then quenching is required after the end of the diffusion phase to ensure that the layer and the core are Qualified hardness and good microstructure. The requirements for carrier gas and rich gas in this carburizing process are different from those of self-tapping screws.