Treatment process for blackening surface of steel part

The invention relates to the technical field of metal product surface treatment, in particular to a steel part surface blackening treatment process which comprises the steps that S1, a workpiece is pretreated; s2, vacuumizing in a furnace; s3, carbonitriding is carried out; s4, blackening treatment is carried out; according to the treatment process, molecules on the surface of the workpiece have activity through nitriding treatment, then oxidation is conducted through the acidic aqueous solution, the surface of the workpiece is blackened, the color is dark, and the requirements of special industries can be met; ferroferric oxide is formed in the oxidation process, a nitriding layer is formed in the nitriding process, the surface hardness of the workpiece can be greatly improved through the two structures, and the workpiece can have abrasion resistance; by means of the method, the workpiece can have good corrosion resistance, the effect that the workpiece is not corroded within 760 hours in a neutral salt spra