The invention belongs to the technical field of automobile manufacturing, and particularly relates to a preparation method of an automobile
fastener wire. The preparation method provided by the invention comprises the steps of providing a low-
carbon alloy steel wire, wherein the carbon content of the low-
carbon alloy steel wire is 0.19 wt% to 0.21 wt%, and the
boron content of the low-carbon alloysteel wire is 0.0005 wt% to 0.0030 wt%; sequentially carrying out acid
pickling and phosphorization on the low-
carbon alloy steel wire, and then carrying out first drawing treatment to obtain a firstdrawing product; carrying out spheroidizing annealing treatment on the first drawing product, and obtaining a spheroidizing annealing product, wherein the spheroidizing annealing treatment comprisesthe steps of heating the first drawing product to 710-730 DEG C in a protective
atmosphere, and keeping the temperature for 5-8 hours; cooling to 540-560 DEG C at a speed of 20 DEG C / h, continuously cooling to 390-410 DEG C at a speed of 80 DEG C / h, and naturally cooling to normal temperature, wherein the protective
atmosphere is
methanol pyrolysis gas when the temperature is 550 DEG C or above, and the protective
atmosphere is
nitrogen when the temperature in the furnace is lower than 550 DEG C; and sequentially carrying out acid
pickling and phosphorization on the spheroidizing annealing product, and carrying out second drawing treatment, wherein
sodium nitrite is adopted as an
accelerant for phosphorization.