The invention relates to an automotive
brake disc and a
surface modification method thereof. The
surface modification method of the automotive
brake disc comprises the following steps of (1)
stress relief annealing, specifically,
stress relief treatment is conducted on the
brake disc; (2) vacuumizing for the first time, specifically, the brake disc is transferred into an oxidizing furnace, vacuumizing is conducted for the furnace pressure, and then the furnace pressure is balanced through
nitrogen; (3) pre-oxidation, specifically, pre-oxidation is conducted on the brake disc; (4) tufftriding, specifically, the brake disc is transferred into a
nitriding furnace, and nitrocarburizing is conducted; (5) rapid cooling for the first time, specifically, the brake disc is taken out of the
nitriding furnace to be cooled rapidly; (6) vacuumizing for the second time, specifically, the brake disc is placed in the oxidizing furnace, vacuumizing is conducted for the furnace pressure, and then the furnace pressure is balanced through
nitrogen; (7) post-oxidation, specifically, post-oxidation is conducted on the brake disc; (8) rapid cooling for the second time, specifically, the post-oxidized brake disc is cooled rapidly; and (9) vacuumizing for the third time, specifically, vacuumizing is conducted for the furnace pressure, then the furnace pressure is balanced through
nitrogen, and the treated brake disc is taken out of the furnace. By the adoption of the
surface modification method, the
hardness, abrasion resistance, fatigue-resisting strength and high temperature-resisting engagement performance of the brake disc can be improved.