Steel sheet plated with Al—Fe alloy for hot press forming having excellent corrosion resistance and heat resistance, hot press formed part, and manufacturing method therefor

A method of manufacturing a steel sheet plated with an Al—Fe alloy for hot forming, the method comprising:

• aluminum-plating and coiling a base steel sheet to obtain an aluminum-plated steel sheet, wherein an amount of the aluminum-plating is 30 to 200 g/m2 based on one surface of the base steel sheet, and tension in the coiling is 0.5 to 5 kg/mm2;
• after the aluminum-plating, performing cooling to 250° C. at a rate of 20° C./see or less;
• annealing the aluminum-plated steel sheet to obtain the steel sheet plated with the Al—Fe alloy;
• and
• cooling the steel sheet plated with the Al—Fe alloy,
• wherein,
• the annealing is carried out for 30 minutes to 50 hours within a heating temperature range of 550 to 750° C. in a batch annealing furnace,
• when heating from room temperature to the heating temperature during the annealing, an average temperature increase rate is 10 to 100° C./h, and an average temperature increase rate in a 400 to 500° C. section is 1 to 15° C./h,
• a difference between an atmospheric temperature in the batch annealing furnace and a steel sheet temperature is 5 to 80° C.,
• the Al—Fe alloy comprises:
• an alloyed layer (I) on the base steel sheet and including Al:
• 5 to 30% by weight;
• an alloyed layer (II) on the alloyed layer (I) and including Al:
• 30 to 60% by weight;
• and
• an alloyed layer (III) on the alloyed layer (II) and including Al:
• 20 to 50% by weight,
• FeAl(Si) alloy phases including Al:
• 20 to 50% and Si:
• 5 to 20%, by weight, are dispersed and distributed in the alloyed layer (II), and
• a number density of the FeAl (Si) alloy phases having a circle-equivalent diameter of 5 μm or less is 103 pieces/mm2 or more.